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+Independent Submission                                        P. Calhoun
+Request for Comments: 5412                                       R. Suri
+Category: Historic                                         N. Cam-Winget
+ISSN: 2070-1721                                      Cisco Systems, Inc.
+                                                             M. Williams
+                                                   GWhiz Arts & Sciences
+                                                                S. Hares
+                                                               B. O'Hara
+                                                                 S.Kelly
+                                                           February 2010
+
+
+                   Lightweight Access Point Protocol
+
+Abstract
+
+   In recent years, there has been a shift in wireless LAN (WLAN)
+   product architectures from autonomous access points to centralized
+   control of lightweight access points.  The general goal has been to
+   move most of the traditional wireless functionality such as access
+   control (user authentication and authorization), mobility, and radio
+   management out of the access point into a centralized controller.
+
+   The IETF's CAPWAP (Control and Provisioning of Wireless Access
+   Points) WG has identified that a standards-based protocol is
+   necessary between a wireless Access Controller and Wireless
+   Termination Points (the latter are also commonly referred to as
+   Lightweight Access Points).  This specification defines the
+   Lightweight Access Point Protocol (LWAPP), which addresses the
+   CAPWAP's (Control and Provisioning of Wireless Access Points)
+   protocol requirements.  Although the LWAPP protocol is designed to be
+   flexible enough to be used for a variety of wireless technologies,
+   this specific document describes the base protocol and an extension
+   that allows it to be used with the IEEE's 802.11 wireless LAN
+   protocol.
+
+Status of This Memo
+
+   This document is not an Internet Standards Track specification; it is
+   published for the historical record.
+
+   This document defines a Historic Document for the Internet community.
+   This is a contribution to the RFC Series, independently of any other
+   RFC stream.  The RFC Editor has chosen to publish this document at
+   its discretion and makes no statement about its value for
+   implementation or deployment.  Documents approved for publication by
+   the RFC Editor are not a candidate for any level of Internet
+   Standard; see Section 2 of RFC 5741.
+
+
+
+Calhoun, et al.                 Historic                        [Page 1]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Information about the current status of this document, any errata,
+   and how to provide feedback on it may be obtained at
+   http://www.rfc-editor.org/info/rfc5412.
+
+IESG Note
+
+   This RFC documents the LWAPP protocol as it was when submitted to the
+   IETF as a basis for further work in the CAPWAP Working Group, and
+   therefore it may resemble the CAPWAP protocol specification in RFC
+   5415 as well as other IETF work.  This RFC is being published solely
+   for the historical record.  The protocol described in this RFC has
+   not been thoroughly reviewed and may contain errors and omissions.
+
+   RFC 5415 documents the standards track solution for the CAPWAP
+   Working Group and obsoletes any and all mechanisms defined in this
+   RFC.  This RFC is not a candidate for any level of Internet Standard
+   and should not be used as a basis for any sort of Internet
+   deployment.
+
+Copyright Notice
+
+   Copyright (c) 2010 IETF Trust and the persons identified as the
+   document authors.  All rights reserved.
+
+   This document is subject to BCP 78 and the IETF Trust's Legal
+   Provisions Relating to IETF Documents
+   (http://trustee.ietf.org/license-info) in effect on the date of
+   publication of this document.  Please review these documents
+   carefully, as they describe your rights and restrictions with respect
+   to this document.
+
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+Calhoun, et al.                 Historic                        [Page 2]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+Table of Contents
+
+   1. Introduction ....................................................8
+      1.1. Conventions Used in This Document ..........................9
+   2. Protocol Overview ..............................................10
+      2.1. Wireless Binding Definition ...............................11
+      2.2. LWAPP State Machine Definition ............................12
+   3. LWAPP Transport Layers .........................................20
+      3.1. LWAPP Transport Header ....................................21
+           3.1.1. VER Field ..........................................21
+           3.1.2. RID Field ..........................................21
+           3.1.3. C Bit ..............................................21
+           3.1.4. F Bit ..............................................21
+           3.1.5. L Bit ..............................................22
+           3.1.6. Fragment ID ........................................22
+           3.1.7. Length .............................................22
+           3.1.8. Status and WLANS ...................................22
+           3.1.9. Payload ............................................22
+      3.2. Using IEEE 802.3 MAC as LWAPP Transport ...................22
+           3.2.1. Framing ............................................23
+           3.2.2. AC Discovery .......................................23
+           3.2.3. LWAPP Message Header Format over IEEE 802.3
+                  MAC Transport ......................................23
+           3.2.4. Fragmentation/Reassembly ...........................24
+           3.2.5. Multiplexing .......................................24
+      3.3. Using IP/UDP as LWAPP Transport ...........................24
+           3.3.1. Framing ............................................24
+           3.3.2. AC Discovery .......................................25
+           3.3.3. LWAPP Message Header Format over IP/UDP Transport ..25
+           3.3.4. Fragmentation/Reassembly for IPv4 ..................26
+           3.3.5. Fragmentation/Reassembly for IPv6 ..................26
+           3.3.6. Multiplexing .......................................26
+   4. LWAPP Packet Definitions .......................................26
+      4.1. LWAPP Data Messages .......................................27
+      4.2. LWAPP Control Messages Overview ...........................27
+           4.2.1. Control Message Format .............................28
+           4.2.2. Message Element Format .............................29
+           4.2.3. Quality of Service .................................31
+   5. LWAPP Discovery Operations .....................................31
+      5.1. Discovery Request .........................................31
+           5.1.1. Discovery Type .....................................32
+           5.1.2. WTP Descriptor .....................................33
+           5.1.3. WTP Radio Information ..............................34
+      5.2. Discovery Response ........................................34
+           5.2.1. AC Address .........................................35
+           5.2.2. AC Descriptor ......................................35
+           5.2.3. AC Name ............................................36
+           5.2.4. WTP Manager Control IPv4 Address ...................37
+
+
+
+Calhoun, et al.                 Historic                        [Page 3]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+           5.2.5. WTP Manager Control IPv6 Address ...................37
+      5.3. Primary Discovery Request .................................38
+           5.3.1. Discovery Type .....................................38
+           5.3.2. WTP Descriptor .....................................38
+           5.3.3. WTP Radio Information ..............................38
+      5.4. Primary Discovery Response ................................38
+           5.4.1. AC Descriptor ......................................39
+           5.4.2. AC Name ............................................39
+           5.4.3. WTP Manager Control IPv4 Address ...................39
+           5.4.4. WTP Manager Control IPv6 Address ...................39
+   6. Control Channel Management .....................................39
+      6.1. Join Request ..............................................39
+           6.1.1. WTP Descriptor .....................................40
+           6.1.2. AC Address .........................................40
+           6.1.3. WTP Name ...........................................40
+           6.1.4. Location Data ......................................41
+           6.1.5. WTP Radio Information ..............................41
+           6.1.6. Certificate ........................................41
+           6.1.7. Session ID .........................................42
+           6.1.8. Test ...............................................42
+           6.1.9. XNonce .............................................42
+      6.2. Join Response .............................................43
+           6.2.1. Result Code ........................................44
+           6.2.2. Status .............................................44
+           6.2.3. Certificate ........................................45
+           6.2.4. WTP Manager Data IPv4 Address ......................45
+           6.2.5. WTP Manager Data IPv6 Address ......................45
+           6.2.6. AC IPv4 List .......................................46
+           6.2.7. AC IPv6 List .......................................46
+           6.2.8. ANonce .............................................47
+           6.2.9. PSK-MIC ............................................48
+      6.3. Join ACK ..................................................48
+           6.3.1. Session ID .........................................49
+           6.3.2. WNonce .............................................49
+           6.3.3. PSK-MIC ............................................49
+      6.4. Join Confirm ..............................................49
+           6.4.1. Session ID .........................................50
+           6.4.2. PSK-MIC ............................................50
+      6.5. Echo Request ..............................................50
+      6.6. Echo Response .............................................50
+      6.7. Key Update Request ........................................51
+           6.7.1. Session ID .........................................51
+           6.7.2. XNonce .............................................51
+      6.8. Key Update Response .......................................51
+           6.8.1. Session ID .........................................51
+           6.8.2. ANonce .............................................51
+           6.8.3. PSK-MIC ............................................52
+      6.9. Key Update ACK ............................................52
+
+
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+Calhoun, et al.                 Historic                        [Page 4]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+           6.9.1. WNonce .............................................52
+           6.9.2. PSK-MIC ............................................52
+      6.10. Key Update Confirm .......................................52
+           6.10.1. PSK-MIC ...........................................52
+      6.11. Key Update Trigger .......................................52
+           6.11.1. Session ID ........................................53
+   7. WTP Configuration Management ...................................53
+      7.1. Configuration Consistency .................................53
+      7.2. Configure Request .........................................54
+           7.2.1. Administrative State ...............................54
+           7.2.2. AC Name ............................................55
+           7.2.3. AC Name with Index .................................55
+           7.2.4. WTP Board Data .....................................56
+           7.2.5. Statistics Timer ...................................56
+           7.2.6. WTP Static IP Address Information ..................57
+           7.2.7. WTP Reboot Statistics ..............................58
+      7.3. Configure Response ........................................58
+           7.3.1. Decryption Error Report Period .....................59
+           7.3.2. Change State Event .................................59
+           7.3.3. LWAPP Timers .......................................60
+           7.3.4. AC IPv4 List .......................................60
+           7.3.5. AC IPv6 List .......................................61
+           7.3.6. WTP Fallback .......................................61
+           7.3.7. Idle Timeout .......................................61
+      7.4. Configuration Update Request ..............................62
+           7.4.1. WTP Name ...........................................62
+           7.4.2. Change State Event .................................62
+           7.4.3. Administrative State ...............................62
+           7.4.4. Statistics Timer ...................................62
+           7.4.5. Location Data ......................................62
+           7.4.6. Decryption Error Report Period .....................62
+           7.4.7. AC IPv4 List .......................................62
+           7.4.8. AC IPv6 List .......................................62
+           7.4.9. Add Blacklist Entry ................................63
+           7.4.10. Delete Blacklist Entry ............................63
+           7.4.11. Add Static Blacklist Entry ........................64
+           7.4.12. Delete Static Blacklist Entry .....................64
+           7.4.13. LWAPP Timers ......................................65
+           7.4.14. AC Name with Index ................................65
+           7.4.15. WTP Fallback ......................................65
+           7.4.16. Idle Timeout ......................................65
+      7.5. Configuration Update Response .............................65
+           7.5.1. Result Code ........................................65
+      7.6. Change State Event Request ................................65
+           7.6.1. Change State Event .................................66
+      7.7. Change State Event Response ...............................66
+      7.8. Clear Config Indication ...................................66
+   8. Device Management Operations ...................................66
+
+
+
+Calhoun, et al.                 Historic                        [Page 5]
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+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      8.1. Image Data Request ........................................66
+           8.1.1. Image Download .....................................67
+           8.1.2. Image Data .........................................67
+      8.2. Image Data Response .......................................68
+      8.3. Reset Request .............................................68
+      8.4. Reset Response ............................................68
+      8.5. WTP Event Request .........................................68
+           8.5.1. Decryption Error Report ............................69
+           8.5.2. Duplicate IPv4 Address .............................69
+           8.5.3. Duplicate IPv6 Address .............................70
+      8.6. WTP Event Response ........................................70
+      8.7. Data Transfer Request .....................................71
+           8.7.1. Data Transfer Mode .................................71
+           8.7.2. Data Transfer Data .................................71
+      8.8. Data Transfer Response ....................................72
+   9. Mobile Session Management ......................................72
+      9.1. Mobile Config Request .....................................72
+           9.1.1. Delete Mobile ......................................73
+      9.2. Mobile Config Response ....................................73
+           9.2.1. Result Code ........................................74
+   10. LWAPP Security ................................................74
+      10.1. Securing WTP-AC Communications ...........................74
+      10.2. LWAPP Frame Encryption ...................................75
+      10.3. Authenticated Key Exchange ...............................76
+           10.3.1. Terminology .......................................76
+           10.3.2. Initial Key Generation ............................77
+           10.3.3. Refreshing Cryptographic Keys .....................81
+      10.4. Certificate Usage ........................................82
+   11. IEEE 802.11 Binding ...........................................82
+      11.1. Division of Labor ........................................82
+           11.1.1. Split MAC .........................................83
+           11.1.2. Local MAC .........................................85
+      11.2. Roaming Behavior and 802.11 Security .....................87
+      11.3. Transport-Specific Bindings ..............................88
+           11.3.1. Status and WLANS Field ............................88
+      11.4. BSSID to WLAN ID Mapping .................................89
+      11.5. Quality of Service .......................................89
+      11.6. Data Message Bindings ....................................90
+      11.7. Control Message Bindings .................................90
+           11.7.1. Mobile Config Request .............................90
+           11.7.2. WTP Event Request .................................96
+      11.8. 802.11 Control Messages ..................................97
+           11.8.1. IEEE 802.11 WLAN Config Request ...................98
+           11.8.2. IEEE 802.11 WLAN Config Response .................103
+           11.8.3. IEEE 802.11 WTP Event ............................103
+      11.9. Message Element Bindings ................................105
+           11.9.1. IEEE 802.11 WTP WLAN Radio Configuration .........105
+           11.9.2. IEEE 802.11 Rate Set .............................107
+
+
+
+Calhoun, et al.                 Historic                        [Page 6]
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+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+           11.9.3. IEEE 802.11 Multi-Domain Capability ..............107
+           11.9.4. IEEE 802.11 MAC Operation ........................108
+           11.9.5. IEEE 802.11 Tx Power .............................109
+           11.9.6. IEEE 802.11 Tx Power Level .......................110
+           11.9.7. IEEE 802.11 Direct Sequence Control ..............110
+           11.9.8. IEEE 802.11 OFDM Control .........................111
+           11.9.9. IEEE 802.11 Antenna ..............................112
+           11.9.10. IEEE 802.11 Supported Rates .....................113
+           11.9.11. IEEE 802.11 CFP Status ..........................114
+           11.9.12. IEEE 802.11 WTP Mode and Type ...................114
+           11.9.13. IEEE 802.11 Broadcast Probe Mode ................115
+           11.9.14. IEEE 802.11 WTP Quality of Service ..............115
+           11.9.15. IEEE 802.11 MIC Error Report From Mobile ........117
+      11.10. IEEE 802.11 Message Element Values .....................117
+   12. LWAPP Protocol Timers ........................................118
+      12.1. MaxDiscoveryInterval ....................................118
+      12.2. SilentInterval ..........................................118
+      12.3. NeighborDeadInterval ....................................118
+      12.4. EchoInterval ............................................118
+      12.5. DiscoveryInterval .......................................118
+      12.6. RetransmitInterval ......................................119
+      12.7. ResponseTimeout .........................................119
+      12.8. KeyLifetime .............................................119
+   13. LWAPP Protocol Variables .....................................119
+      13.1. MaxDiscoveries ..........................................119
+      13.2. DiscoveryCount ..........................................119
+      13.3. RetransmitCount .........................................119
+      13.4. MaxRetransmit ...........................................120
+   14. NAT Considerations ...........................................120
+   15. Security Considerations ......................................121
+      15.1. Certificate-Based Session Key Establishment .............122
+      15.2. PSK-Based Session Key Establishment .....................123
+   16. Acknowledgements .............................................123
+   17. References ...................................................123
+      17.1. Normative References ....................................123
+      17.2. Informative References ..................................124
+
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+Calhoun, et al.                 Historic                        [Page 7]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+1.  Introduction
+
+   Unlike wired network elements, Wireless Termination Points (WTPs)
+   require a set of dynamic management and control functions related to
+   their primary task of connecting the wireless and wired mediums.
+   Today, protocols for managing WTPs are either manual static
+   configuration via HTTP, proprietary Layer 2-specific, or non-existent
+   (if the WTPs are self-contained).  The emergence of simple 802.11
+   WTPs that are managed by a WLAN appliance or switch (also known as an
+   Access Controller, or AC) suggests that having a standardized,
+   interoperable protocol could radically simplify the deployment and
+   management of wireless networks.  In many cases, the overall control
+   and management functions themselves are generic and could apply to an
+   AP for any wireless Layer 2 (L2) protocol.  Being independent of
+   specific wireless Layer 2 technologies, such a protocol could better
+   support interoperability between Layer 2 devices and enable smoother
+   intertechnology handovers.
+
+   The details of how these functions would be implemented are dependent
+   on the particular Layer 2 wireless technology.  Such a protocol would
+   need provisions for binding to specific technologies.
+
+   LWAPP assumes a network configuration that consists of multiple WTPs
+   communicating either via Layer 2 (Medium Access Control (MAC)) or
+   Layer 3 (IP) to an AC.  The WTPs can be considered as remote radio
+   frequency (RF) interfaces, being controlled by the AC.  The AC
+   forwards all L2 frames it wants to transmit to a WTP via the LWAPP
+   protocol.  Packets from mobile nodes are forwarded by the WTP to the
+   AC, also via this protocol.  Figure 1 illustrates this arrangement as
+   applied to an IEEE 802.11 binding.
+
+                  +-+         802.11 frames          +-+
+                  | |--------------------------------| |
+                  | |              +-+               | |
+                  | |--------------| |---------------| |
+                  | |  802.11 PHY/ | |     LWAPP     | |
+                  | | MAC sublayer | |               | |
+                  +-+              +-+               +-+
+                  STA              WTP                AC
+
+                        Figure 1: LWAPP Architecture
+
+
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+
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+Calhoun, et al.                 Historic                        [Page 8]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Security is another aspect of Wireless Termination Point management
+   that is not well served by existing solutions.  Provisioning WTPs
+   with security credentials, and managing which WTPs are authorized to
+   provide service are today handled by proprietary solutions.  Allowing
+   these functions to be performed from a centralized AC in an
+   interoperable fashion increases manageability and allows network
+   operators to more tightly control their wireless network
+   infrastructure.
+
+   This document describes the Lightweight Access Point Protocol
+   (LWAPP), allowing an AC to manage a collection of WTPs.  The protocol
+   is defined to be independent of Layer 2 technology, but an 802.11
+   binding is provided for use in growing 802.11 wireless LAN networks.
+
+   Goals:
+
+   The following are goals for this protocol:
+
+   1. Centralization of the bridging, forwarding, authentication, and
+      policy enforcement functions for a wireless network.  Optionally,
+      the AC may also provide centralized encryption of user traffic.
+      This will permit reduced cost and higher efficiency when applying
+      the capabilities of network processing silicon to the wireless
+      network, as it has already been applied to wired LANs.
+
+   2. Permit shifting of the higher-level protocol processing burden
+      away from the WTP.  This leaves the computing resource of the WTP
+      to the timing-critical applications of wireless control and
+      access.  This makes the most efficient use of the computing power
+      available in WTPs that are the subject of severe cost pressure.
+
+   3. Providing a generic encapsulation and transport mechanism, the
+      protocol may be applied to other access point types in the future
+      by adding the binding.
+
+   The LWAPP protocol concerns itself solely with the interface between
+   the WTP and the AC.  Inter-AC, or mobile-to-AC communication is
+   strictly outside the scope of this document.
+
+1.1.  Conventions Used in This Document
+
+   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
+   document are to be interpreted as described in RFC 2119 [1].
+
+
+
+
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+Calhoun, et al.                 Historic                        [Page 9]
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+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+2.  Protocol Overview
+
+   LWAPP is a generic protocol defining how Wireless Termination Points
+   communicate with Access Controllers.  Wireless Termination Points and
+   Access Controllers may communicate either by means of Layer 2
+   protocols or by means of a routed IP network.
+
+   LWAPP messages and procedures defined in this document apply to both
+   types of transports unless specified otherwise.  Transport
+   independence is achieved by defining formats for both MAC-level and
+   IP-level transport (see Section 3).  Also defined are framing,
+   fragmentation/reassembly, and multiplexing services to LWAPP for each
+   transport type.
+
+   The LWAPP Transport layer carries two types of payload.  LWAPP data
+   messages are forwarded wireless frames.  LWAPP control messages are
+   management messages exchanged between a WTP and an AC.  The LWAPP
+   transport header defines the "C-bit", which is used to distinguish
+   data and control traffic.  When used over IP, the LWAPP data and
+   control traffic are also sent over separate UDP ports.  Since both
+   data and control frames can exceed Path Maximum Transmission Unit
+   (PMTU), the payload of an LWAPP data or control message can be
+   fragmented.  The fragmentation behavior is highly dependent upon the
+   lower-layer transport and is defined in Section 3.
+
+   The Lightweight Access Protocol (LWAPP) begins with a discovery
+   phase.  The WTPs send a Discovery Request frame, causing any Access
+   Controller (AC), receiving that frame to respond with a Discovery
+   Response.  From the Discovery Responses received, a WTP will select
+   an AC with which to associate, using the Join Request and Join
+   Response.  The Join Request also provides an MTU discovery mechanism,
+   to determine whether there is support for the transport of large
+   frames between the WTP and its AC.  If support for large frames is
+   not present, the LWAPP frames will be fragmented to the maximum
+   length discovered to be supported by the network.
+
+   Once the WTP and the AC have joined, a configuration exchange is
+   accomplished that will cause both devices to agree on version
+   information.  During this exchange, the WTP may receive provisioning
+   settings.  For the 802.11 binding, this information would typically
+   include a name (802.11 Service Set Identifier, SSID), and security
+   parameters, the data rates to be advertised, as well as the radio
+   channel (channels, if the WTP is capable of operating more than one
+   802.11 MAC and Physical Layer (PHY) simultaneously) to be used.
+   Finally, the WTPs are enabled for operation.
+
+
+
+
+
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+Calhoun, et al.                 Historic                       [Page 10]
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+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   When the WTP and AC have completed the version and provision exchange
+   and the WTP is enabled, the LWAPP encapsulates the wireless frames
+   sent between them.  LWAPP will fragment its packets, if the size of
+   the encapsulated wireless user data (Data) or protocol control
+   (Management) frames cause the resultant LWAPP packet to exceed the
+   MTU supported between the WTP and AC.  Fragmented LWAPP packets are
+   reassembled to reconstitute the original encapsulated payload.
+
+   In addition to the functions thus far described, LWAPP also provides
+   for the delivery of commands from the AC to the WTP for the
+   management of devices that are communicating with the WTP.  This may
+   include the creation of local data structures in the WTP for the
+   managed devices and the collection of statistical information about
+   the communication between the WTP and the 802.11 devices.  LWAPP
+   provides the ability for the AC to obtain any statistical information
+   collected by the WTP.
+
+   LWAPP also provides for a keepalive feature that preserves the
+   communication channel between the WTP and AC.  If the AC fails to
+   appear alive, the WTP will try to discover a new AC to communicate
+   through.
+
+   This document uses terminology defined in [5].
+
+2.1.  Wireless Binding Definition
+
+   This draft standard specifies a protocol independent of a specific
+   wireless access point radio technology.  Elements of the protocol are
+   designed to accommodate specific needs of each wireless technology in
+   a standard way.  Implementation of this standard for a particular
+   wireless technology must follow the binding requirements defined for
+   that technology.  This specification includes a binding for the IEEE
+   802.11 (see Section 11).
+
+   When defining a binding for other technologies, the authors MUST
+   include any necessary definitions for technology-specific messages
+   and all technology-specific message elements for those messages.  At
+   a minimum, a binding MUST provide the definition for a binding-
+   specific Statistics message element, which is carried in the WTP
+   Event Request message, and Add Mobile message element, which is
+   carried in the Mobile Configure Request.  If any technology-specific
+   message elements are required for any of the existing LWAPP messages
+   defined in this specification, they MUST also be defined in the
+   technology-binding document.
+
+   The naming of binding-specific message elements MUST begin with the
+   name of the technology type, e.g., the binding for IEEE 802.11,
+   provided in this standard, begins with "IEEE 802.11".
+
+
+
+Calhoun, et al.                 Historic                       [Page 11]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+2.2.  LWAPP State Machine Definition
+
+   The following state diagram represents the life cycle of a WTP-AC
+   session:
+
+      /-------------\
+      |             v
+      |       +------------+
+      |      C|    Idle    |<-----------------------------------\
+      |       +------------+<-----------------------\           |
+      |        ^    |a    ^                         |           |
+      |        |    |     \----\                    |           |
+      |        |    |          |                 +------------+ |
+      |        |    |          |          -------| Key Confirm| |
+      |        |    |          |        w/       +------------+ |
+      |        |    |          |        |           ^           |
+      |        |    |          |t       V           |5          |
+      |        |    |        +-----------+       +------------+ |
+      |       /     |       C|    Run    |       | Key Update | |
+      |     /       |       r+-----------+------>+------------+ |
+      |    /        |              ^    |s      u        x|     |
+      |   |         v              |    |                 |     |
+      |   |   +--------------+     |    |                 v     |y
+      |   |  C|  Discovery   |    q|    \--------------->+-------+
+      |   |  b+--------------+    +-------------+        | Reset |
+      |   |     |d     f|  ^      |  Configure  |------->+-------+
+      |   |     |       |  |      +-------------+p           ^
+      |   |e    v       |  |              ^                  |
+      |  +---------+    v  |i            2|                  |
+      | C| Sulking |   +------------+    +--------------+    |
+      |  +---------+  C|    Join    |--->| Join-Confirm |    |
+      |               g+------------+z   +--------------+    |
+      |                   |h      m|        3|       |4      |
+      |                   |        |         |       v       |o
+      |\                  |        |         |     +------------+
+       \\-----------------/         \--------+---->| Image Data |C
+        \------------------------------------/     +------------+n
+
+                        Figure 2: LWAPP State Machine
+
+   The LWAPP state machine, depicted above, is used by both the AC and
+   the WTP.  For every state defined, only certain messages are
+   permitted to be sent and received.  In all of the LWAPP control
+   messages defined in this document, the state for which each command
+   is valid is specified.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 12]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Note that in the state diagram figure above, the 'C' character is
+   used to represent a condition that causes the state to remain the
+   same.
+
+   The following text discusses the various state transitions, and the
+   events that cause them.
+
+   Idle to Discovery (a):  This is the initialization state.
+
+      WTP:  The WTP enters the Discovery state prior to transmitting the
+            first Discovery Request (see Section 5.1).  Upon entering
+            this state, the WTP sets the DiscoveryInterval timer (see
+            Section 12).  The WTP resets the DiscoveryCount counter to
+            zero (0) (see Section 13).  The WTP also clears all
+            information from ACs (e.g., AC Addresses) it may have
+            received during a previous discovery phase.
+
+       AC:  The AC does not need to maintain state information for the
+            WTP upon reception of the Discovery Request, but it MUST
+            respond with a Discovery Response (see Section 5.2).
+
+   Discovery to Discovery (b):  This is the state the WTP uses to
+   determine to which AC it wishes to connect.
+
+      WTP:  This event occurs when the DiscoveryInterval timer expires.
+            The WTP transmits a Discovery Request to every AC to which
+            the WTP hasn't received a response.  For every transition to
+            this event, the WTP increments the DisoveryCount counter.
+            See Section 5.1 for more information on how the WTP knows to
+            which ACs it should transmit the Discovery Requests.  The
+            WTP restarts the DiscoveryInterval timer.
+
+       AC:  This is a noop.
+
+   Discovery to Sulking (d):  This state occurs on a WTP when Discovery
+   or connectivity to the AC fails.
+
+      WTP:  The WTP enters this state when the DiscoveryInterval timer
+            expires and the DiscoveryCount variable is equal to the
+            MaxDiscoveries variable (see Section 13).  Upon entering
+            this state, the WTP will start the SilentInterval timer.
+            While in the Sulking state, all LWAPP messages received are
+            ignored.
+
+       AC:  This is a noop.
+
+   Sulking to Idle (e):  This state occurs on a WTP when it must restart
+   the discovery phase.
+
+
+
+Calhoun, et al.                 Historic                       [Page 13]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      WTP:  The WTP enters this state when the SilentInterval timer (see
+            Section 12) expires.
+
+       AC:  This is a noop.
+
+   Discovery to Join (f):  This state is used by the WTP to confirm its
+   commitment to an AC that it wishes to be provided service.
+
+      WTP:  The WTP selects the best AC based on the information it
+            gathered during the discovery phase.  It then transmits a
+            Join Request (see Section 6.1) to its preferred AC.  The WTP
+            starts the WaitJoin timer (see Section 12).
+
+       AC:  The AC enters this state for the given WTP upon reception of
+            a Join Request.  The AC processes the request and responds
+            with a Join Response.
+
+   Join to Join (g):  This state transition occurs during the join
+   phase.
+
+      WTP:  The WTP enters this state when the WaitJoin timer expires,
+            and the underlying transport requires LWAPP MTU detection
+            (Section 3).
+
+       AC:  This state occurs when the AC receives a retransmission of a
+            Join Request.  The WTP processes the request and responds
+            with the Join Response.
+
+   Join to Idle (h):  This state is used when the join process has
+   failed.
+
+      WTP:  This state transition occurs if the WTP is configured to use
+            pre-shared key (PSK) security and receives a Join Response
+            that includes an invalid PSK-MIC (Message Integrity Check)
+            message element.
+
+       AC:  The AC enters this state when it transmits an unsuccessful
+            Join Response.
+
+   Join to Discovery (i):  This state is used when the join process has
+   failed.
+
+      WTP:  The WTP enters this state when it receives an unsuccessful
+            Join Response.  Upon entering this state, the WTP sets the
+            DiscoveryInterval timer (see Section 12).  The WTP resets
+            the DiscoveryCount counter to zero (0) (see Section 13).
+            This state transition may also occur if the PSK-MIC (see
+            Section 6.2.9) message element is invalid.
+
+
+
+Calhoun, et al.                 Historic                       [Page 14]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       AC:  This state transition is invalid.
+
+   Join to Join-Confirm (z):  This state is used to provide key
+   confirmation during the join process.
+
+      WTP:  This state is entered when the WTP receives a Join Response.
+            In the event that certificate-based security is utilized,
+            this transition will occur if the Certificate message
+            element is present and valid in the Join Response.  For pre-
+            shared key security, the Join Response must include a valid
+            and authenticated PSK-MIC message element.  The WTP MUST
+            respond with a Join ACK, which is used to provide key
+            confirmation.
+
+       AC:  The AC enters this state when it receives a valid Join ACK.
+            For certificate-based security, the Join ACK MUST include
+            the WNonce message element.  For pre-shared key security,
+            the message must include a valid PSK-MIC message element.
+            The AC MUST respond with a Join Confirm message, which
+            includes the Session Key message element.
+
+   Join-Confirm to Idle (3):  This state is used when the join process
+   has failed.
+
+      WTP:  This state transition occurs when the WTP receives an
+            invalid Join Confirm.
+
+       AC:  The AC enters this state when it receives an invalid Join
+            ACK.
+
+   Join-Confirm to Configure (2):  This state is used by the WTP and the
+   AC to exchange configuration information.
+
+      WTP:  The WTP enters this state when it receives a successful Join
+            Confirm and determines that its version number and the
+            version number advertised by the AC are the same.  The WTP
+            transmits the Configure Request (see Section 7.2) message to
+            the AC with a snapshot of its current configuration.  The
+            WTP also starts the ResponseTimeout timer (see Section 12).
+
+       AC:  This state transition occurs when the AC receives the
+            Configure Request from the WTP.  The AC must transmit a
+            Configure Response (see Section 7.3) to the WTP, and may
+            include specific message elements to override the WTP's
+            configuration.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 15]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Join-Confirm to Image Data (4):  This state is used by the WTP and
+   the AC to download executable firmware.
+
+      WTP:  The WTP enters this state when it receives a successful Join
+            Confirm, and determines that its version number and the
+            version number advertised by the AC are different.  The WTP
+            transmits the Image Data Request (see Section 8.1) message
+            requesting that the AC's latest firmware be initiated.
+
+       AC:  This state transition occurs when the AC receives the Image
+            Data Request from the WTP.  The AC must transmit an Image
+            Data Response (see Section 8.2) to the WTP, which includes a
+            portion of the firmware.
+
+   Image Data to Image Data (n):  This state is used by the WTP and the
+   AC during the firmware download phase.
+
+      WTP:  The WTP enters this state when it receives an Image Data
+            Response that indicates that the AC has more data to send.
+
+       AC:  This state transition occurs when the AC receives the Image
+            Data Request from the WTP while already in this state, and
+            it detects that the firmware download has not completed.
+
+   Image Data to Reset (o):  This state is used when the firmware
+   download is completed.
+
+      WTP:  The WTP enters this state when it receives an Image Data
+            Response that indicates that the AC has no more data to
+            send, or if the underlying LWAPP transport indicates a link
+            failure.  At this point, the WTP reboots itself.
+
+       AC:  This state transition occurs when the AC receives the Image
+            Data Request from the WTP while already in this state, and
+            it detects that the firmware download has completed or if
+            the underlying LWAPP transport indicates a link failure.
+            Note that the AC itself does not reset, but it places the
+            specific WTP's context it is communicating with in the reset
+            state: meaning that it clears all state associated with the
+            WTP.
+
+   Configure to Reset (p):  This state transition occurs if the
+   configure phase fails.
+
+      WTP:  The WTP enters this state when the reliable transport fails
+            to deliver the Configure Request, or if the ResponseTimeout
+            timer (see Section 12) expires.
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 16]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       AC:  This state transition occurs if the AC is unable to transmit
+            the Configure Response to a specific WTP.  Note that the AC
+            itself does not reset, but it places the specific WTP's
+            context it is communicating with in the reset state: meaning
+            that it clears all state associated with the WTP.
+
+   Configure to Run (q):  This state transition occurs when the WTP and
+   AC enter their normal state of operation.
+
+      WTP:  The WTP enters this state when it receives a successful
+            Configure Response from the AC.  The WTP initializes the
+            HeartBeat timer (see Section 12), and transmits the Change
+            State Event Request message (see Section 7.6).
+
+       AC:  This state transition occurs when the AC receives the Change
+            State Event Request (see Section 7.6) from the WTP.  The AC
+            responds with a Change State Event Response (see Section
+            7.7) message.  The AC must start the Session ID and
+            NeighborDead timers (see Section 12).
+
+   Run to Run (r):  This is the normal state of operation.
+
+      WTP:  This is the WTP's normal state of operation, and there are
+            many events that cause this to occur:
+
+         Configuration Update:  The WTP receives a Configuration Update
+         Request (see Section 7.4).  The WTP MUST respond with a
+         Configuration Update Response (see Section 7.5).
+
+         Change State Event:  The WTP receives a Change State Event
+         Response, or determines that it must initiate a Change State
+         Event Request, as a result of a failure or change in the state
+         of a radio.
+
+         Echo Request:  The WTP receives an Echo Request message
+         (Section 6.5), to which it MUST respond with an Echo Response
+         (see Section 6.6).
+
+         Clear Config Indication:  The WTP receives a Clear Config
+         Indication message (Section 7.8).  The WTP MUST reset its
+         configuration back to manufacturer defaults.
+
+         WTP Event:  The WTP generates a WTP Event Request to send
+         information to the AC (Section 8.5).  The WTP receives a WTP
+         Event Response from the AC (Section 8.6).
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 17]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+         Data Transfer:  The WTP generates a Data Transfer Request to
+         the AC (Section 8.7).  The WTP receives a Data Transfer
+         Response from the AC (Section 8.8).
+
+         WLAN Config Request:  The WTP receives a WLAN Config Request
+         message (Section 11.8.1), to which it MUST respond with a WLAN
+         Config Response (see Section 11.8.2).
+
+         Mobile Config Request:  The WTP receives an Mobile Config
+         Request message (Section 9.1), to which it MUST respond with a
+         Mobile Config Response (see Section 9.2).
+
+       AC:  This is the AC's normal state of operation, and there are
+            many events that cause this to occur:
+
+         Configuration Update:  The AC sends a Configuration Update
+         Request (see Section 7.4) to the WTP to update its
+         configuration.  The AC receives a Configuration Update Response
+         (see Section 7.5) from the WTP.
+
+         Change State Event:  The AC receives a Change State Event
+         Request (see Section 7.6), to which it MUST respond with the
+         Change State Event Response (see Section 7.7).
+
+         Echo:  The AC sends an Echo Request message (Section 6.5) or
+         receives the associated Echo Response (see Section 6.6) from
+         the WTP.
+
+         Clear Config Indication:  The AC sends a Clear Config
+         Indication message (Section 7.8).
+
+         WLAN Config:  The AC sends a WLAN Config Request message
+         (Section 11.8.1) or receives the associated WLAN Config
+         Response (see Section 11.8.2) from the WTP.
+
+         Mobile Config:  The AC sends a Mobile Config Request message
+         (Section 9.1) or receives the associated Mobile Config Response
+         (see Section 9.2) from the WTP.
+
+         Data Transfer:  The AC receives a Data Transfer Request from
+         the AC (see Section 8.7) and MUST generate the associated Data
+         Transfer Response message (see Section 8.8).
+
+         WTP Event:  The AC receives a WTP Event Request from the AC
+         (see Section 8.5) and MUST generate the associated WTP Event
+         Response message (see Section 8.6).
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 18]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Run to Reset (s):  This event occurs when the AC wishes for the WTP
+   to reboot.
+
+      WTP:  The WTP enters this state when it receives a Reset Request
+            (see Section 8.3).  It must respond with a Reset Response
+            (see Section 8.4), and once the reliable transport
+            acknowledgement has been received, it must reboot itself.
+
+       AC:  This state transition occurs either through some
+            administrative action, or via some internal event on the AC
+            that causes it to request that the WTP disconnect.  Note
+            that the AC itself does not reset, but it places the
+            specific WTPs context it is communicating with in the reset
+            state.
+
+   Run to Idle (t):  This event occurs when an error occurs in the
+   communication between the WTP and the AC.
+
+      WTP:  The WTP enters this state when the underlying reliable
+            transport is unable to transmit a message within the
+            RetransmitInterval timer (see Section 12), and the maximum
+            number of RetransmitCount counter has reached the
+            MaxRetransmit variable (see Section 13).
+
+       AC:  The AC enters this state when the underlying reliable
+            transport in unable to transmit a message within the
+            RetransmitInterval timer (see Section 12), and the maximum
+            number of RetransmitCount counter has reached the
+            MaxRetransmit variable (see Section 13).
+
+   Run to Key Update (u):  This event occurs when the WTP and the AC are
+   to exchange new keying material, with which it must use to protect
+   all future messages.
+
+      WTP:  This state transition occurs when the KeyLifetime timer
+            expires (see Section 12).
+
+       AC:  The WTP enters this state when it receives a Key Update
+            Request (see Section 6.7).
+
+   Key Update to Key Confirm (w):  This event occurs during the rekey
+   phase and is used to complete the loop.
+
+      WTP:  This state transition occurs when the WTP receives the Key
+            Update Response.  The WTP MUST only accept the message if it
+            is authentic.  The WTP responds to this response with a Key
+            Update ACK.
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 19]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       AC:  The AC enters this state when it receives an authenticated
+            Key Update ACK message.
+
+   Key Confirm to Run (5):  This event occurs when the rekey exchange
+   phase is completed.
+
+      WTP:  This state transition occurs when the WTP receives the Key
+            Update Confirm.  The newly derived encryption key and
+            Initialization Vector (IV) must be plumbed into the crypto
+            module after validating the message's authentication.
+
+       AC:  The AC enters this state when it transmits the Key Update
+            Confirm message.  The newly derived encryption key and IV
+            must be plumbed into the crypto module after transmitting a
+            Key Update Confirm message.
+
+   Key Update to Reset (x):  This event occurs when the key exchange
+   phase times out.
+
+      WTP:  This state transition occurs when the WTP does not receive a
+            Key Update Response from the AC.
+
+       AC:  The AC enters this state when it is unable to process a Key
+            Update Request.
+
+   Reset to Idle (y):  This event occurs when the state machine is
+   restarted.
+
+      WTP:  The WTP reboots itself.  After rebooting, the WTP will start
+            its LWAPP state machine in the Idle state.
+
+       AC:  The AC clears out any state associated with the WTP.  The AC
+            generally does this as a result of the reliable link layer
+            timing out.
+
+3.  LWAPP Transport Layers
+
+   The LWAPP protocol can operate at Layer 2 or 3.  For Layer 2 support,
+   the LWAPP messages are carried in a native Ethernet frame.  As such,
+   the protocol is not routable and depends upon Layer 2 connectivity
+   between the WTP and the AC.  Layer 3 support is provided by
+   encapsulating the LWAPP messages within UDP.
+
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 20]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+3.1.  LWAPP Transport Header
+
+   All LWAPP protocol packets are encapsulated using a common header
+   format, regardless of the transport used to carry the frames.
+   However, certain flags are not applicable for a given transport, and
+   it is therefore necessary to refer to the specific transport section
+   in order to determine which flags are valid.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |VER| RID |C|F|L|    Frag ID    |            Length             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |          Status/WLANs         |   Payload...  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+3.1.1.  VER Field
+
+   A 2-bit field that contains the version of LWAPP used in this packet.
+   The value for this document is 0.
+
+3.1.2.  RID Field
+
+   A 3-bit field that contains the Radio ID number for this packet.
+   WTPs with multiple radios but a single MAC address use this field to
+   indicate which radio is associated with the packet.
+
+3.1.3.  C Bit
+
+   The control message 'C' bit indicates whether this packet carries a
+   data or control message.  When this bit is zero (0), the packet
+   carries an LWAPP data message in the payload (see Section 4.1).  When
+   this bit is one (1), the packet carries an LWAPP control message as
+   defined in Section 4.2 for consumption by the addressed destination.
+
+3.1.4.  F Bit
+
+   The Fragment 'F' bit indicates whether this packet is a fragment.
+   When this bit is one (1), the packet is a fragment and MUST be
+   combined with the other corresponding fragments to reassemble the
+   complete information exchanged between the WTP and AC.
+
+
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 21]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+3.1.5.  L Bit
+
+   The Not Last 'L' bit is valid only if the 'F' bit is set and
+   indicates whether the packet contains the last fragment of a
+   fragmented exchange between the WTP and AC.  When this bit is 1, the
+   packet is not the last fragment.  When this bit is 0, the packet is
+   the last fragment.
+
+3.1.6.  Fragment ID
+
+   An 8-bit field whose value is assigned to each group of fragments
+   making up a complete set.  The Fragment ID space is managed
+   individually for every WTP/AC pair.  The value of Fragment ID is
+   incremented with each new set of fragments.  The Fragment ID wraps to
+   zero after the maximum value has been used to identify a set of
+   fragments.  LWAPP only supports up to 2 fragments per frame.
+
+3.1.7.  Length
+
+   The 16-bit length field contains the number of bytes in the Payload.
+   The field is encoded as an unsigned number.  If the LWAPP packet is
+   encrypted, the length field includes the Advanced Encryption Standard
+   Counter with CBC-MAC (AES-CCM) MIC (see Section 10.2 for more
+   information).
+
+3.1.8.  Status and WLANS
+
+   The interpretation of this 16-bit field is binding-specific.  Refer
+   to the transport portion of the binding for a wireless technology for
+   the specification.
+
+3.1.9.  Payload
+
+   This field contains the header for an LWAPP data message or LWAPP
+   control message, followed by the data associated with that message.
+
+3.2.  Using IEEE 802.3 MAC as LWAPP Transport
+
+   This section describes how the LWAPP protocol is provided over native
+   Ethernet frames.  An LWAPP packet is formed from the MAC frame
+   header, followed by the LWAPP message header.  The following figure
+   provides an example of the frame formats used when LWAPP is used over
+   the IEEE 802.3 transport.
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 22]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      Layer 2 LWAPP Data Frame
+      +-----------------------------------------------------------+
+      | MAC Header | LWAPP Header [C=0] | Forwarded Data ...      |
+      +-----------------------------------------------------------+
+
+      Layer 2 LWAPP Control Frame
+      +---------------------------------------------------+
+      | MAC Header | LWAPP Header [C=1] | Control Message |
+      +---------------------------------------------------+
+      | Message Elements ... |
+      +----------------------+
+
+3.2.1.  Framing
+
+   Source Address
+
+   A MAC address belonging to the interface from which this message is
+   sent.  If multiple source addresses are configured on an interface,
+   then the one chosen is implementation-dependent.
+
+   Destination Address
+
+   A MAC address belonging to the interface to which this message is to
+   be sent.  This destination address MAY be either an individual
+   address or a multicast address, if more than one destination
+   interface is intended.
+
+   Ethertype
+
+   The Ethertype field is set to 0x88bb.
+
+3.2.2.  AC Discovery
+
+   When run over IEEE 802.3, LWAPP messages are distributed to a
+   specific MAC-level broadcast domain.  The AC discovery mechanism used
+   with this transport is for a WTP to transmit a Discovery Request
+   message to a broadcast destination MAC address.  The ACs will receive
+   this message and reply based on their policy.
+
+3.2.3.  LWAPP Message Header Format over IEEE 802.3 MAC Transport
+
+   All of the fields described in Section 3.1 are used when LWAPP uses
+   the IEEE 802.3 MAC transport.
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 23]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+3.2.4.  Fragmentation/Reassembly
+
+   Fragmentation at the MAC layer is managed using the F, L, and Frag ID
+   fields of the LWAPP message header.  The LWAPP protocol only allows a
+   single packet to be fragmented into 2, which is sufficient for a
+   frame that exceeds MTU due to LWAPP encapsulation.  When used with
+   Layer 2 (Ethernet) transport, both fragments MUST include the LWAPP
+   header.
+
+3.2.5.  Multiplexing
+
+   LWAPP control messages and data messages are distinguished by the 'C'
+   bit in the LWAPP message header.
+
+3.3.  Using IP/UDP as LWAPP Transport
+
+   This section defines how LWAPP makes use of IP/UDP transport between
+   the WTP and the AC.  When this transport is used, the MAC layer is
+   controlled by the IP stack, and there are therefore no special MAC-
+   layer requirements.  The following figure provides an example of the
+   frame formats used when LWAPP is used over the IP/UDP transport.  IP
+   stacks can be either IPv4 or IPv6.
+
+      Layer 3 LWAPP Data Frame
+      +--------------------------------------------+
+      | MAC Header | IP | UDP | LWAPP Header [C=0] |
+      +--------------------------------------------+
+      |Forwarded Data ... |
+      +-------------------+
+
+      Layer 3 LWAPP Control Frame
+      +--------------------------------------------+
+      | MAC Header | IP | UDP | LWAPP Header [C=1] |
+      +--------------------------------------------+
+      | Control Message | Message Elements ... |
+      +-----------------+----------------------+
+
+3.3.1.  Framing
+
+   Communication between the WTP and AC is established according to the
+   standard UDP client/server model.  The connection is initiated by the
+   WTP (client) to the well-known UDP port of the AC (server) used for
+   control messages.  This UDP port number of the AC is 12222 for LWAPP
+   data and 12223 for LWAPP control frames.
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 24]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+3.3.2.  AC Discovery
+
+   When LWAPP is run over routed IP networks, the WTP and the AC do not
+   need to reside in the same IP subnet (broadcast domain).  However, in
+   the event the peers reside on separate subnets, there must exist a
+   mechanism for the WTP to discover the AC.
+
+   As the WTP attempts to establish communication with the AC, it sends
+   the Discovery Request message and receives the corresponding response
+   message from the AC.  The WTP must send the Discovery Request message
+   to either the limited broadcast IP address (255.255.255.255), a well
+   known multicast address, or the unicast IP address of the AC.  Upon
+   receipt of the message, the AC issues a Discovery Response message to
+   the unicast IP address of the WTP, regardless of whether a Discovery
+   Request was sent as a broadcast, multicast, or unicast message.
+
+   Whether the WTP uses a limited IP broadcast, multicast or unicast IP
+   address is implementation-dependent.
+
+   In order for a WTP to transmit a Discovery Request to a unicast
+   address, the WTP must first obtain the IP address of the AC.  Any
+   static configuration of an AC's IP address on the WTP non-volatile
+   storage is implementation-dependent.  However, additional dynamic
+   schemes are possible: for example:
+
+   DHCP:  A comma-delimited, ASCII-encoded list of AC IP addresses is
+          embedded inside a DHCP vendor-specific option 43 extension.
+          An example of the actual format of the vendor-specific payload
+          for IPv4 is of the form "10.1.1.1, 10.1.1.2".
+
+    DNS:  The DNS name "LWAPP-AC-Address" MAY be resolvable to one or
+          more AC addresses.
+
+3.3.3.  LWAPP Message Header Format over IP/UDP Transport
+
+   All of the fields described in Section 3.1 are used when LWAPP uses
+   the IPv4/UDP or IPv6/UDP transport, with the following exceptions.
+
+3.3.3.1.  F Bit
+
+   This flag field is not used with this transport, and MUST be set to
+   zero.
+
+3.3.3.2.  L Bit
+
+   This flag field is not used with this transport, and MUST be set to
+   zero.
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 25]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+3.3.3.3.  Frag ID
+
+   This field is not used with this transport, and MUST be set to zero.
+
+3.3.4.  Fragmentation/Reassembly for IPv4
+
+   When LWAPP is implemented at L3, the transport layer uses IP
+   fragmentation to fragment and reassemble LWAPP messages that are
+   longer than the MTU size used by either the WTP or AC.  The details
+   of IP fragmentation are covered in [8].  When used with the IP
+   transport, only the first fragment would include the LWAPP header.
+
+3.3.5.  Fragmentation/Reassembly for IPv6
+
+   IPv6 does MTU discovery so fragmentation and re-assembly is not
+   necessary for UDP packets.
+
+3.3.6.  Multiplexing
+
+   LWAPP messages convey control information between WTP and AC, as well
+   as binding specific data frames or binding specific management
+   frames.  As such, LWAPP messages need to be multiplexed in the
+   transport sub-layer and be delivered to the proper software entities
+   in the endpoints of the protocol.  However, the 'C' bit is still used
+   to differentiate between data and control frames.
+
+   In case of Layer 3 connection, multiplexing is achieved by use of
+   different UDP ports for control and data packets (see Section 3.3.1).
+
+   As part of the Join procedure, the WTP and AC may negotiate different
+   IP Addresses for data or control messages.  The IP address returned
+   in the AP Manager Control IP Address message element is used to
+   inform the WTP with the IP address to which it must send all control
+   frames.  The AP Manager Data IP Address message element MAY be
+   present only if the AC has a different IP address that the WTP is to
+   use to send its data LWAPP frames.
+
+   In the event the WTP and AC are separated by a NAT, with the WTP
+   using private IP address space, it is the responsibility of the NAT
+   to manage appropriate UDP port mapping.
+
+4.  LWAPP Packet Definitions
+
+   This section contains the packet types and format.  The LWAPP
+   protocol is designed to be transport-agnostic by specifying packet
+   formats for both MAC frames and IP packets.  An LWAPP packet consists
+   of an LWAPP Transport Layer packet header followed by an LWAPP
+   message.
+
+
+
+Calhoun, et al.                 Historic                       [Page 26]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Transport details can be found in Section 3.
+
+4.1.  LWAPP Data Messages
+
+   An LWAPP data message is a forwarded wireless frame.  When forwarding
+   wireless frames, the sender simply encapsulates the wireless frame in
+   an LWAPP data packet, using the appropriate transport rules defined
+   in Section 3.
+
+   In the event that the encapsulated frame would exceed the transport
+   layer's MTU, the sender is responsible for the fragmentation of the
+   frame, as specified in the transport-specific section of Section 3.
+
+   The actual format of the encapsulated LWAPP data frame is subject to
+   the rules defined under the specific wireless technology binding.
+
+4.2.  LWAPP Control Messages Overview
+
+   The LWAPP Control protocol provides a control channel between the WTP
+   and the AC.  The control channel is the series of control messages
+   between the WTP and AC, associated with a session ID and key.
+   Control messages are divided into the following distinct message
+   types:
+
+   Discovery:  LWAPP Discovery messages are used to identify potential
+      ACs, their load and capabilities.
+
+   Control Channel Management:  Messages that fall within this
+      classification are used for the discovery of ACs by the WTPs as
+      well as the establishment and maintenance of an LWAPP control
+      channel.
+
+   WTP Configuration:  The WTP Configuration messages are used by the AC
+      to push a specific configuration to the WTPs with which it has a
+      control channel.  Messages that deal with the retrieval of
+      statistics from the WTP also fall in this category.
+
+   Mobile Session Management:  Mobile Session Management messages are
+      used by the AC to push specific mobile policies to the WTP.
+
+   Firmware Management:  Messages in this category are used by the AC to
+      push a new firmware image down to the WTP.
+
+   Control Channel, WTP Configuration, and Mobile Session Management
+   MUST be implemented.  Firmware Management MAY be implemented.
+
+   In addition, technology-specific bindings may introduce new control
+   channel commands that depart from the above list.
+
+
+
+Calhoun, et al.                 Historic                       [Page 27]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+4.2.1.  Control Message Format
+
+   All LWAPP control messages are sent encapsulated within the LWAPP
+   header (see Section 3.1).  Immediately following the header is the
+   LWAPP control header, which has the following format:
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  Message Type |    Seq Num    |      Msg Element Length       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           Session ID                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      Msg Element [0..N]       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+4.2.1.1.  Message Type
+
+   The Message Type field identifies the function of the LWAPP control
+   message.  The valid values for a Message Type are the following:
+
+                  Description                       Value
+                  Discovery Request                    1
+                  Discovery Response                   2
+                  Join Request                         3
+                  Join Response                        4
+                  Join ACK                             5
+                  Join Confirm                         6
+                  Unused                             7-9
+                  Configure Request                   10
+                  Configure Response                  11
+                  Configuration Update Request        12
+                  Configuration Update Response       13
+                  WTP Event Request                   14
+                  WTP Event Response                  15
+                  Change State Event Request          16
+                  Change State Event Response         17
+                  Unused                           18-21
+                  Echo Request                        22
+                  Echo Response                       23
+                  Image Data Request                  24
+                  Image Data Response                 25
+                  Reset Request                       26
+                  Reset Response                      27
+                  Unused                           28-29
+                  Key Update Request                  30
+                  Key Update Response                 31
+                  Primary Discovery Request           32
+
+
+
+Calhoun, et al.                 Historic                       [Page 28]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+                  Primary Discovery Response          33
+                  Data Transfer Request               34
+                  Data Transfer Response              35
+                  Clear Config Indication             36
+                  WLAN Config Request                 37
+                  WLAN Config Response                38
+                  Mobile Config Request               39
+                  Mobile Config Response              40
+
+4.2.1.2.  Sequence Number
+
+   The Sequence Number field is an identifier value to match request/
+   response packet exchanges.  When an LWAPP packet with a request
+   message type is received, the value of the Sequence Number field is
+   copied into the corresponding response packet.
+
+   When an LWAPP control frame is sent, its internal sequence number
+   counter is monotonically incremented, ensuring that no two requests
+   pending have the same sequence number.  This field will wrap back to
+   zero.
+
+4.2.1.3.  Message Element Length
+
+   The length field indicates the number of bytes following the Session
+   ID field.  If the LWAPP packet is encrypted, the length field
+   includes the AES-CCM MIC (see Section 10.2 for more information).
+
+4.2.1.4.  Session ID
+
+   The Session ID is a 32-bit unsigned integer that is used to identify
+   the security context for encrypted exchanges between the WTP and the
+   AC.  Note that a Session ID is a random value that MUST be unique
+   between a given AC and any of the WTPs with which it may be
+   communicating.
+
+4.2.1.5.  Message Element [0..N]
+
+   The message element(s) carry the information pertinent to each of the
+   control message types.  Every control message in this specification
+   specifies which message elements are permitted.
+
+4.2.2.  Message Element Format
+
+   The message element is used to carry information pertinent to a
+   control message.  Every message element is identified by the Type
+   field, whose numbering space is managed via IANA (see Section 16).
+   The total length of the message elements is indicated in the Message
+   Element Length field.
+
+
+
+Calhoun, et al.                 Historic                       [Page 29]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   All of the message element definitions in this document use a diagram
+   similar to the one below in order to depict their formats.  Note that
+   in order to simplify this specification, these diagrams do not
+   include the header fields (Type and Length).  However, in each
+   message element description, the header's field values will be
+   defined.
+
+   Note that additional message elements may be defined in separate IETF
+   documents.
+
+   The format of a message element uses the TLV format shown here:
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      Type     |             Length            |   Value ...   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   where Type (8 bits) identifies the character of the information
+   carried in the Value field and Length (16 bits) indicates the number
+   of bytes in the Value field.
+
+4.2.2.1.  Generic Message Elements
+
+   This section includes message elements that are not bound to a
+   specific control message.
+
+4.2.2.1.1.  Vendor Specific
+
+   The Vendor-Specific Payload is used to communicate vendor-specific
+   information between the WTP and the AC.  The value contains the
+   following format:
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       Vendor Identifier                       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |          Element ID           |   Value...    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   104 for Vendor Specific
+
+   Length:   >= 7
+
+   Vendor Identifier:   A 32-bit value containing the IANA-assigned "SMI
+      Network Management Private Enterprise Codes" [13].
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 30]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Element ID:   A 16-bit Element Identifier that is managed by the
+      vendor.
+
+   Value:   The value associated with the vendor-specific element.
+
+4.2.3.  Quality of Service
+
+   It is recommended that LWAPP control messages be sent by both the AC
+   and the WTP with an appropriate Quality-of-Service precedence value,
+   ensuring that congestion in the network minimizes occurrences of
+   LWAPP control channel disconnects.  Therefore, a Quality-of-Service-
+   enabled LWAPP device should use:
+
+   802.1P:   The precedence value of 7 SHOULD be used.
+
+   DSCP:   The Differentiated Services Code Point (DSCP) tag value of 46
+           SHOULD be used.
+
+5.  LWAPP Discovery Operations
+
+   The Discovery messages are used by a WTP to determine which ACs are
+   available to provide service, as well as the capabilities and load of
+   the ACs.
+
+5.1.  Discovery Request
+
+   The Discovery Request is used by the WTP to automatically discover
+   potential ACs available in the network.  A WTP must transmit this
+   command even if it has a statically configured AC, as it is a
+   required step in the LWAPP state machine.
+
+   Discovery Requests MUST be sent by a WTP in the Discover state after
+   waiting for a random delay less of than MaxDiscoveryInterval, after a
+   WTP first comes up or is (re)initialized.  A WTP MUST send no more
+   than a maximum of MaxDiscoveries discoveries, waiting for a random
+   delay less than MaxDiscoveryInterval between each successive
+   discovery.
+
+   This is to prevent an explosion of WTP Discoveries.  An example of
+   this occurring would be when many WTPs are powered on at the same
+   time.
+
+   Discovery Requests MUST be sent by a WTP when no Echo Responses are
+   received for NeighborDeadInterval and the WTP returns to the Idle
+   state.  Discovery Requests are sent after NeighborDeadInterval, they
+   MUST be sent after waiting for a random delay less than
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 31]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   MaxDiscoveryInterval.  A WTP MAY send up to a maximum of
+   MaxDiscoveries discoveries, waiting for a random delay less than
+   MaxDiscoveryInterval between each successive discovery.
+
+   If a Discovery Response is not received after sending the maximum
+   number of Discovery Requests, the WTP enters the Sulking state and
+   MUST wait for an interval equal to SilentInterval before sending
+   further Discovery Requests.
+
+   The Discovery Request message may be sent as a unicast, broadcast, or
+   multicast message.
+
+   Upon receiving a Discovery Request, the AC will respond with a
+   Discovery Response sent to the address in the source address of the
+   received Discovery Request.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+5.1.1.  Discovery Type
+
+   The Discovery message element is used to configure a WTP to operate
+   in a specific mode.
+
+       0
+       0 1 2 3 4 5 6 7
+      +-+-+-+-+-+-+-+-+
+      | Discovery Type|
+      +-+-+-+-+-+-+-+-+
+
+   Type:   58 for Discovery Type
+
+   Length:   1
+
+   Discovery Type:   An 8-bit value indicating how the AC was
+      discovered.  The following values are supported:
+
+      0 -  Broadcast
+
+      1 -  Configured
+
+
+
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 32]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+5.1.2.  WTP Descriptor
+
+   The WTP Descriptor message element is used by the WTP to communicate
+   its current hardware/firmware configuration.  The value contains the
+   following fields.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                      Hardware   Version                       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                      Software   Version                       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          Boot   Version                       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Max Radios  | Radios in use |    Encryption Capabilities    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   3 for WTP Descriptor
+
+   Length:   16
+
+   Hardware Version:   A 32-bit integer representing the WTP's hardware
+      version number.
+
+   Software Version:   A 32-bit integer representing the WTP's Firmware
+      version number.
+
+   Boot Version:   A 32-bit integer representing the WTP's boot loader's
+      version number.
+
+   Max Radios:   An 8-bit value representing the number of radios (where
+      each radio is identified via the RID field) supported by the WTP.
+
+   Radios in Use:   An 8-bit value representing the number of radios
+      present in the WTP.
+
+   Encryption Capabilities:   This 16-bit field is used by the WTP to
+      communicate its capabilities to the AC.  Since most WTPs support
+      link-layer encryption, the AC may make use of these services.
+      There are binding-dependent encryption capabilites.  A WTP that
+      does not have any encryption capabilities would set this field to
+      zero (0).  Refer to the specific binding for the specification.
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 33]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+5.1.3.  WTP Radio Information
+
+   The WTP Radio Information message element is used to communicate the
+   radio information in a specific slot.  The Discovery Request MUST
+   include one such message element per radio in the WTP.  The Radio-
+   Type field is used by the AC in order to determine which technology-
+   specific binding is to be used with the WTP.
+
+   The value contains two fields, as shown:
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Radio ID    |   Radio Type  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   4 for WTP Radio Information
+
+   Length:   2
+
+   Radio ID:   The Radio Identifier, typically refers to some interface
+      index on the WTP.
+
+   Radio Type:   The type of radio present.  The following values are
+      supported:
+
+      1 - 802.11bg:   An 802.11bg radio.
+
+      2 - 802.11a:   An 802.11a radio.
+
+      3 - 802.16:   An 802.16 radio.
+
+      4 - Ultra Wideband:   A UWB radio.
+
+      7 - all:   Used to specify all radios in the WTP.
+
+5.2.  Discovery Response
+
+   The Discovery Response is a mechanism by which an AC advertises its
+   services to requesting WTPs.
+
+   Discovery Responses are sent by an AC after receiving a Discovery
+   Request.
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 34]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   When a WTP receives a Discovery Response, it MUST wait for an
+   interval not less than DiscoveryInterval for receipt of additional
+   Discovery Responses.  After the DiscoveryInterval elapses, the WTP
+   enters the Joining state and will select one of the ACs that sent a
+   Discovery Response and send a Join Request to that AC.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+5.2.1.  AC Address
+
+   The AC Address message element is used to communicate the identity of
+   the AC.  The value contains two fields, as shown:
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Reserved    |                  MAC Address                  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                 MAC Address                   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   2 for AC Address
+
+   Length:   7
+
+   Reserved:   MUST be set to zero
+
+   MAC Address:   The MAC address of the AC
+
+5.2.2.  AC Descriptor
+
+   The AC Descriptor message element is used by the AC to communicate
+   its current state.  The value contains the following fields:
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Reserved    |                 Hardware  Version ...         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     HW Ver    |                 Software  Version ...         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     SW Ver    |            Stations           |     Limit     |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     Limit     |            Radios             |   Max Radio   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Max Radio   |    Security   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+
+
+Calhoun, et al.                 Historic                       [Page 35]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Type:   6 for AC Descriptor
+
+   Length:   17
+
+   Reserved:   MUST be set to zero
+
+   Hardware Version:   A 32-bit integer representing the AC's hardware
+      version number.
+
+   Software Version:   A 32-bit integer representing the AC's Firmware
+      version number.
+
+   Stations:   A 16-bit integer representing the number of mobile
+      stations currently associated with the AC.
+
+   Limit:   A 16-bit integer representing the maximum number of stations
+      supported by the AC.
+
+   Radios:   A 16-bit integer representing the number of WTPs currently
+      attached to the AC.
+
+   Max Radio:   A 16-bit integer representing the maximum number of WTPs
+      supported by the AC.
+
+   Security:   An 8-bit bitmask specifying the security schemes
+      supported by the AC.  The following values are supported (see
+      Section 10):
+
+      1 -  X.509 Certificate-Based
+
+      2 -  Pre-Shared Secret
+
+5.2.3.  AC Name
+
+   The AC Name message element contains an ASCII representation of the
+   AC's identity.  The value is a variable-length byte string.  The
+   string is NOT zero terminated.
+
+       0
+       0 1 2 3 4 5 6 7
+      +-+-+-+-+-+-+-+-+
+      | Name ...
+      +-+-+-+-+-+-+-+-+
+
+   Type:   31 for AC Name
+
+   Length:   > 0
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 36]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Name:   A variable-length ASCII string containing the AC's name.
+
+5.2.4.  WTP Manager Control IPv4 Address
+
+   The WTP Manager Control IPv4 Address message element is sent by the
+   AC to the WTP during the discovery process and is used by the AC to
+   provide the interfaces available on the AC, and their current load.
+   This message element is useful for the WTP to perform load balancing
+   across multiple interfaces.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           IP Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |           WTP Count           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   99 for WTP Manager Control IPv4 Address
+
+   Length:   6
+
+   IP Address:   The IP address of an interface.
+
+   WTP Count:   The number of WTPs currently connected to the interface.
+
+5.2.5.  WTP Manager Control IPv6 Address
+
+   The WTP Manager Control IPv6 Address message element is sent by the
+   AC to the WTP during the discovery process and is used by the AC to
+   provide the interfaces available on the AC, and their current load.
+   This message element is useful for the WTP to perform load balancing
+   across multiple interfaces.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           IP Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           IP Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           IP Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           IP Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |           WTP Count           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 37]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Type:   137 for WTP Manager Control IPv6 Address
+
+   Length:   6
+
+   IP Address:   The IP address of an interface.
+
+   WTP Count:   The number of WTPs currently connected to the interface.
+
+5.3.  Primary Discovery Request
+
+   The Primary Discovery Request is sent by the WTP in order to
+   determine whether its preferred (or primary) AC is available.
+
+   Primary Discovery Requests are sent by a WTP when it has a primary AC
+   configured, and is connected to another AC.  This generally occurs as
+   a result of a failover, and is used by the WTP as a means to discover
+   when its primary AC becomes available.  As a consequence, this
+   message is only sent by a WTP when it is in the Run state.
+
+   The frequency of the Primary Discovery Requests should be no more
+   often than the sending of the Echo Request message.
+
+   Upon receiving a Discovery Request, the AC will respond with a
+   Primary Discovery Response sent to the address in the source address
+   of the received Primary Discovery Request.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+5.3.1.  Discovery Type
+
+   The Discovery Type message element is defined in Section 5.1.1.
+
+5.3.2.  WTP Descriptor
+
+   The WTP Descriptor message element is defined in Section 5.1.2.
+
+5.3.3.  WTP Radio Information
+
+   A WTP Radio Information message element must be present for every
+   radio in the WTP.  This message element is defined in Section 5.1.3.
+
+5.4.  Primary Discovery Response
+
+   The Primary Discovery Response is a mechanism by which an AC
+   advertises its availability and services to requesting WTPs that are
+   configured to have the AC as its primary AC.
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 38]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Primary Discovery Responses are sent by an AC after receiving a
+   Primary Discovery Request.
+
+   When a WTP receives a Primary Discovery Response, it may opt to
+   establish an LWAPP connection to its primary AC, based on the
+   configuration of the WTP Fallback Status message element on the WTP.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+5.4.1.  AC Descriptor
+
+   The Discovery Type message element is defined in Section 5.2.2.
+
+5.4.2.  AC Name
+
+   The AC Name message element is defined in Section 5.2.3.
+
+5.4.3.  WTP Manager Control IPv4 Address
+
+   A WTP Radio Information message element MAY be present for every
+   radio in the WTP that is reachable via IPv4.  This message element is
+   defined in Section 5.2.4.
+
+5.4.4.  WTP Manager Control IPv6 Address
+
+   A WTP Radio Information message element must be present for every
+   radio in the WTP that is reachable via IPv6.  This message element is
+   defined in Section 5.2.5.
+
+6.  Control Channel Management
+
+   The Control Channel Management messages are used by the WTP and AC to
+   create and maintain a channel of communication on which various other
+   commands may be transmitted, such as configuration, firmware update,
+   etc.
+
+6.1.  Join Request
+
+   The Join Request is used by a WTP to inform an AC that it wishes to
+   provide services through it.
+
+   Join Requests are sent by a WTP in the Joining state after receiving
+   one or more Discovery Responses.  The Join Request is also used as an
+   MTU discovery mechanism by the WTP.  The WTP issues a Join Request
+   with a Test message element, bringing the total size of the message
+   to exceed MTU.
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 39]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   If the transport used does not provide MTU path discovery, the
+   initial Join Request is padded with the Test message element to 1596
+   bytes.  If a Join Response is received, the WTP can forward frames
+   without requiring any fragmentation.  If no Join Response is
+   received, it issues a second Join Request padded with the Test
+   payload to a total of 1500 bytes.  The WTP continues to cycle from
+   large (1596) to small (1500) packets until a Join Response has been
+   received, or until both packets' sizes have been retransmitted 3
+   times.  If the Join Response is not received after the maximum number
+   of retransmissions, the WTP MUST abandon the AC and restart the
+   discovery phase.
+
+   When an AC receives a Join Request, it will respond with a Join
+   Response.  If the certificate-based security mechanism is used, the
+   AC validates the certificate found in the request.  If valid, the AC
+   generates a session key that will be used to secure the control
+   frames it exchanges with the WTP.  When the AC issues the Join
+   Response, the AC creates a context for the session with the WTP.
+
+   If the pre-shared session key security mechanism is used, the AC
+   saves the WTP's nonce, found in the WNonce message element, and
+   creates its own nonce, which it includes in the ANonce message
+   element.  Finally, the AC creates the PSK-MIC, which is computed
+   using a key that is derived from the PSK.
+
+   A Join Request that includes both a WNonce and a Certificate message
+   element MUST be considered invalid.
+
+   Details on the key generation are found in Section 10.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+6.1.1.  WTP Descriptor
+
+   The WTP Descriptor message element is defined in Section 5.1.2.
+
+6.1.2.  AC Address
+
+   The AC Address message element is defined in Section 5.2.1.
+
+6.1.3.  WTP Name
+
+   The WTP Name message element value is a variable-length byte string.
+   The string is NOT zero terminated.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 40]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0
+       0 1 2 3 4 5 6 7
+      +-+-+-+-+-+-+-+-+
+      | Name ...
+      +-+-+-+-+-+-+-+-+
+
+   Type:   5 for WTP Name
+
+   Length:   > 0
+
+   Name:   A non-zero-terminated string containing the WTP's name.
+
+6.1.4.  Location Data
+
+   The Location Data message element is a variable-length byte string
+   containing user-defined location information (e.g., "Next to
+   Fridge").  The string is NOT zero terminated.
+
+       0
+       0 1 2 3 4 5 6 7
+      +-+-+-+-+-+-+-+-+
+      | Location ...
+      +-+-+-+-+-+-+-+-+
+
+   Type:   35 for Location Data
+
+   Length:   > 0
+
+   Location:   A non-zero-terminated string containing the WTP's
+      location.
+
+6.1.5.  WTP Radio Information
+
+   A WTP Radio Information message element must be present for every
+   radio in the WTP.  This message element is defined in Section 5.1.3.
+
+6.1.6.  Certificate
+
+   The Certificate message element value is a byte string containing a
+   DER-encoded x.509v3 certificate.  This message element is only
+   included if the LWAPP security type used between the WTP and the AC
+   makes use of certificates (see Section 10 for more information).
+
+       0
+       0 1 2 3 4 5 6 7
+      +-+-+-+-+-+-+-+-+
+      | Certificate...
+      +-+-+-+-+-+-+-+-+
+
+
+
+Calhoun, et al.                 Historic                       [Page 41]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Type:   44 for Certificate
+
+   Length:   > 0
+
+   Certificate:   A non-zero-terminated string containing the device's
+      certificate.
+
+6.1.7.  Session ID
+
+   The Session ID message element value contains a randomly generated
+   [4] unsigned 32-bit integer.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           Session ID                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   45 for Session ID
+
+   Length:   4
+
+   Session ID:   32-bit random session identifier.
+
+6.1.8.  Test
+
+   The Test message element is used as padding to perform MTU discovery,
+   and it MAY contain any value, of any length.
+
+       0
+       0 1 2 3 4 5 6 7
+      +-+-+-+-+-+-+-+-+
+      |  Padding ...
+      +-+-+-+-+-+-+-+-+
+
+   Type:   18 for Test
+
+   Length:   > 0
+
+   Padding:   A variable-length pad.
+
+6.1.9.  XNonce
+
+   The XNonce is used by the WTP to communicate its random nonce during
+   the join or rekey phase.  See Section 10 for more information.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 42]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   111 for XNonce
+
+   Length:   16
+
+   Nonce:   1 16-octet random nonce.
+
+6.2.  Join Response
+
+   The Join Response is sent by the AC to indicate to a WTP whether it
+   is capable and willing to provide service to it.
+
+   Join Responses are sent by the AC after receiving a Join Request.
+   Once the Join Response has been sent, the Heartbeat timer is
+   initiated for the session to EchoInterval.  Expiration of the timer
+   will result in deletion of the AC-WTP session.  The timer is
+   refreshed upon receipt of the Echo Request.
+
+   If the security method used is certificate-based, when a WTP receives
+   a Join Response, it enters the Joined state and initiates either a
+   Configure Request or Image Data to the AC to which it is now joined.
+   Upon entering the Joined state, the WTP begins timing an interval
+   equal to NeighborDeadInterval.  Expiration of the timer will result
+   in the transmission of the Echo Request.
+
+   If the security method used is pre-shared-secret-based, when a WTP
+   receives a Join Response that includes a valid PSK-MIC message
+   element, it responds with a Join ACK that also MUST include a locally
+   computed PSK-MIC message element.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 43]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+6.2.1.  Result Code
+
+   The Result Code message element value is a 32-bit integer value,
+   indicating the result of the request operation corresponding to the
+   sequence number in the message.  The Result Code is included in a
+   successful Join Response.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                         Result Code                           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   2 for Result Code
+
+   Length:   4
+
+   Result Code:   The following values are defined:
+
+      0  Success
+
+      1  Failure (AC List message element MUST be present)
+
+6.2.2.  Status
+
+   The Status message element is sent by the AC to the WTP in a non-
+   successful Join Response message.  This message element is used to
+   indicate the reason for the failure and should only be accompanied
+   with a Result Code message element that indicates a failure.
+
+       0
+       0 1 2 3 4 5 6 7
+      +-+-+-+-+-+-+-+-+
+      |    Status     |
+      +-+-+-+-+-+-+-+-+
+
+   Type:   60 for Status
+
+   Length:   1
+
+   Status:   The Status field indicates the reason for an LWAPP failure.
+      The following values are supported:
+
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 44]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      1 -  Reserved - do not use
+
+      2 -  Resource Depletion
+
+      3 -  Unknown Source
+
+      4 -  Incorrect Data
+
+6.2.3.  Certificate
+
+   The Certificate message element is defined in Section 6.1.6.  Note
+   this message element is only included if the WTP and the AC make use
+   of certificate-based security as defined in Section 10.
+
+6.2.4.  WTP Manager Data IPv4 Address
+
+   The WTP Manager Data IPv4 Address message element is optionally sent
+   by the AC to the WTP during the join phase.  If present, the IP
+   Address contained in this message element is the address the WTP is
+   to use when sending any of its LWAPP data frames.
+
+   Note that this message element is only valid when LWAPP uses the
+   IP/UDP Layer 3 transport.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           IP Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   138 for WTP Manager Data IPv4 Address
+
+   Length:   4
+
+   IP Address:   The IP address of an interface.
+
+6.2.5.  WTP Manager Data IPv6 Address
+
+   The WTP Manager Data IPv6 Address message element is optionally sent
+   by the AC to the WTP during the join phase.  If present, the IP
+   Address contained in this message element is the address the WTP is
+   to use when sending any of its LWAPP data frames.
+
+   Note that this message element is only valid when LWAPP uses the
+   IP/UDP Layer 3 transport.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 45]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           IP Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           IP Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           IP Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           IP Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   139 for WTP Manager Data IPv6 Address
+
+   Length:   4
+
+   IP Address:   The IP address of an interface.
+
+6.2.6.  AC IPv4 List
+
+   The AC List message element is used to configure a WTP with the
+   latest list of ACs in a cluster.  This message element MUST be
+   included if the Join Response returns a failure indicating that the
+   AC cannot handle the WTP at this time, allowing the WTP to find an
+   alternate AC to which to connect.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       AC IP Address[]                         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   59 for AC List
+
+   Length:   >= 4
+
+   AC IP Address:   An array of 32-bit integers containing an AC's IPv4
+      Address.
+
+6.2.7.  AC IPv6 List
+
+   The AC List message element is used to configure a WTP with the
+   latest list of ACs in a cluster.  This message element MUST be
+   included if the Join Response returns a failure indicating that the
+   AC cannot handle the WTP at this time, allowing the WTP to find an
+   alternate AC to which to connect.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 46]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       AC IP Address[]                         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       AC IP Address[]                         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       AC IP Address[]                         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       AC IP Address[]                         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   141 for AC List
+
+   Length:   >= 4
+
+   AC IP Address:   An array of 32-bit integers containing an AC's IPv6
+      Address.
+
+6.2.8.  ANonce
+
+   The ANonce message element is sent by an AC during the join or rekey
+   phase.  The contents of the ANonce are encrypted as described in
+   Section 10 for more information.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   108 for ANonce
+
+   Length:   16
+
+   Nonce:   An encrypted, 16-octet random nonce.
+
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 47]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+6.2.9.  PSK-MIC
+
+   The PSK-MIC message element includes a message integrity check, whose
+   purpose is to provide confirmation to the peer that the sender has
+   the proper session key.  This message element is only included if the
+   security method used between the WTP and the AC is the pre-shared
+   secret mechanism.  See Section 10 for more information.
+
+   When present, the PSK-MIC message element MUST be the last message
+   element in the message.  The MIC is computed over the complete LWAPP
+   packet, from the LWAPP control header as defined in Section 4.2.1 to
+   the end of the packet (which MUST be this PSK-MIC message element).
+   The MIC field in this message element and the Sequence Number field
+   in the LWAPP control header MUST be set to zeroes prior to computing
+   the MIC.  The length field in the LWAPP control header must already
+   include this message element prior to computing the MIC.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |       SPI       |                    MIC ...
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   109 for PSK-MIC
+
+   Length:   > 1
+
+   SPI:   The Security Parameter Index (SPI) field specifies the
+      cryptographic algorithm used to create the message integrity
+      check.  The following values are supported:
+
+      0 -  Unused
+
+      1 -  HMAC-SHA-1 (RFC 2104 [15])
+
+   MIC:   A 20-octet Message Integrity Check.
+
+6.3.  Join ACK
+
+   The Join ACK message is sent by the WTP upon receiving a Join
+   Response, which has a valid PSK-MIC message element, as a means of
+   providing key confirmation to the AC.  The Join ACK is only used in
+   the case where the WTP makes use of the pre-shared key LWAPP mode
+   (see Section 10 for more information).
+
+   Note that the AC should never receive this message unless the
+   security method used between the WTP and the AC is pre-shared-secret-
+   based.
+
+
+
+Calhoun, et al.                 Historic                       [Page 48]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+6.3.1.  Session ID
+
+   The Session ID message element is defined in Section 6.1.7.
+
+6.3.2.  WNonce
+
+   The WNonce message element is sent by a WTP during the join or rekey
+   phase.  The contents of the ANonce are encrypted as described in
+   Section 10 for more information.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Nonce                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   107 for WNonce
+
+   Length:   16
+
+   Nonce:   An encrypted, 16-octet random nonce.
+
+6.3.3.  PSK-MIC
+
+   The PSK-MIC message element is defined in Section 6.2.9.
+
+6.4.  Join Confirm
+
+   The Join Confirm message is sent by the AC upon receiving a Join ACK,
+   which has a valid PSK-MIC message element, as a means of providing
+   key confirmation to the WTP.  The Join Confirm is only used in the
+   case where the WTP makes use of the pre-shared key LWAPP mode (see
+   Section 10 for more information).
+
+   If the security method used is pre-shared-key-based, when a WTP
+   receives a Join Confirm, it enters the Joined state and initiates
+   either a Configure Request or Image Data to the AC to which it is now
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 49]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   joined.  Upon entering the Joined state, the WTP begins timing an
+   interval equal to NeighborDeadInterval.  Expiration of the timer will
+   result in the transmission of the Echo Request.
+
+   This message is never received, or sent, when the security type used
+   between the WTP and the AC is certificated-based.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+6.4.1.  Session ID
+
+   The Session ID message element is defined in Section 6.1.7.
+
+6.4.2.  PSK-MIC
+
+   The PSK-MIC message element is defined in Section 6.2.9.
+
+6.5.  Echo Request
+
+   The Echo Request message is a keepalive mechanism for the LWAPP
+   control message.
+
+   Echo Requests are sent periodically by a WTP in the Run state (see
+   Figure 2) to determine the state of the connection between the WTP
+   and the AC.  The Echo Request is sent by the WTP when the Heartbeat
+   timer expires, and it MUST start its NeighborDeadInterval timer.
+
+   The Echo Request carries no message elements.
+
+   When an AC receives an Echo Request, it responds with an Echo
+   Response.
+
+6.6.  Echo Response
+
+   The Echo Response acknowledges the Echo Request, and is only accepted
+   while in the Run state (see Figure 2).
+
+   Echo Responses are sent by an AC after receiving an Echo Request.
+   After transmitting the Echo Response, the AC should reset its
+   Heartbeat timer to expire in the value configured for EchoInterval.
+   If another Echo request is not received by the AC when the timer
+   expires, the AC SHOULD consider the WTP to no longer be reachable.
+
+   The Echo Response carries no message elements.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 50]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   When a WTP receives an Echo Response it stops the
+   NeighborDeadInterval timer, and starts the Heartbeat timer to
+   EchoInterval.
+
+   If the NeighborDeadInterval timer expires prior to receiving an Echo
+   Response, the WTP enters the Idle state.
+
+6.7.  Key Update Request
+
+   The Key Update Request is used by the WTP to initiate the rekeying
+   phase.  This message is sent by a WTP when in the Run state and MUST
+   include a new unique Session Identifier.  This message MUST also
+   include a unique nonce in the XNonce message element, which is used
+   to protect against replay attacks (see Section 10).
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+6.7.1.  Session ID
+
+   The Session ID message element is defined in Section 6.1.7.
+
+6.7.2.  XNonce
+
+   The XNonce message element is defined in Section 6.1.9.
+
+6.8.  Key Update Response
+
+   The Key Update Response is sent by the AC in response to the request
+   message, and includes an encrypted ANonce, which is used to derive
+   new session keys.  This message MUST include a Session Identifier
+   message element, whose value MUST be identical to the one found in
+   the Key Update Request.
+
+   The AC MUST include a PSK-MIC message element, which provides message
+   integrity over the whole message.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+6.8.1.  Session ID
+
+   The Session ID message element is defined in Section 6.1.7.
+
+6.8.2.  ANonce
+
+   The ANonce message element is defined in Section 6.2.8.
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 51]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+6.8.3.  PSK-MIC
+
+   The PSK-MIC message element is defined in Section 6.2.9.
+
+6.9.  Key Update ACK
+
+   The Key Update ACK is sent by the WTP and includes an encrypted
+   version of the WTP's nonce, which is used in the key derivation
+   process.  The session keys derived are then used as new LWAPP control
+   message encryption keys (see Section 10).
+
+   The WTP MUST include a PSK-MIC message element, which provides
+   message integrity over the whole message.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+6.9.1.  WNonce
+
+   The WNonce message element is defined in Section 6.3.2.
+
+6.9.2.  PSK-MIC
+
+   The PSK-MIC message element is defined in Section 6.2.9.
+
+6.10.  Key Update Confirm
+
+   The Key Update Confirm closes the rekeying loop, and allows the WTP
+   to recognize that the AC has received and processed the Key Update
+   messages.  At this point, the WTP updates its session key in its
+   crypto engine, and the associated Initialization Vector, ensuring
+   that all future LWAPP control frames are encrypted with the newly
+   derived encryption key.
+
+   The WTP MUST include a PSK-MIC message element, which provides
+   message integrity over the whole message.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+6.10.1.  PSK-MIC
+
+   The PSK-MIC message element is defined in Section 6.2.9.
+
+6.11.  Key Update Trigger
+
+   The Key Update Trigger is used by the AC to request that a Key Update
+   Request be initiated by the WTP.
+
+
+
+Calhoun, et al.                 Historic                       [Page 52]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Key Update Triggers are sent by an AC in the Run state to inform the
+   WTP to initiate a Key Update Request message.
+
+   When a WTP receives a Key Update Trigger, it generates a Key Update
+   Request.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+6.11.1.  Session ID
+
+   The Session ID message element is defined in Section 6.1.7.
+
+7.  WTP Configuration Management
+
+   The Wireless Termination Point Configuration messages are used to
+   exchange configuration between the AC and the WTP.
+
+7.1.  Configuration Consistency
+
+   The LWAPP protocol provides flexibility in how WTP configuration is
+   managed.  To put it simply, a WTP has one of two options:
+
+   1. The WTP retains no configuration and simply abides by the
+      configuration provided by the AC.
+
+   2. The WTP retains the configuration of parameters provided by the AC
+      that are non-default values.
+
+   If the WTP opts to save configuration locally, the LWAPP protocol
+   state machine defines the "Configure" state, which is used during the
+   initial binding WTP-AC phase, which allows for configuration
+   exchange.  During this period, the WTP sends its current
+   configuration overrides to the AC via the Configure Request message.
+   A configuration override is a parameter that is non-default.  One
+   example is that in the LWAPP protocol, the default antenna
+   configuration is an internal-omni antenna.  However, a WTP that
+   either has no internal antennas, or has been explicitely configured
+   by the AC to use external antennas would send its antenna
+   configuration during the configure phase, allowing the AC to become
+   aware of the WTP's current configuration.
+
+   Once the WTP has provided its configuration to the AC, the AC sends
+   down its own configuration.  This allows the WTP to inherit the
+   configuration and policies on the AC.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 53]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   An LWAPP AC maintains a copy of each active WTP's configuration.
+   There is no need for versioning or other means to identify
+   configuration changes.  If a WTP becomes inactive, the AC MAY delete
+   the configuration associated with it.  If a WTP were to fail, and
+   connect to a new AC, it would provide its overridden configuration
+   parameters, allowing the new AC to be aware of the WTP's
+   configuration.
+
+   As a consequence, this model allows for resiliency, whereby in light
+   of an AC failure, another AC could provide service to the WTP.  In
+   this scenario, the new AC would be automatically updated on any
+   possible WTP configuration changes -- eliminating the need for Inter-
+   AC communication or the need for all ACs to be aware of the
+   configuration of all WTPs in the network.
+
+   Once the LWAPP protocol enters the Run state, the WTPs begin to
+   provide service.  However, it is quite common for administrators to
+   require that configuration changes be made while the network is
+   operational.  Therefore, the Configuration Update Request is sent by
+   the AC to the WTP in order to make these changes at run-time.
+
+7.2.  Configure Request
+
+   The Configure Request message is sent by a WTP to send its current
+   configuration to its AC.
+
+   Configure Requests are sent by a WTP after receiving a Join Response,
+   while in the Configure state.
+
+   The Configure Request carries binding-specific message elements.
+   Refer to the appropriate binding for the definition of this
+   structure.
+
+   When an AC receives a Configure Request, it will act upon the content
+   of the packet and respond to the WTP with a Configure Response.
+
+   The Configure Request includes multiple Administrative State message
+   elements.  There is one such message element for the WTP, and then
+   one per radio in the WTP.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+7.2.1.  Administrative State
+
+   The Administrative Event message element is used to communicate the
+   state of a particular radio.  The value contains the following
+   fields.
+
+
+
+Calhoun, et al.                 Historic                       [Page 54]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |  Admin State  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   27 for Administrative State
+
+   Length:   2
+
+   Radio ID:   An 8-bit value representing the radio to configure.  The
+      Radio ID field may also include the value of 0xff, which is used
+      to identify the WTP itself.  Therefore, if an AC wishes to change
+      the administrative state of a WTP, it would include 0xff in the
+      Radio ID field.
+
+   Admin State:   An 8-bit value representing the administrative state
+      of the radio.  The following values are supported:
+
+      1 -  Enabled
+
+      2 -  Disabled
+
+7.2.2.  AC Name
+
+   The AC Name message element is defined in Section 5.2.3.
+
+7.2.3.  AC Name with Index
+
+   The AC Name with Index message element is sent by the AC to the WTP
+   to configure preferred ACs.  The number of instances where this
+   message element would be present is equal to the number of ACs
+   configured on the WTP.
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     Index     |   AC Name...
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   90 for AC Name with Index
+
+   Length:   5
+
+   Index:   The index of the preferred server (e.g., 1=primary,
+      2=secondary).
+
+   AC Name:   A variable-length ASCII string containing the AC's name.
+
+
+
+Calhoun, et al.                 Historic                       [Page 55]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+7.2.4.  WTP Board Data
+
+   The WTP Board Data message element is sent by the WTP to the AC and
+   contains information about the hardware present.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |            Card ID            |         Card Revision         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          WTP Model                            |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          WTP Model                            |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                      WTP Serial Number ...                    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           Reserved                            |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                     Ethernet MAC Address                      |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      Ethernet MAC Address     |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   50 for WTP Board Data
+
+   Length:   26
+
+   Card ID:   A hardware identifier.
+
+   Card Revision:   4-byte Revision of the card.
+
+   WTP Model:   8-byte WTP Model Number.
+
+   WTP Serial Number:   24-byte WTP Serial Number.
+
+   Reserved:   A 4-byte reserved field that MUST be set to zero (0).
+
+   Ethernet MAC Address:   MAC address of the WTP's Ethernet interface.
+
+7.2.5.  Statistics Timer
+
+   The Statistics Timer message element value is used by the AC to
+   inform the WTP of the frequency that it expects to receive updated
+   statistics.
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 56]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |        Statistics Timer       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   37 for Statistics Timer
+
+   Length:   2
+
+   Statistics Timer:   A 16-bit unsigned integer indicating the time, in
+      seconds.
+
+7.2.6.  WTP Static IP Address Information
+
+   The WTP Static IP Address Information message element is used by an
+   AC to configure or clear a previously configured static IP address on
+   a WTP.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          IP Address                           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                            Netmask                            |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                            Gateway                            |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Static     |
+      +-+-+-+-+-+-+-+-+
+
+   Type:   82 for WTP Static IP Address Information
+
+   Length:   13
+
+   IP Address:   The IP address to assign to the WTP.
+
+   Netmask:   The IP Netmask.
+
+   Gateway:   The IP address of the gateway.
+
+   Netmask:   The IP Netmask.
+
+   Static:   An 8-bit Boolean stating whether or not the WTP should use
+      a static IP address.  A value of zero disables the static IP
+      address, while a value of one enables it.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 57]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+7.2.7.  WTP Reboot Statistics
+
+   The WTP Reboot Statistics message element is sent by the WTP to the
+   AC to communicate information about reasons why reboots have
+   occurred.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |          Crash Count          |     LWAPP Initiated Count     |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      Link Failure Count       | Failure Type  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   67 for WTP Reboot Statistics
+
+   Length:   7
+
+   Crash Count:   The number of reboots that have occurred due to a WTP
+      crash.
+
+   LWAPP Initiated Count:   The number of reboots that have occurred at
+      the request of some LWAPP message, such as a change in
+      configuration that required a reboot or an explicit LWAPP reset
+      request.
+
+   Link Failure Count:   The number of times that an LWAPP connection
+      with an AC has failed.
+
+   Failure Type:   The last WTP failure.  The following values are
+      supported:
+
+      0 -  Link Failure
+
+      1 -  LWAPP Initiated
+
+      2 -  WTP Crash
+
+7.3.  Configure Response
+
+   The Configure Response message is sent by an AC and provides an
+   opportunity for the AC to override a WTP's requested configuration.
+
+   Configure Responses are sent by an AC after receiving a Configure
+   Request.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 58]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   The Configure Response carries binding-specific message elements.
+   Refer to the appropriate binding for the definition of this
+   structure.
+
+   When a WTP receives a Configure Response, it acts upon the content of
+   the packet, as appropriate.  If the Configure Response message
+   includes a Change State Event message element that causes a change in
+   the operational state of one of the Radios, the WTP will transmit a
+   Change State Event to the AC as an acknowledgement of the change in
+   state.
+
+   The following subsections define the message elements that MUST be
+   included in this LWAPP operation.
+
+7.3.1.  Decryption Error Report Period
+
+   The Decryption Error Report Period message element value is used by
+   the AC to inform the WTP of how frequently it should send decryption
+   error report messages.
+
+       0                   1                   2
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Radio ID    |        Report Interval        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   38 for Decryption Error Report Period
+
+   Length:   3
+
+   Radio ID:   The Radio Identifier: typically refers to some interface
+      index on the WTP.
+
+   Report Interval:   A 16-bit, unsigned integer indicating the time, in
+      seconds.
+
+7.3.2.  Change State Event
+
+   The WTP Radio Information message element is used to communicate the
+   operational state of a radio.  The value contains two fields, as
+   shown.
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Radio ID    |     State     |     Cause     |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 59]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Type:   26 for Change State Event
+
+   Length:   3
+
+   Radio ID:   The Radio Identifier: typically refers to some interface
+      index on the WTP.
+
+   State:   An 8-bit Boolean value representing the state of the radio.
+      A value of one disables the radio, while a value of two enables
+      it.
+
+   Cause:   In the event of a radio being inoperable, the Cause field
+      would contain the reason the radio is out of service.  The
+      following values are supported:
+
+      0 -  Normal
+
+      1 -  Radio Failure
+
+      2 -  Software Failure
+
+7.3.3.  LWAPP Timers
+
+   The LWAPP Timers message element is used by an AC to configure LWAPP
+   timers on a WTP.
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Discovery   | Echo Request  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   68 for LWAPP Timers
+
+   Length:   2
+
+   Discovery:   The number of seconds between LWAPP Discovery packets
+      when the WTP is in the discovery mode.
+
+   Echo Request:   The number of seconds between WTP Echo Request LWAPP
+      messages.
+
+7.3.4.  AC IPv4 List
+
+   The AC List message element is defined in Section 6.2.6.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 60]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+7.3.5.  AC IPv6 List
+
+   The AC List message element is defined in Section 6.2.7.
+
+7.3.6.  WTP Fallback
+
+   The WTP Fallback message element is sent by the AC to the WTP to
+   enable or disable automatic LWAPP fallback in the event that a WTP
+   detects its preferred AC, and is not currently connected to it.
+
+       0
+       0 1 2 3 4 5 6 7
+      +-+-+-+-+-+-+-+-+
+      |     Mode      |
+      +-+-+-+-+-+-+-+-+
+
+   Type:   91 for WTP Fallback
+
+   Length:   1
+
+   Mode:   The 8-bit Boolean value indicates the status of automatic
+      LWAPP fallback on the WTP.  A value of zero disables the fallback
+      feature, while a value of one enables it.  When enabled, if the
+      WTP detects that its primary AC is available, and it is not
+      connected to it, it SHOULD automatically disconnect from its
+      current AC and reconnect to its primary.  If disabled, the WTP
+      will only reconnect to its primary through manual intervention
+      (e.g., through the Reset Request command).
+
+7.3.7.  Idle Timeout
+
+   The Idle Timeout message element is sent by the AC to the WTP to
+   provide it with the idle timeout that it should enforce on its active
+   mobile station entries.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                            Timeout                            |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   97 for Idle Timeout
+
+   Length:   4
+
+   Timeout:   The current idle timeout to be enforced by the WTP.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 61]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+7.4.  Configuration Update Request
+
+   Configure Update Requests are sent by the AC to provision the WTP
+   while in the Run state.  This is used to modify the configuration of
+   the WTP while it is operational.
+
+   When an AC receives a Configuration Update Request it will respond
+   with a Configuration Update Response, with the appropriate Result
+   Code.
+
+   The following subsections define the message elements introduced by
+   this LWAPP operation.
+
+7.4.1.  WTP Name
+
+   The WTP Name message element is defined in Section 6.1.3.
+
+7.4.2.  Change State Event
+
+   The Change State Event message element is defined in Section 7.3.2.
+
+7.4.3.  Administrative State
+
+   The Administrative State message element is defined in Section 7.2.1.
+
+7.4.4.  Statistics Timer
+
+   The Statistics Timer message element is defined in Section 7.2.5.
+
+7.4.5.  Location Data
+
+   The Location Data message element is defined in Section 6.1.4.
+
+7.4.6.  Decryption Error Report Period
+
+   The Decryption Error Report Period message element is defined in
+   Section 7.3.1.
+
+7.4.7.  AC IPv4 List
+
+   The AC List message element is defined in Section 6.2.6.
+
+7.4.8.  AC IPv6 List
+
+   The AC List message element is defined in Section 6.2.7.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 62]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+7.4.9.  Add Blacklist Entry
+
+   The Add Blacklist Entry message element is used by an AC to add a
+   blacklist entry on a WTP, ensuring that the WTP no longer provides
+   any service to the MAC addresses provided in the message.  The MAC
+   addresses provided in this message element are not expected to be
+   saved in non-volative memory on the WTP.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | Num of Entries|                 MAC Address[]                 |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                 MAC Address[]                 |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   65 for Add Blacklist Entry
+
+   Length:   >= 7
+
+   Num of Entries:   The number of MAC addresses in the array.
+
+   MAC Address:   An array of MAC addresses to add to the blacklist
+      entry.
+
+7.4.10.  Delete Blacklist Entry
+
+   The Delete Blacklist Entry message element is used by an AC to delete
+   a previously added blacklist entry on a WTP, ensuring that the WTP
+   provides service to the MAC addresses provided in the message.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | Num of Entries|                 MAC Address[]                 |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                 MAC Address[]                 |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   66 for Delete Blacklist Entry
+
+   Length:   >= 7
+
+   Num of Entries:   The number of MAC addresses in the array.
+
+   MAC Address:   An array of MAC addresses to delete from the blacklist
+      entry.
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 63]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+7.4.11.  Add Static Blacklist Entry
+
+   The Add Static Blacklist Entry message element is used by an AC to
+   add a permanent Blacklist Entry on a WTP, ensuring that the WTP no
+   longer provides any service to the MAC addresses provided in the
+   message.  The MAC addresses provided in this message element are
+   expected to be saved in non-volative memory on the WTP.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | Num of Entries|                 MAC Address[]                 |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                 MAC Address[]                 |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   70 for Delete Blacklist Entry
+
+   Length:   >= 7
+
+   Num of Entries:   The number of MAC addresses in the array.
+
+   MAC Address:   An array of MAC addresses to add to the permanent
+      blacklist entry.
+
+7.4.12.  Delete Static Blacklist Entry
+
+   The Delete Static Blacklist Entry message element is used by an AC to
+   delete a previously added static blacklist entry on a WTP, ensuring
+   that the WTP provides service to the MAC addresses provided in the
+   message.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | Num of Entries|                 MAC Address[]                 |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                 MAC Address[]                 |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   71 for Delete Blacklist Entry
+
+   Length:   >= 7
+
+   Num of Entries:   The number of MAC addresses in the array.
+
+   MAC Address:   An array of MAC addresses to delete from the static
+      blacklist entry.
+
+
+
+Calhoun, et al.                 Historic                       [Page 64]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+7.4.13.  LWAPP Timers
+
+   The LWAPP Timers message element is defined in Section 7.3.3.
+
+7.4.14.  AC Name with Index
+
+   The AC Name with Index message element is defined in Section 7.2.3.
+
+7.4.15.  WTP Fallback
+
+   The WTP Fallback message element is defined in Section 7.3.6.
+
+7.4.16.  Idle Timeout
+
+   The Idle Timeout message element is defined in Section 7.3.7.
+
+7.5.  Configuration Update Response
+
+   The Configuration Update Response is the acknowledgement message for
+   the Configuration Update Request.
+
+   Configuration Update Responses are sent by a WTP after receiving a
+   Configuration Update Request.
+
+   When an AC receives a Configure Update Response, the result code
+   indicates if the WTP successfully accepted the configuration.
+
+   The following subsections define the message elements that must be
+   present in this LWAPP operation.
+
+7.5.1.  Result Code
+
+   The Result Code message element is defined in Section 6.2.1.
+
+7.6.  Change State Event Request
+
+   The Change State Event is used by the WTP to inform the AC of a
+   change in the operational state.
+
+   The Change State Event message is sent by the WTP when it receives a
+   Configuration Response that includes a Change State Event message
+   element.  It is also sent in the event that the WTP detects an
+   operational failure with a radio.  The Change State Event may be sent
+   in either the Configure or Run state (see Figure 2).
+
+   When an AC receives a Change State Event it will respond with a
+   Change State Event Response and make any necessary modifications to
+   internal WTP data structures.
+
+
+
+Calhoun, et al.                 Historic                       [Page 65]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   The following subsections define the message elements that must be
+   present in this LWAPP operation.
+
+7.6.1.  Change State Event
+
+   The Change State Event message element is defined in Section 7.3.2.
+
+7.7.  Change State Event Response
+
+   The Change State Event Response acknowledges the Change State Event.
+
+   Change State Event Responses are sent by a WTP after receiving a
+   Change State Event.
+
+   The Change State Event Response carries no message elements.  Its
+   purpose is to acknowledge the receipt of the Change State Event.
+
+   The WTP does not need to perform any special processing of the Change
+   State Event Response message.
+
+7.8.  Clear Config Indication
+
+   The Clear Config Indication is used to reset a WTP's configuration.
+
+   The Clear Config Indication is sent by an AC to request that a WTP
+   reset its configuration to manufacturing defaults.  The Clear Config
+   Indication message is sent while in the Run LWAPP state.
+
+   The Reset Request carries no message elements.
+
+   When a WTP receives a Clear Config Indication, it will reset its
+   configuration to manufacturing defaults.
+
+8.  Device Management Operations
+
+   This section defines LWAPP operations responsible for debugging,
+   gathering statistics, logging, and firmware management.
+
+8.1.  Image Data Request
+
+   The Image Data Request is used to update firmware on the WTP.  This
+   message and its companion response are used by the AC to ensure that
+   the image being run on each WTP is appropriate.
+
+   Image Data Requests are exchanged between the WTP and the AC to
+   download a new program image to a WTP.
+
+   When a WTP or AC receives an Image Data Request, it will respond with
+
+
+
+Calhoun, et al.                 Historic                       [Page 66]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   an Image Data Response.
+
+   The format of the Image Data and Image Download message elements are
+   described in the following subsections.
+
+8.1.1.  Image Download
+
+   The Image Download message element is sent by the WTP to the AC and
+   contains the image filename.  The value is a variable-length byte
+   string.  The string is NOT zero terminated.
+
+8.1.2.  Image Data
+
+   The Image Data message element is present when sent by the AC and
+   contains the following fields.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     Opcode    |           Checksum            |  Image Data   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          Image Data ...                       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   33 for Image Data
+
+   Length:   >= 5
+
+   Opcode:   An 8-bit value representing the transfer opcode.  The
+      following values are supported:
+
+      3 -  Image Data is included.
+
+      5 -  An error occurred.  Transfer is aborted.
+
+   Checksum:   A 16-bit value containing a checksum of the Image Data
+      that follows.
+
+   Image Data:   The Image Data field contains 1024 characters, unless
+      the payload being sent is the last one (end of file).
+
+
+
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 67]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+8.2.  Image Data Response
+
+   The Image Data Response acknowledges the Image Data Request.
+
+   An Image Data Responses is sent in response to an Image Data Request.
+   Its purpose is to acknowledge the receipt of the Image Data Request
+   packet.
+
+   The Image Data Response carries no message elements.
+
+   No action is necessary on receipt.
+
+8.3.  Reset Request
+
+   The Reset Request is used to cause a WTP to reboot.
+
+   Reset Requests are sent by an AC to cause a WTP to reinitialize its
+   operation.
+
+   The Reset Request carries no message elements.
+
+   When a WTP receives a Reset Request it will respond with a Reset
+   Response and then reinitialize itself.
+
+8.4.  Reset Response
+
+   The Reset Response acknowledges the Reset Request.
+
+   Reset Responses are sent by a WTP after receiving a Reset Request.
+
+   The Reset Response carries no message elements.  Its purpose is to
+   acknowledge the receipt of the Reset Request.
+
+   When an AC receives a Reset Response, it is notified that the WTP
+   will now reinitialize its operation.
+
+8.5.  WTP Event Request
+
+   The WTP Event Request is used by a WTP to send information to its AC.
+   These types of events may be periodical, or some asynchronous event
+   on the WTP.  For instance, a WTP collects statistics and uses the WTP
+   Event Request to transmit this information to the AC.
+
+   When an AC receives a WTP Event Request, it will respond with a WTP
+   Event Request.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 68]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   The WTP Event Request message MUST contain one of the following
+   message element described in the next subsections, or a message
+   element that is defined for a specific technology.
+
+8.5.1.  Decryption Error Report
+
+   The Decryption Error Report message element value is used by the WTP
+   to inform the AC of decryption errors that have occurred since the
+   last report.
+
+       0                   1                   2
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Radio ID    |Num Of Entries |      Mobile MAC Address       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       Mobile MAC Address[]                    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   39 for Decryption Error Report
+
+   Length:   >= 8
+
+   Radio ID:   The Radio Identifier, typically refers to some interface
+      index on the WTP.
+
+   Num Of Entries:   An 8-bit unsigned integer indicating the number of
+      mobile MAC addresses.
+
+   Mobile MAC Address:   An array of mobile station MAC addresses that
+      have caused decryption errors.
+
+8.5.2.  Duplicate IPv4 Address
+
+   The Duplicate IPv4 Address message element is used by a WTP to inform
+   an AC that it has detected another host using the same IP address it
+   is currently using.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          IP Address                           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          MAC Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |          MAC Address          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   77 for Duplicate IPv4 Address
+
+
+
+Calhoun, et al.                 Historic                       [Page 69]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Length:   10
+
+   IP Address:   The IP address currently used by the WTP.
+
+   MAC Address:   The MAC address of the offending device.
+
+8.5.3.  Duplicate IPv6 Address
+
+   The Duplicate IPv6 Address message element is used by a WTP to inform
+   an AC that it has detected another host using the same IP address it
+   is currently using.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          IP Address                           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          IP Address                           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          IP Address                           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          IP Address                           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          MAC Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |          MAC Address          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   77 for Duplicate IPv6 Address
+
+   Length:   10
+
+   IP Address:   The IP address currently used by the WTP.
+
+   MAC Address:   The MAC address of the offending device.
+
+8.6.  WTP Event Response
+
+   The WTP Event Response acknowledges the WTP Event Request.
+
+   WTP Event Responses are sent by an AC after receiving a WTP Event
+   Request.
+
+   The WTP Event Response carries no message elements.
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 70]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+8.7.  Data Transfer Request
+
+   The Data Transfer Request is used to upload debug information from
+   the WTP to the AC.
+
+   Data Transfer Requests are sent by the WTP to the AC when it
+   determines that it has important information to send to the AC.  For
+   instance, if the WTP detects that its previous reboot was caused by a
+   system crash, it would want to send the crash file to the AC.  The
+   remote debugger function in the WTP also uses the Data Transfer
+   Request in order to send console output to the AC for debugging
+   purposes.
+
+   When an AC receives a Data Transfer Request, it will respond with a
+   Data Transfer Response.  The AC may log the information received as
+   it sees fit.
+
+   The Data Transfer Request message MUST contain ONE of the following
+   message element described in the next subsection.
+
+8.7.1.  Data Transfer Mode
+
+   The Data Transfer Mode message element is used by the AC to request
+   information from the WTP for debugging purposes.
+
+       0
+       0 1 2 3 4 5 6 7
+      +-+-+-+-+-+-+-+-+
+      |   Data  Type   |
+      +-+-+-+-+-+-+-+-+
+
+   Type:   52 for Data Transfer Mode
+
+   Length:   1
+
+   Data Type:   An 8-bit value describing the type of information being
+      requested.  The following values are supported:
+
+      1 -  WTP Crash Data
+
+      2 -  WTP Memory Dump
+
+8.7.2.  Data Transfer Data
+
+   The Data Transfer Data message element is used by the WTP to provide
+   information to the AC for debugging purposes.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 71]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Data Type   |  Data Length  |    Data ....
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   53 for Data Transfer Data
+
+   Length:   >= 3
+
+   Data Type:   An 8-bit value describing the type of information being
+      sent.  The following values are supported:
+
+      1 -  WTP Crash Data
+
+      2 -  WTP Memory Dump
+
+   Data Length:   Length of data field.
+
+   Data:   Debug information.
+
+8.8.  Data Transfer Response
+
+   The Data Transfer Response acknowledges the Data Transfer Request.
+
+   A Data Transfer Response is sent in response to a Data Transfer
+   Request.  Its purpose is to acknowledge the receipt of the Data
+   Transfer Request packet.
+
+   The Data Transfer Response carries no message elements.
+
+   Upon receipt of a Data Transfer Response, the WTP transmits more
+   information, if any is available.
+
+9.  Mobile Session Management
+
+   Messages in this section are used by the AC to create, modify, or
+   delete mobile station session state on the WTPs.
+
+9.1.  Mobile Config Request
+
+   The Mobile Config Request message is used to create, modify, or
+   delete mobile session state on a WTP.  The message is sent by the AC
+   to the WTP, and may contain one or more message elements.  The
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 72]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   message elements for this LWAPP control message include information
+   that is generally highly technology-specific.  Therefore, please
+   refer to the appropriate binding section or document for the
+   definitions of the messages elements that may be used in this control
+   message.
+
+   This section defines the format of the Delete Mobile message element,
+   since it does not contain any technology-specific information.
+
+9.1.1.  Delete Mobile
+
+   The Delete Mobile message element is used by the AC to inform a WTP
+   that it should no longer provide service to a particular mobile
+   station.  The WTP must terminate service immediately upon receiving
+   this message element.
+
+   The transmission of a Delete Mobile message element could occur for
+   various reasons, including administrative reasons, as a result of the
+   fact that the mobile has roamed to another WTP, etc.
+
+   Once access has been terminated for a given station, any future
+   packets received from the mobile must result in a deauthenticate
+   message, as specified in [6].
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |                  MAC Address                  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                  MAC Address                  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   30 for Delete Mobile
+
+   Length:   7
+
+   Radio ID:   An 8-bit value representing the radio
+
+   MAC Address:   The mobile station's MAC address
+
+9.2.  Mobile Config Response
+
+   The Mobile Configuration Response is used to acknowledge a previously
+   received Mobile Configuration Request, and includes a Result Code
+   message element that indicates whether an error occurred on the WTP.
+
+   This message requires no special processing and is only used to
+   acknowledge the Mobile Configuration Request.
+
+
+
+Calhoun, et al.                 Historic                       [Page 73]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   The Data Transfer Request message MUST contain the message elements
+   described in the next subsection.
+
+9.2.1.  Result Code
+
+   The Result Code message element is defined in Section 6.2.1.
+
+10.  LWAPP Security
+
+   Note: This version only defines a certificate and a shared-secret-
+   based mechanism to secure control LWAPP traffic exchanged between the
+   WTP and the AC.
+
+10.1.  Securing WTP-AC Communications
+
+   While it is generally straightforward to produce network
+   installations in which the communications medium between the WTP and
+   AC is not accessible to the casual user (e.g., these LAN segments are
+   isolated, and no RJ45 or other access ports exist between the WTP and
+   the AC), this will not always be the case.  Furthermore, a determined
+   attacker may resort to various, more sophisticated monitoring and/or
+   access techniques, thereby compromising the integrity of this
+   connection.
+
+   In general, a certain level of threat on the local (wired) LAN is
+   expected and accepted in most computing environments.  That is, it is
+   expected that in order to provide users with an acceptable level of
+   service and maintain reasonable productivity levels, a certain amount
+   of risk must be tolerated.  It is generally believed that a certain
+   perimeter is maintained around such LANs, that an attacker must have
+   access to the building(s) in which such LANs exist, and that they
+   must be able to "plug in" to the LAN in order to access the network.
+
+   With these things in mind, we can begin to assess the general
+   security requirements for AC-WTP communications.  While an in-depth
+   security analysis of threats and risks to these communications is
+   beyond the scope of this document, some discussion of the motivation
+   for various security-related design choices is useful.  The
+   assumptions driving the security design thus far include the
+   following:
+
+   o  WTP-AC communications take place over a wired connection that may
+      be accessible to a sophisticated attacker.
+
+   o  access to this connection is not trivial for an outsider (i.e.,
+      someone who does not "belong" in the building) to access.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 74]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   o  if authentication and/or privacy of end-to-end traffic for which
+      the WTP and AC are intermediaries is required, this may be
+      provided via IPsec [14].
+
+   o  privacy and authentication for at least some WTP-AC control
+      traffic is required (e.g., Wired Equivalent Privacy (WEP) keys for
+      user sessions, passed from the AC to the WTP).
+
+   o  the AC can be trusted to generate strong cryptographic keys.
+
+   The AC-WTP traffic can be considered to consist of two types: data
+   traffic (e.g., to or from an end user), and control traffic, which is
+   strictly between the AC and WTP.  Since data traffic may be secured
+   using IPsec (or some other end-to-end security mechanism), we confine
+   our solution to control traffic.  The resulting security consists of
+   two components: an authenticated key exchange and control traffic
+   security encapsulation.  The security encapsulation is accomplished
+   using AES-CCM, described in [3].  This encapsulation provides for
+   strong AES-based authentication and encryption [2].  The exchange of
+   cryptographic keys used for CCM is described below.
+
+10.2.  LWAPP Frame Encryption
+
+   While the LWAPP protocol uses AES-CCM to encrypt control traffic, it
+   is important to note that not all control frames are encrypted.  The
+   LWAPP discovery and join phase are not encrypted.  The Discovery
+   messages are sent in the clear since there does not exist a security
+   association between the WTP and the AC during the discovery phase.
+   The join phase is an authenticated exchange used to negotiate
+   symmetric session keys (see Section 10.3).
+
+   Once the join phase has been successfully completed, the LWAPP state
+   machine Figure 2 will move to the Configure state, at which time all
+   LWAPP control frames are encrypted using AES-CCM.
+
+   Encryption of a control message begins at the Message Element field:
+   meaning the Msg Type, Seq Num, Msg Element Length, and Session ID
+   fields are left intact (see Section 4.2.1).
+
+   The AES-CCM 12-byte authentication data is appended to the end of the
+   message.  The authentication data is calculated from the start of the
+   LWAPP packet and includes the complete LWAPP control header (see
+   Section 4.2.1).
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 75]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   The AES-CCM block cipher protocol requires an initialization vector.
+   The LWAPP protocol requires that the WTP and the AC maintain two
+   separate IVs, one for transmission and one for reception.  The IV
+   derived during the key exchange phase by both the WTP and the AC is
+   used as the base for all encrypted packets with a new key.
+
+10.3.  Authenticated Key Exchange
+
+   This section describes the key management component of the LWAPP
+   protocol.  There are two modes supported by LWAPP: certificate and
+   pre-shared key.
+
+10.3.1.  Terminology
+
+   This section details the key management protocol that makes use of
+   pre-shared secrets.
+
+   The following notations are used throughout this section:
+
+   o  PSK - the pre-shared key shared between the WTP and the AC.
+
+   o  Kpriv - the private key of a public-private key pair.
+
+   o  Kpub - the public key of the pair.
+
+   o  SessionID - a randomly generated LWAPP session identifier,
+      provided by the WTP in the Join Request.
+
+   o  E-x{Kpub, M} - RSA encryption of M using X's public key.
+
+   o  D-x{Kpriv, C} - RSA decryption of C using X's private key.
+
+   o  AES-CMAC(key, packet) - A message integrity check, using AES-CMAC
+      and key, of the complete LWAPP packet, with the Sequence Number
+      field and the payload of the PSK-MIC message element set to zero.
+
+   o  AES-E(key, plaintext) - Plaintext is encrypted with key, using
+      AES.
+
+   o  AES-D(key, ciphertext) - ciphertext is decrypted with key, using
+      AES.
+
+   o  Certificate-AC - AC's Certificate.
+
+   o  Certificate-WTP - WTP's Certificate.
+
+   o  WTP-MAC - The WTP's MAC address.
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 76]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   o  AC-MAC - The AC's MAC address.
+
+   o  RK0 - the root key, which is created through a Key Derivation
+      Function (KDF) function.
+
+   o  RK0E - the root Encryption key, derived from RK0.
+
+   o  RK0M - the root MIC key, derived from RK0.
+
+   o  SK1 - the session key.
+
+   o  SK1C - the session confirmation key, derived from SK.
+
+   o  SK1E - the session encryption key, derived from SK.
+
+   o  SK1W - the session keywrap key, derived from SK (see RFC 3394
+      [9]).
+
+   o  WNonce - The WTP's randomly generated nonce.
+
+   o  ANonce - The AC's randomly generated nonce.
+
+   o  EWNonce - The payload of the WNonce message element, which
+      includes the WNonce.
+
+   o  EANonce - The payload of the ANonce message element, which
+      includes the ANonce.
+
+10.3.2.  Initial Key Generation
+
+   The AC and WTP accomplish mutual authentication and a cryptographic
+   key exchange in a dual round trip using the Join Request, Join
+   Response, Join ACK, and Join Confirm (see Section 6.1).
+
+   The following text describes the exchange between the WTP and the AC
+   that creates a session key, which is used to secure LWAPP control
+   messages.
+
+   o  The WTP creates a Join Request using the following process:
+
+      o  If certificate-based security is used, the WTP adds the
+         Certificate message element (see Section 6.1.6) with its
+         contents set to Certificate-WTP.
+
+      o  The WTP adds the Session ID message element (see Section 6.1.7)
+         with the contents set to a randomly generated session
+         identifier (see RFC 1750 [4]).  The WTP MUST save the Session
+         ID in order to validate the Join Response.
+
+
+
+Calhoun, et al.                 Historic                       [Page 77]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      o  The WTP creates a random nonce, included in the XNonce message
+         element (see Section 6.1.9).  The WTP MUST save the XNonce to
+         validate the Join Response.
+
+      o  The WTP transmits the Join Request to the AC.
+
+   o  Upon receiving the Join Request, the AC uses the following
+      process:
+
+      o  The AC creates the Join Response, and ensures that the Session
+         ID message element matches the value found in the Join Request.
+
+      o  If certificate-based security is used, the AC:
+
+         o  adds the Certificate-AC to the Certificate message element.
+
+         o  creates a random 'AC Nonce' and encrypts it using the
+            following algorithm E-wtp(Kpub, XNonce XOR 'AC Nonce').  The
+            encrypted contents are added to the ANonce's message element
+            payload.
+
+      o  If a pre-shared-key-based security is used, the AC:
+
+         o  creates RK0 through the following algorithm: RK0 = KDF-
+            256{PSK, "LWAPP PSK Top K0" || Session ID || WTP-MAC || AC-
+            MAC}, where WTP-MAC is the WTP's MAC address in the form
+            "xx:xx:xx:xx:xx:xx".  Similarly, the AC-MAC is an ASCII
+            encoding of the AC's MAC address, of the form "xx:xx:xx:xx:
+            xx:xx".  The resulting K0 is split into the following:
+
+            o  The first 16 octets are known as RK0E, and are used as an
+               encryption key.
+
+            o  The second 16 octets are known as RK0M, and are used for
+               MIC'ing purposes.
+
+         o  The AC creates a random 'AC Nonce' and encrypts it using the
+            following algorithm: AES-E(RK0E, XNonce XOR 'AC Nonce').
+            The encrypted contents are added to the ANonce's message
+            element payload.
+
+         o  The AC adds a MIC to the contents of the Join Response using
+            AES-CMAC(RK0M, Join Response) and adds the resulting hash to
+            the PSK-MIC (Section 6.2.9) message element.
+
+   o  Upon receiving the Join Response, the WTP uses the following
+      process:
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 78]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      o  If a pre-shared key is used, the WTP authenticates the Join
+         Response's PSK-MIC message element.  If authentication fails,
+         the packet is dropped.
+
+      o  The WTP decrypts the ANonce message element and XOR's the value
+         with XNonce to retrieve the 'AC Nonce'.  The ANonce payload is
+         referred to as ciphertext below:
+
+         o  If a pre-shared key is used, use AES-D(RK0E, ciphertext).
+            The 'AC Nonce' is then recovered using XNonce XOR plaintext.
+
+         o  If certificates are used, use d-wtp(Kpriv, ciphertext).  The
+            'AC Nonce' is then recovered using XNonce XOR plaintext.
+
+      o  The WTP creates a random 'WTP Nonce'.
+
+      o  The WTP uses the KDF function to create a 64-octet session key
+         (SK).  The KDF function used is as follows: KDF-512{'WTP Nonce'
+         || 'AC Nonce', "LWAPP Key Generation", WTP-MAC || AC-MAC}.  The
+         KDF function is defined in [7].
+
+      o  SK is then broken down into three separate session keys with
+         different purposes:
+
+         o  The first 16 octets are known as SK1C, and are used as a
+            confirmation key.
+
+         o  The second 16 octets are known as SK1E, and are as the
+            encryption key.
+
+         o  The third 16 octets are known as SK1D, and are used as the
+            keywrap key.
+
+         o  The fourth 16 octets are known as IV, and are used as the
+            Initialization Vector during encryption.
+
+      o  The WTP creates the Join ACK message.
+
+      o  If certificate-based security is used, the AC:
+
+         o  encrypts the 'WTP Nonce' using the following algorithm: E-
+            ac(Kpub, 'WTP Nonce').  The encrypted contents are added to
+            the WNonce's message element payload.
+
+      o  If a pre-shared-key-based security is used, the AC:
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 79]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+         o  encrypts the 'WTP Nonce' using the following algorithm:
+            AES-E(RK0E, 'WTP Nonce').  The encrypted contents are added
+            to the WNonce's message element payload.
+
+      o  The WTP adds a MIC to the contents of the Join ACK using
+         AES-CMAC(SK1M, Join ACK) and adds the resulting hash to the
+         PSK-MIC (Section 6.2.9) message element.
+
+      o  The WTP then transmits the Join ACK to the AC.
+
+   o  Upon receiving the Join ACK, the AC uses the following process:
+
+      o  The AC authenticates the Join ACK through the PSK-MIC message
+         element.  If authentic, the AC decrypts the WNonce message
+         element to retrieve the 'WTP Nonce'.  If the Join ACK cannot be
+         authenticated, the packet is dropped.
+
+      o  The AC decrypts the WNonce message element to retrieve the 'WTP
+         Nonce'.  The WNonce payload is referred to as ciphertext below:
+
+         o  If a pre-shared key is used, use AES-D(RK0E, ciphertext).
+            The plaintext is then considered the 'WTP Nonce'.
+
+         o  If certificates are used, use d-ac(Kpriv, ciphertext).  The
+            plaintext is then considered the 'WTP Nonce'.
+
+      o  The AC then uses the KDF function to create a 64-octet session
+         key (SK).  The KDF function used is as follows: KDF-512{'WTP
+         Nonce' || 'AC Nonce', "LWAPP Key Generation", WTP-MAC ||
+         AC-MAC}.  The KDF function is defined in [7].  The SK is split
+         into SK1C, SK1E, SK1D, and IV, as previously noted.
+
+      o  The AC creates the Join Confirm.
+
+      o  The AC adds a MIC to the contents of the Join Confirm using
+         AES-CMAC(SK1M, Join Confirm) and adds the resulting hash to the
+         MIC (Section 6.2.9) message element.
+
+      o  The AC then transmits the Join Confirm to the WTP.
+
+   o  Upon receiving the Join Confirm, the WTP uses the following
+      process:
+
+      o  The WTP authenticates the Join Confirm through the PSK-MIC
+         message element.  If the Join Confirm cannot be authenticated,
+         the packet is dropped.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 80]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   o  SK1E is now plumbed into the AC and WTP's crypto engine as the
+      AES-CCM LWAPP control encryption session key.  Furthermore, the
+      random IV is used as the base Initialization Vector.  From this
+      point on, all control protocol payloads between the WTP and AC are
+      encrypted and authenticated using the new session key.
+
+10.3.3.  Refreshing Cryptographic Keys
+
+   Since AC-WTP associations will tend to be relatively long-lived, it
+   is sensible to periodically refresh the encryption and authentication
+   keys; this is referred to as "rekeying".  When the key lifetime
+   reaches 95% of the configured value, identified in the KeyLifetime
+   timer (see Section 12), the rekeying will proceed as follows:
+
+   o  The WTP creates RK0 through the previously defined KDF algorithm:
+      RK0 = KDF-256{SK1D, "LWAPP PSK Top K0" || Session ID || WTP-MAC ||
+      AC-MAC}.  Note that the difference in this specific instance is
+      that SK1D that was previously generated is used instead of the
+      PSK.  Note this is used in both the certificate and pre-shared key
+      modes.  The resulting RK0 creates RK0E, RK0M.
+
+   o  The remaining steps used are identical to the join process, with
+      the exception that the rekey messages are used instead of join
+      messages, and the fact that the messages are encrypted using the
+      previously created SK1E.  This means the Join Request is replaced
+      with the Rekey Request, the Join Response is replaced with the
+      Rekey Response, etc.  The two differences between the rekey and
+      the join process are:
+
+      o  The Certificate-WTP and Certificate-AC are not included in the
+         Rekey-Request and Rekey-Response, respectively.
+
+      o  Regardless of whether certificates or pre-shared keys were used
+         in the initial key derivation, the process now uses the pre-
+         shared key mode only, using SK1D as the "PSK".
+
+   o  The Key Update Request is sent to the AC.
+
+   o  The newly created SK1E is now plumbed into the AC and WTP's crypto
+      engine as the AES-CCM LWAPP control encryption session key.
+      Furthermore, the new random IV is used as the base Initialization
+      Vector.  From this point on, all control protocol payloads between
+      the WTP and AC are encrypted and authenticated using the new
+      session key.
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 81]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      If either the WTP or the AC do not receive an expected response by
+      the time the ResponseTimeout timer expires (see Section 12), the
+      WTP MUST delete the new and old session information, and reset the
+      state machine to the Idle state.
+
+      Following a rekey process, both the WTP and the AC keep the
+      previous encryption for 5-10 seconds in order to be able to
+      process packets that arrive out of order.
+
+10.4.  Certificate Usage
+
+   Validation of the certificates by the AC and WTP is required so that
+   only an AC may perform the functions of an AC and that only a WTP may
+   perform the functions of a WTP.  This restriction of functions to the
+   AC or WTP requires that the certificates used by the AC MUST be
+   distinguishable from the certificate used by the WTP.  To accomplish
+   this differentiation, the x.509v3 certificates MUST include the
+   Extensions field [10] and MUST include the NetscapeComment [11]
+   extension.
+
+   For an AC, the value of the NetscapeComment extension MUST be the
+   string "CAPWAP AC Device Certificate".  For a WTP, the value of the
+   NetscapeComment extension MUST be the string "CAPWAP WTP Device
+   Certificate".
+
+   Part of the LWAPP certificate validation process includes ensuring
+   that the proper string is included in the NetscapeComment extension,
+   and only allowing the LWAPP session to be established if the
+   extension does not represent the same role as the device validating
+   the certificate.  For instance, a WTP MUST NOT accept a certificate
+   whose NetscapeComment field is set to "CAPWAP WTP Device
+   Certificate".
+
+11.  IEEE 802.11 Binding
+
+   This section defines the extensions required for the LWAPP protocol
+   to be used with the IEEE 802.11 protocol.
+
+11.1.  Division of Labor
+
+   The LWAPP protocol, when used with IEEE 802.11 devices, requires a
+   specific behavior from the WTP and the AC, specifically in terms of
+   which 802.11 protocol functions are handled.
+
+   For both the Split and Local MAC approaches, the CAPWAP functions, as
+   defined in the taxonomy specification, reside in the AC.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 82]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+11.1.1.  Split MAC
+
+   This section shows the division of labor between the WTP and the AC
+   in a Split MAC architecture.  Figure 3 shows the clear separation of
+   functionality among LWAPP components.
+
+       Function                               Location
+           Distribution Service                      AC
+           Integration Service                       AC
+           Beacon Generation                         WTP
+           Probe Response                            WTP
+           Power Mgmt/Packet Buffering               WTP
+           Fragmentation/Defragmentation             WTP
+           Assoc/Disassoc/Reassoc                    AC
+
+      802.11e
+           Classifying                               AC
+           Scheduling                                WTP/AC
+           Queuing                                   WTP
+
+      802.11i
+           802.1X/EAP                                AC
+           Key Management                            AC
+           802.11 Encryption/Decryption              WTP or AC
+
+       Figure 3: Mapping of 802.11 Functions for Split MAC Architecture
+
+   The Distribution and Integration services reside on the AC, and
+   therefore all user data is tunneled between the WTP and the AC.  As
+   noted above, all real-time 802.11 services, including the control
+   protocol and the beacon and Probe Response frames, are handled on the
+   WTP.
+
+   All remaining 802.11 MAC management frames are supported on the AC,
+   including the Association Request, which allows the AC to be involved
+   in the access policy enforcement portion of the 802.11 protocol.  The
+   802.1X and 802.11i key management function are also located on the
+   AC.
+
+   While the admission control component of 802.11e resides on the AC,
+   the real-time scheduling and queuing functions are on the WTP.  Note
+   that this does not exclude the AC from providing additional policing
+   and scheduling functionality.
+
+   Note that in the following figure, the use of '( - )' indicates that
+   processing of the frames is done on the WTP.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 83]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      Client                       WTP                        AC
+
+               Beacon
+      <-----------------------------
+            Probe Request
+      ----------------------------( - )------------------------->
+            Probe Response
+      <-----------------------------
+                       802.11 AUTH/Association
+      <--------------------------------------------------------->
+                         Add Mobile (Clear Text, 802.1X Only)
+                                      <------------------------->
+             802.1X Authentication & 802.11i Key Exchange
+      <--------------------------------------------------------->
+                                  Add Mobile (AES-CCMP, PTK=x)
+                                      <------------------------->
+                        802.11 Action Frames
+      <--------------------------------------------------------->
+                            802.11 DATA (1)
+      <---------------------------( - )------------------------->
+
+                       Figure 4: Split MAC Message Flow
+
+   Figure 4 provides an illustration of the division of labor in a Split
+   MAC architecture.  In this example, a WLAN has been created that is
+   configured for 802.11i, using AES-CCMP for privacy.  The following
+   process occurs:
+
+   o  The WTP generates the 802.11 beacon frames, using information
+      provided to it through the Add WLAN (see Section 11.8.1.1) message
+      element.
+
+   o  The WTP processes the Probe Request and responds with a
+      corresponding Probe Response.  The problem request is then
+      forwarded to the AC for optional processing.
+
+   o  The WTP forwards the 802.11 Authentication and Association frames
+      to the AC, which is responsible for responding to the client.
+
+   o  Once the association is complete, the AC transmits an LWAPP Add
+      Mobile Request to the WTP (see Section 11.7.1.1).  In the above
+      example, the WLAN is configured for 802.1X, and therefore the
+      '802.1X only' policy bit is enabled.
+
+   o  If the WTP is providing encryption/decryption services, once the
+      client has completed the 802.11i key exchange, the AC transmits
+      another Add Mobile Request to the WTP, stating the security policy
+      to enforce for the client (in this case AES-CCMP), as well as the
+
+
+
+Calhoun, et al.                 Historic                       [Page 84]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      encryption key to use.  If encryption/decryption is handled in the
+      AC, the Add Mobile Request would have the encryption policy set to
+      "Clear Text".
+
+   o  The WTP forwards any 802.11 Action frames received to the AC.
+
+   o  All client data frames are tunneled between the WTP and the AC.
+      Note that the WTP is responsible for encrypting and decrypting
+      frames, if it was indicated in the Add Mobile Request.
+
+11.1.2.  Local MAC
+
+   This section shows the division of labor between the WTP and the AC
+   in a Local MAC architecture.  Figure 5 shows the clear separation of
+   functionality among LWAPP components.
+
+       Function                               Location
+           Distribution Service                      WTP
+           Integration Service                       WTP
+           Beacon Generation                         WTP
+           Probe Response                            WTP
+           Power Mgmt/Packet Buffering               WTP
+           Fragmentation/Defragmentation             WTP
+           Assoc/Disassoc/Reassoc                    WTP
+
+      802.11e
+           Classifying                               WTP
+           Scheduling                                WTP
+           Queuing                                   WTP
+
+      802.11i
+           802.1X/EAP                                AC
+           Key Management                            AC
+           802.11 Encryption/Decryption              WTP
+
+      Figure 5: Mapping of 802.11 Functions for Local AP Architecture
+
+   Given that Distribution and Integration Services exist on the WTP,
+   client data frames are not forwarded to the AC, with the exception
+   listed in the following paragraphs.
+
+   While the MAC is terminated on the WTP, it is necessary for the AC to
+   be aware of mobility events within the WTPs.  As a consequence, the
+   WTP MUST forward the 802.11 Association Requests to the AC, and the
+   AC MAY reply with a failed Association Response if it deems it
+   necessary.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 85]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   The 802.1X and 802.11i Key Management function resides in the AC.
+   Therefore, the WTP MUST forward all 802.1X/Key Management frames to
+   the AC and forward the associated responses to the station.
+
+   Note that in the following figure, the use of '( - )' indicates that
+   processing of the frames is done on the WTP.
+
+
+      Client                       WTP                        AC
+
+               Beacon
+      <-----------------------------
+                Probe
+      <---------------------------->
+             802.11 AUTH
+      <-----------------------------
+                          802.11 Association
+      <---------------------------( - )------------------------->
+                         Add Mobile (Clear Text, 802.1X Only)
+                                      <------------------------->
+             802.1X Authentication & 802.11i Key Exchange
+      <--------------------------------------------------------->
+                        802.11 Action Frames
+      <--------------------------------------------------------->
+                                  Add Mobile (AES-CCMP, PTK=x)
+                                      <------------------------->
+              802.11 DATA
+      <----------------------------->
+
+                       Figure 6: Local MAC Message Flow
+
+   Figure 6 provides an illustration of the division of labor in a Local
+   MAC architecture.  In this example, a WLAN has been created that is
+   configured for 802.11i, using AES-CCMP for privacy.  The following
+   process occurs:
+
+   o  The WTP generates the 802.11 beacon frames, using information
+      provided to it through the Add WLAN (see Section 11.8.1.1) message
+      element.
+
+   o  The WTP processes the Probe Request and responds with a
+      corresponding Probe Response.
+
+   o  The WTP forwards the 802.11 Authentication and Association frames
+      to the AC, which is responsible for responding to the client.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 86]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   o  Once the association is complete, the AC transmits an LWAPP Add
+      Mobile Request to the WTP (see Section 11.7.1.1.  In the above
+      example, the WLAN is configured for 802.1X, and therefore the
+      '802.1X only' policy bit is enabled.
+
+   o  The WTP forwards all 802.1X and 802.11i key exchange messages to
+      the AC for processing.
+
+   o  The AC transmits another Add Mobile Request to the WTP, stating
+      the security policy to enforce for the client (in this case, AES-
+      CCMP), as well as the encryption key to use.  The Add Mobile
+      Request MAY include a VLAN name, which when present is used by the
+      WTP to identify the VLAN on which the user's data frames are to be
+      bridged.
+
+   o  The WTP forwards any 802.11 Action frames received to the AC.
+
+   o  The WTP locally bridges all client data frames, and provides the
+      necessary encryption and decryption services.
+
+11.2.  Roaming Behavior and 802.11 Security
+
+   It is important that LWAPP implementations react properly to mobile
+   devices associating to the networks in how they generate Add Mobile
+   and Delete Mobile messages.  This section expands upon the examples
+   provided in the previous section, and describes how the LWAPP control
+   protocol is used in order to provide secure roaming.
+
+   Once a client has successfully associated with the network in a
+   secure fashion, it is likely to attempt to roam to another access
+   point.  Figure 7 shows an example of a currently associated station
+   moving from its "Old WTP" to a new "WTP".  The figure is useful for
+   multiple different security policies, including standard 802.1X and
+   dynamic WEP keys, WPA or even WPA2 both with key caching (where the
+   802.1x exchange would be bypassed) and without.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 87]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      Client              Old WTP              WTP              AC
+
+                    Association Request/Response
+       <--------------------------------------( - )-------------->
+                          Add Mobile (Clear Text, 802.1X Only)
+                                                <---------------->
+       802.1X Authentication (if no key cache entry exists)
+       <--------------------------------------( - )-------------->
+                     802.11i 4-way Key Exchange
+       <--------------------------------------( - )-------------->
+                                   Delete Mobile
+                              <---------------------------------->
+                                   Add Mobile (AES-CCMP, PTK=x)
+                                                <---------------->
+
+                       Figure 7: Client Roaming Example
+
+11.3.  Transport-Specific Bindings
+
+   All LWAPP transports have the following IEEE 802.11 specific
+   bindings:
+
+11.3.1.  Status and WLANS Field
+
+   The interpretation of this 16-bit field depends on the direction of
+   transmission of the packet.  Refer to the figure in Section 3.1.
+
+   Status
+
+   When an LWAPP packet is transmitted from a WTP to an AC, this field
+   is called the Status field and indicates radio resource information
+   associated with the frame.  When the message is an LWAPP control
+   message this field is transmitted as zero.
+
+   The Status field is divided into the signal strength and signal-to-
+   noise ratio with which an IEEE 802.11 frame was received, encoded in
+   the following manner:
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     RSSI      |     SNR       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   RSSI:   RSSI is a signed, 8-bit value.  It is the received signal
+      strength indication, in dBm.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 88]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   SNR:   SNR is a signed, 8-bit value.  It is the signal-to-noise ratio
+      of the received IEEE 802.11 frame, in dB.
+
+   WLANs field:   When an LWAPP data message is transmitted from an AC
+      to a WTP, this 16-bit field indicates on which WLANs the
+      encapsulated IEEE 802.11 frame is to be transmitted.  For unicast
+      packets, this field is not used by the WTP.  For broadcast or
+      multicast packets, the WTP might require this information if it
+      provides encryption services.
+
+      Given that a single broadcast or multicast packet might need to be
+      sent to multiple wireless LANs (presumably each with a different
+      broadcast key), this field is defined as a bit field.  A bit set
+      indicates a WLAN ID (see Section 11.8.1.1), which will be sent the
+      data.  The WLANS field is encoded in the following manner:
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |          WLAN ID(s)           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+11.4.  BSSID to WLAN ID Mapping
+
+   The LWAPP protocol makes assumptions regarding the BSSIDs used on the
+   WTP.  It is a requirement for the WTP to use a contiguous block of
+   BSSIDs.  The WLAN Identifier field, which is managed by the AC, is
+   used as an offset into the BSSID list.
+
+   For instance, if a WTP had a base BSSID address of 00:01:02:00:00:00,
+   and the AC sent an Add WLAN message with a WLAN Identifier of 2 (see
+   Section 11.8.1.1), the BSSID for the specific WLAN on the WTP would
+   be 00:01:02:00:00:02.
+
+   The WTP communicates the maximum number of BSSIDs that it supports
+   during the Config Request within the IEEE 802.11 WTP WLAN Radio
+   Configuration message element (see Section 11.9.1).
+
+11.5.  Quality of Service
+
+   It is recommended that 802.11 MAC management be sent by both the AC
+   and the WTP with appropriate Quality-of-Service (QoS) values,
+   ensuring that congestion in the network minimizes occurrences of
+   packet loss.  Therefore, a QoS-enabled LWAPP device should use:
+
+   802.1P:   The precedence value of 6 SHOULD be used for all 802.11 MAC
+      management messages, except for Probe Requests, which SHOULD use
+      4.
+
+
+
+Calhoun, et al.                 Historic                       [Page 89]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   DSCP:   The DSCP tag value of 46 SHOULD be used for all 802.11 MAC
+      management messages, except for Probe Requests, which SHOULD use
+      34.
+
+11.6.  Data Message Bindings
+
+   There are no LWAPP data message bindings for IEEE 802.11.
+
+11.7.  Control Message Bindings
+
+   The IEEE 802.11 binding has the following control message
+   definitions.
+
+11.7.1.  Mobile Config Request
+
+   This section contains the 802.11-specific message elements that are
+   used with the Mobile Config Request.
+
+11.7.1.1.  Add Mobile
+
+   The Add Mobile Request is used by the AC to inform a WTP that it
+   should forward traffic from a particular mobile station.  The Add
+   Mobile Request may also include security parameters that must be
+   enforced by the WTP for the particular mobile.
+
+   When the AC sends an Add Mobile Request, it includes any security
+   parameters that may be required.  An AC that wishes to update a
+   mobile's policy on a WTP may do so by simply sending a new Add Mobile
+   message element.
+
+   When a WTP receives an Add Mobile message element, it must first
+   override any existing state it may have for the mobile station in
+   question.  The latest Add Mobile overrides any previously received
+   messages.  If the Add Mobile message element's EAP-Only bit is set,
+   the WTP MUST drop all 802.11 packets that do not contain EAP packets.
+   Note that when EAP Only is set, the Encryption Policy field MAY have
+   additional values, and therefore it is possible to inform a WTP to
+   only accept encrypted EAP packets.  Once the mobile station has
+   successfully completed EAP authentication, the AC must send a new Add
+   Mobile message element to push the session key down to the WTP as
+   well as to remove the EAP Only restriction.
+
+   If the QoS field is set, the WTP MUST observe and provide policing of
+   the 802.11e priority tag to ensure that it does not exceed the value
+   provided by the AC.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 90]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |        Association ID         |  MAC Address  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          MAC Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  MAC Address  |E|C|            Encryption Policy              |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |Encrypt Policy |                Session Key...                 |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                        Pairwise TSC...                        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                        Pairwise RSC...                        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |          Capabilities         |   WLAN ID     |    WME Mode   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | 802.11e Mode  |      Qos      |        Supported Rates        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                        Supported Rates                        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |          VLAN Name...
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   29 for Add Mobile
+
+   Length:   36
+
+   Radio ID:   An 8-bit value representing the radio.
+
+   Association ID:   A 16-bit value specifying the 802.11 Association
+      Identifier.
+
+   MAC Address:   The mobile station's MAC address.
+
+   E:   The 1-bit field is set by the AC to inform the WTP that it MUST
+      NOT accept any 802.11 data frames, other than 802.1X frames.  This
+      is the equivalent of the WTP's 802.1X port for the mobile station
+      to be in the closed state.  When set, the WTP MUST drop any
+      non-802.1X packets it receives from the mobile station.
+
+   C:   The 1-bit field is set by the AC to inform the WTP that
+      encryption services will be provided by the AC.  When set, the WTP
+      SHOULD police frames received from stations to ensure that they
+      comply to the stated encryption policy, but does not need to take
+      specific cryptographic action on the frame.  Similarly, for
+      transmitted frames, the WTP only needs to forward already
+      encrypted frames.
+
+
+
+Calhoun, et al.                 Historic                       [Page 91]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Encryption Policy:   The policy field informs the WTP how to handle
+      packets from/to the mobile station.  The following values are
+      supported:
+
+      0 -  Encrypt WEP 104: All packets to/from the mobile station must
+           be encrypted using a standard 104-bit WEP.
+
+      1 -  Clear Text: All packets to/from the mobile station do not
+           require any additional crypto processing by the WTP.
+
+      2 -  Encrypt WEP 40: All packets to/from the mobile station must
+           be encrypted using a standard 40-bit WEP.
+
+      3 -  Encrypt WEP 128: All packets to/from the mobile station must
+           be encrypted using a standard 128-bit WEP.
+
+      4 -  Encrypt AES-CCMP 128: All packets to/from the mobile station
+           must be encrypted using a 128-bit AES-CCMP [7].
+
+      5 -  Encrypt TKIP-MIC: All packets to/from the mobile station must
+           be encrypted using Temporal Key Integrity Protocol (TKIP) and
+           authenticated using Michael [16].
+
+   Session Key:   A 32-octet session key the WTP is to use when
+      encrypting traffic to or decrypting traffic from the mobile
+      station.  The type of key is determined based on the Encryption
+      Policy field.
+
+   Pairwise TSC:   The TKIP Sequence Counter (TSC) to use for unicast
+      packets transmitted to the mobile.
+
+   Pairwise RSC:   The Receive Sequence Counter (RSC) to use for unicast
+      packets received from the mobile.
+
+   Capabilities:   A 16-bit field containing the 802.11 capabilities to
+      use with the mobile.
+
+   WLAN ID:   An 8-bit value specifying the WLAN Identifier.
+
+   WME Mode:   An 8-bit Boolean used to identify whether the station is
+      WME capable.  A value of zero is used to indicate that the station
+      is not Wireless Multimedia Extension (WME) capable, while a value
+      of one means that the station is WME capable.
+
+   802.11e Mode:   An 8-bit Boolean used to identify whether the station
+      is 802.11e-capable.  A value of zero is used to indicate that the
+      station is not 802.11e-capable, while a value of one means that
+      the station is 802.11e-capable.
+
+
+
+Calhoun, et al.                 Historic                       [Page 92]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   QoS:   An 8-bit value specifying the QoS policy to enforce for the
+      station.  The following values are supported: PRC: TO CHECK
+
+      0 -  Silver (Best Effort)
+
+      1 -  Gold (Video)
+
+      2 -  Platinum (Voice)
+
+      3 -  Bronze (Background)
+
+   Supported Rates:   The supported rates to be used with the mobile
+      station.
+
+   VLAN Name:   An optional variable string containing the VLAN Name on
+      which the WTP is to locally bridge user data.  Note that this
+      field is only valid with Local MAC WTPs.
+
+11.7.1.2.  IEEE 802.11 Mobile Session Key
+
+   The Mobile Session Key Payload message element is sent when the AC
+   determines that encryption of a mobile station must be performed in
+   the WTP.  This message element MUST NOT be present without the Add
+   Mobile message element, and MUST NOT be sent if the WTP had not
+   specifically advertised support for the requested encryption scheme
+   (see Section 11.7.1.1).
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           MAC Address                         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |          MAC Address          |       Encryption Policy       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |       Encryption Policy       |        Session Key...         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   105 for IEEE 802.11 Mobile Session Key
+
+   Length:   >= 11
+
+   MAC Address: The mobile station's MAC address.
+
+   Encryption Policy: The policy field informs the WTP how to handle
+      packets from/to the mobile station.  The following values are
+      supported:
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 93]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      0 -  Encrypt WEP 104: All packets to/from the mobile station must
+           be encrypted using a standard 104-bit WEP.
+
+      1 -  Clear Text: All packets to/from the mobile station do not
+           require any additional crypto processing by the WTP.
+
+      2 -  Encrypt WEP 40: All packets to/from the mobile station must
+           be encrypted using a standard 40-bit WEP.
+
+      3 -  Encrypt WEP 128: All packets to/from the mobile station must
+           be encrypted using a standard 128-bit WEP.
+
+      4 -  Encrypt AES-CCMP 128: All packets to/from the mobile station
+           must be encrypted using a 128-bit AES-CCMP [7].
+
+      5 -  Encrypt TKIP-MIC: All packets to/from the mobile station must
+           be encrypted using TKIP and authenticated using Michael [16].
+
+   Session Key: The session key the WTP is to use when encrypting
+      traffic to/from the mobile station.
+
+11.7.1.3.  Station QoS Profile
+
+   The Station QoS Profile Payload message element contains the maximum
+   802.11e priority tag that may be used by the station.  Any packets
+   received that exceed the value encoded in this message element must
+   either be dropped or tagged using the maximum value permitted to the
+   user.  The priority tag must be between zero (0) and seven (7).
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                           MAC Address                         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |          MAC Address          |     802.1P Precedence Tag     |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   140 for IEEE 802.11 Station QoS Profile
+
+   Length:   12
+
+   MAC Address:   The mobile station's MAC address.
+
+   802.1P Precedence Tag:   The maximum 802.1P precedence value that the
+      WTP will allow in the Traffic Identifier (TID) field in the
+      extended 802.11e QoS Data header.
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 94]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+11.7.1.4.  IEEE 802.11 Update Mobile QoS
+
+   The Update Mobile QoS message element is used to change the Quality-
+   of-Service policy on the WTP for a given mobile station.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Radio ID    |        Association ID         |  MAC Address  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          MAC Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  MAC Address  |  QoS Profile  |        Vlan Identifier        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   DSCP Tag    |  802.1P Tag   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   106 for IEEE 802.11 Update Mobile QoS
+
+   Length:   14
+
+   Radio ID:   The Radio Identifier, typically refers to some interface
+      index on the WTP.
+
+   Association ID:   The 802.11 Association Identifier.
+
+   MAC Address:   The mobile station's MAC address.
+
+   QoS Profile:   An 8-bit value specifying the QoS policy to enforce
+      for the station.  The following values are supported:
+
+      0 -  Silver (Best Effort)
+
+      1 -  Gold (Video)
+
+      2 -  Platinum (Voice)
+
+      3 -  Bronze (Background)
+
+   VLAN Identifier:   PRC.
+
+   DSCP Tag:   The DSCP label to use if packets are to be DSCP tagged.
+
+   802.1P Tag:   The 802.1P precedence value to use if packets are to be
+      802.1P-tagged.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 95]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+11.7.2.  WTP Event Request
+
+   This section contains the 802.11-specific message elements that are
+   used with the WTP Event Request message.
+
+11.7.2.1.  IEEE 802.11 Statistics
+
+   The Statistics message element is sent by the WTP to transmit its
+   current statistics.  The value contains the following fields:
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |               Tx Fragment Count               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |Tx Fragment Cnt|               Multicast Tx Count              |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | Mcast Tx Cnt  |                  Failed Count                 |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | Failed Count  |                  Retry Count                  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  Retry Count  |             Multiple Retry Count              |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |Multi Retry Cnt|             Frame Duplicate Count             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | Frame Dup Cnt |               RTS Success Count               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |RTS Success Cnt|               RTS Failure Count               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |RTS Failure Cnt|               ACK Failure Count               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |ACK Failure Cnt|               Rx Fragment Count               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |Rx Fragment Cnt|               Multicast RX Count              |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | Mcast Rx Cnt  |                FCS Error  Count               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | FCS Error  Cnt|                 Tx Frame Count                |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | Tx Frame Cnt  |               Decryption Errors               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |Decryption Errs|
+      +-+-+-+-+-+-+-+-+
+
+   Type:   38 for Statistics
+
+   Length:   57
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 96]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Radio ID:   An 8-bit value representing the radio.
+
+   Tx Fragment Count:   A 32-bit value representing the number of
+      fragmented frames transmitted.
+
+   Multicast Tx Count:   A 32-bit value representing the number of
+      multicast frames transmitted.
+
+   Failed Count:   A 32-bit value representing the transmit excessive
+      retries.
+
+   Retry Count:   A 32-bit value representing the number of transmit
+      retries.
+
+   Multiple Retry Count:   A 32-bit value representing the number of
+      transmits that required more than one retry.
+
+   Frame Duplicate Count:   A 32-bit value representing the duplicate
+      frames received.
+
+   RTS Success Count:   A 32-bit value representing the number of
+      successfully transmitted Ready To Send (RTS).
+
+   RTS Failure Count:   A 32-bit value representing the failed
+      transmitted RTS.
+
+   ACK Failure Count:   A 32-bit value representing the number of failed
+      acknowledgements.
+
+   Rx Fragment Count:   A 32-bit value representing the number of
+      fragmented frames received.
+
+   Multicast RX Count:   A 32-bit value representing the number of
+      multicast frames received.
+
+   FCS Error Count:   A 32-bit value representing the number of Frame
+      Check Sequence (FCS) failures.
+
+   Decryption Errors:   A 32-bit value representing the number of
+      Decryption errors that occurred on the WTP.  Note that this field
+      is only valid in cases where the WTP provides encryption/
+      decryption services.
+
+11.8.  802.11 Control Messages
+
+   This section will define LWAPP control messages that are specific to
+   the IEEE 802.11 binding.
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 97]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+11.8.1.  IEEE 802.11 WLAN Config Request
+
+   The IEEE 802.11 WLAN Configuration Request is sent by the AC to the
+   WTP in order to change services provided by the WTP.  This control
+   message is used to either create, update, or delete a WLAN on the
+   WTP.
+
+   The IEEE 802.11 WLAN Configuration Request is sent as a result of
+   either some manual administrative process (e.g., deleting a WLAN), or
+   automatically to create a WLAN on a WTP.  When sent automatically to
+   create a WLAN, this control message is sent after the LWAPP
+   Configuration Request message has been received by the WTP.
+
+   Upon receiving this control message, the WTP will modify the
+   necessary services, and transmit an IEEE 802.11 WLAN Configuration
+   Response.
+
+   An WTP MAY provide service for more than one WLAN: therefore, every
+   WLAN is identified through a numerical index.  For instance, a WTP
+   that is capable of supporting up to 16 SSIDs could accept up to 16
+   IEEE 802.11 WLAN Configuration Request messages that include the Add
+   WLAN message element.
+
+   Since the index is the primary identifier for a WLAN, an AC SHOULD
+   attempt to ensure that the same WLAN is identified through the same
+   index number on all of its WTPs.  An AC that does not follow this
+   approach MUST find some other means of maintaining a WLAN Identifier
+   to SSID mapping table.
+
+   The following subsections define the message elements that are of
+   value for this LWAPP operation.  Only one message MUST be present.
+
+11.8.1.1.  IEEE 802.11 Add WLAN
+
+   The Add WLAN message element is used by the AC to define a wireless
+   LAN on the WTP.  The value contains the following format:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 98]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |         WLAN Capability       |    WLAN ID    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                      Encryption Policy                        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Key ...                           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Key Index   |   Shared Key  | WPA Data Len  |WPA IE Data ...|
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | RSN Data Len  |RSN IE Data ...|         Reserved ....         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | WME Data Len  |WME IE Data ...|  11e Data Len |11e IE Data ...|
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      QoS      |   Auth Type   |Broadcast SSID |  Reserved...  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    SSID ...   |
+      +-+-+-+-+-+-+-+-+
+
+   Type:   7 for IEEE 802.11 Add WLAN
+
+   Length:   >= 298
+
+   Radio ID:   An 8-bit value representing the radio.
+
+   WLAN Capability:   A 16-bit value containing the capabilities to be
+      advertised by the WTP within the Probe and Beacon messages.
+
+   WLAN ID:   A 16-bit value specifying the WLAN Identifier.
+
+   Encryption Policy:   A 32-bit value specifying the encryption scheme
+      to apply to traffic to and from the mobile station.
+
+      The following values are supported:
+
+      0 -  Encrypt WEP 104: All packets to/from the mobile station must
+           be encrypted using a standard 104-bit WEP.
+
+      1 -  Clear Text: All packets to/from the mobile station do not
+           require any additional crypto processing by the WTP.
+
+      2 -  Encrypt WEP 40: All packets to/from the mobile station must
+           be encrypted using a standard 40-bit WEP.
+
+      3 -  Encrypt WEP 128: All packets to/from the mobile station must
+           be encrypted using a standard 128-bit WEP.
+
+
+
+
+Calhoun, et al.                 Historic                       [Page 99]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      4 -  Encrypt AES-CCMP 128: All packets to/from the mobile station
+           must be encrypted using a 128-bit AES-CCMP [7].
+
+      5 -  Encrypt TKIP-MIC: All packets to/from the mobile station must
+           be encrypted using TKIP and authenticated using Michael [16].
+
+      6 -  Encrypt CKIP: All packets to/from the mobile station must be
+           encrypted using Cisco TKIP.
+
+   Key:   A 32-byte session key to use with the encryption policy.
+
+   Key-Index:   The Key Index associated with the key.
+
+   Shared Key:   A 1-byte Boolean that specifies whether the key
+      included in the Key field is a shared WEP key.  A value of zero is
+      used to state that the key is not a shared WEP key, while a value
+      of one is used to state that the key is a shared WEP key.
+
+   WPA Data Len:   Length of the WPA Information Element (IE).
+
+   WPA IE:   A 32-byte field containing the WPA Information Element.
+
+   RSN Data Len:   Length of the Robust Security Network (RSN) IE.
+
+   RSN IE:   A 64-byte field containing the RSN Information Element.
+
+   Reserved:   A 49-byte reserved field, which MUST be set to zero (0).
+
+   WME Data Len:   Length of the WME IE.
+
+   WME IE:   A 32-byte field containing the WME Information Element.
+
+   DOT11E Data Len:   Length of the 802.11e IE.
+
+   DOT11E IE:   A 32-byte field containing the 802.11e Information
+      Element.
+
+   QOS:   An 8-bit value specifying the QoS policy to enforce for the
+      station.
+
+      The following values are supported:
+
+      0 -  Silver (Best Effort)
+
+      1 -  Gold (Video)
+
+      2 -  Platinum (Voice)
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 100]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      3 -  Bronze (Background)
+
+   Auth Type:   An 8-bit value specifying the station's authentication
+      type.
+
+      The following values are supported:
+
+      0 -  Open System
+
+      1 -  WEP Shared Key
+
+      2 -  WPA/WPA2 802.1X
+
+      3 -  WPA/WPA2 PSK
+
+   Broadcast SSID:   A Boolean indicating whether the SSID is to be
+      broadcast by the WTP.  A value of zero disables SSID broadcast,
+      while a value of one enables it.
+
+   Reserved:   A 40-byte reserved field.
+
+   SSID:   The SSID attribute is the service set identifier that will be
+      advertised by the WTP for this WLAN.
+
+11.8.1.2.  IEEE 802.11 Delete WLAN
+
+   The Delete WLAN message element is used to inform the WTP that a
+   previously created WLAN is to be deleted.  The value contains the
+   following fields:
+
+       0                   1                   2
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |            WLAN ID            |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   28 for IEEE 802.11 Delete WLAN
+
+   Length:   3
+
+   Radio ID:   An 8-bit value representing the radio
+
+   WLAN ID:   A 16-bit value specifying the WLAN Identifier
+
+11.8.1.3.  IEEE 802.11 Update WLAN
+
+   The Update WLAN message element is used by the AC to define a
+   wireless LAN on the WTP.  The value contains the following format:
+
+
+
+Calhoun, et al.                 Historic                      [Page 101]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |             WLAN ID           |Encrypt Policy |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                      Encryption Policy        |     Key...    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             Key ...                           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Key Index   |   Shared Key  |        WLAN Capability        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   34 for IEEE 802.11 Update WLAN
+
+   Length:   43
+
+   Radio ID:   An 8-bit value representing the radio.
+
+   WLAN ID:   A 16-bit value specifying the WLAN Identifier.
+
+   Encryption Policy:   A 32-bit value specifying the encryption scheme
+      to apply to traffic to and from the mobile station.
+
+      The following values are supported:
+
+      0 -  Encrypt WEP 104: All packets to/from the mobile station must
+           be encrypted using a standard 104-bit WEP.
+
+      1 -  Clear Text: All packets to/from the mobile station do not
+           require any additional crypto processing by the WTP.
+
+      2 -  Encrypt WEP 40: All packets to/from the mobile station must
+           be encrypted using a standard 40-bit WEP.
+
+      3 -  Encrypt WEP 128: All packets to/from the mobile station must
+           be encrypted using a standard 128-bit WEP.
+
+      4 -  Encrypt AES-CCMP 128: All packets to/from the mobile station
+           must be encrypted using a 128-bit AES-CCMP [7].
+
+      5 -  Encrypt TKIP-MIC: All packets to/from the mobile station must
+           be encrypted using TKIP and authenticated using Michael [16].
+
+      6 -  Encrypt CKIP: All packets to/from the mobile station must be
+           encrypted using Cisco TKIP.
+
+   Key:   A 32-byte session key to use with the encryption policy.
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 102]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Key-Index:   The Key Index associated with the key.
+
+   Shared Key:   A 1-byte Boolean that specifies whether the key
+      included in the Key field is a shared WEP key.  A value of zero
+      means that the key is not a shared WEP key, while a value of one
+      is used to state that the key is a shared WEP key.
+
+   WLAN Capability:   A 16-bit value containing the capabilities to be
+      advertised by the WTP within the Probe and Beacon messages.
+
+11.8.2.  IEEE 802.11 WLAN Config Response
+
+   The IEEE 802.11 WLAN Configuration Response is sent by the WTP to the
+   AC as an acknowledgement of the receipt of an IEEE 802.11 WLAN
+   Configuration Request.
+
+   This LWAPP control message does not include any message elements.
+
+11.8.3.  IEEE 802.11 WTP Event
+
+   The IEEE 802.11 WTP Event LWAPP message is used by the WTP in order
+   to report asynchronous events to the AC.  There is no reply message
+   expected from the AC, except that the message is acknowledged via the
+   reliable transport.
+
+   When the AC receives the IEEE 802.11 WTP Event, it will take whatever
+   action is necessary, depending upon the message elements present in
+   the message.
+
+   The IEEE 802.11 WTP Event message MUST contain one of the following
+   message elements described in the next subsections.
+
+11.8.3.1.  IEEE 802.11 MIC Countermeasures
+
+   The MIC Countermeasures message element is sent by the WTP to the AC
+   to indicate the occurrence of a MIC failure.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Radio ID    |    WLAN ID    |          MAC Address          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                          MAC Address                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   61 for IEEE 802.11 MIC Countermeasures
+
+   Length:   8
+
+
+
+Calhoun, et al.                 Historic                      [Page 103]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Radio ID:   The Radio Identifier, typically refers to some interface
+      index on the WTP.
+
+   WLAN ID:   This 8-bit unsigned integer includes the WLAN Identifier,
+      on which the MIC failure occurred.
+
+   MAC Address:   The MAC address of the mobile station that caused the
+      MIC failure.
+
+11.8.3.2.  IEEE 802.11 WTP Radio Fail Alarm Indication
+
+   The WTP Radio Fail Alarm Indication message element is sent by the
+   WTP to the AC when it detects a radio failure.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Radio ID    |     Type      |    Status     |      Pad      |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   95 for WTP Radio Fail Alarm Indication
+
+   Length:   4
+
+   Radio ID:   The Radio Identifier, typically refers to some interface
+      index on the WTP.
+
+   Type:   The type of radio failure detected.  The following values are
+      supported:
+
+      1 -  Receiver
+
+      2 -  Transmitter
+
+   Status:   An 8-bit Boolean indicating whether the radio failure is
+      being reported or cleared.  A value of zero is used to clear the
+      event, while a value of one is used to report the event.
+
+   Pad:   Reserved field MUST be set to zero (0).
+
+
+
+
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 104]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+11.9.  Message Element Bindings
+
+   The IEEE 802.11 Message Element binding has the following
+   definitions:
+
+                                                Conf  Conf  Conf  Add
+                                                Req   Resp  Upd   Mobile
+
+      IEEE 802.11 WTP WLAN Radio Configuration   X     X     X
+      IEEE 802.11 Rate Set                             X     X
+      IEEE 802.11 Multi-domain Capability        X     X     X
+      IEEE 802.11 MAC Operation                  X     X     X
+      IEEE 802.11 Tx Power                       X     X     X
+      IEEE 802.11 Tx Power Level                 X
+      IEEE 802.11 Direct Sequence Control        X     X     X
+      IEEE 802.11 OFDM Control                   X     X     X
+      IEEE 802.11 Supported Rates                X     X
+      IEEE 802.11 Antenna                        X     X     X
+      IEEE 802.11 CFP Status                     X           X
+      IEEE 802.11 Broadcast Probe Mode                 X     X
+      IEEE 802.11 WTP Mode and Type              X?          X
+      IEEE 802.11 WTP Quality of Service               X     X
+      IEEE 802.11 MIC Error Report From Mobile               X
+      IEEE 802.11 Update Mobile QoS                                X
+      IEEE 802.11 Mobile Session Key                               X
+
+11.9.1.  IEEE 802.11 WTP WLAN Radio Configuration
+
+   The WTP WLAN radio configuration is used by the AC to configure a
+   Radio on the WTP.  The message element value contains the following
+   Fields:
+
+        0                   1                   2                   3
+        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |    Reserved   |        Occupancy Limit        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    CFP Per    |      CFP Maximum Duration     |     BSS ID    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                            BSS ID                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     BSS ID    |        Beacon Period          |    DTIM Per   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                        Country String                         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | Num Of BSSIDs |
+      +-+-+-+-+-+-+-+-+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 105]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Type:   8 for IEEE 802.11 WTP WLAN Radio Configuration
+
+   Length:   20
+
+   Radio ID:   An 8-bit value representing the radio to configure.
+
+   Reserved:   MUST be set to zero
+
+   Occupancy Limit:   This attribute indicates the maximum amount of
+      time, in Time Units (TUs), that a point coordinator MAY control
+      the usage of the wireless medium without relinquishing control for
+      long enough to allow at least one instance of Distributed
+      Coordination Function (DCF) access to the medium.  The default
+      value of this attribute SHOULD be 100, and the maximum value
+      SHOULD be 1000.
+
+   CFP Period:   The attribute describes the number of DTIM intervals
+      between the start of Contention-Free Periods (CFPs).
+
+   CFP Maximum Duration:   The attribute describes the maximum duration
+      of the CFP in TU that MAY be generated by the Point Coordination
+      Function (PCF).
+
+   BSSID:   The WLAN Radio's base MAC address.  For WTPs that support
+      more than a single WLAN, the value of the WLAN Identifier is added
+      to the last octet of the BSSID.  Therefore, a WTP that supports 16
+      WLANs MUST have 16 MAC addresses reserved for it, and the last
+      nibble is used to represent the WLAN ID.
+
+   Beacon Period:   This attribute specifies the number of TUs that a
+      station uses for scheduling Beacon transmissions.  This value is
+      transmitted in Beacon and Probe Response frames.
+
+   DTIM Period:   This attribute specifies the number of Beacon
+      intervals that elapses between transmission of Beacons frames
+      containing a TIM element whose DTIM Count field is 0.  This value
+      is transmitted in the DTIM Period field of Beacon frames.
+
+   Country Code:   This attribute identifies the country in which the
+      station is operating.  The first two octets of this string is the
+      two-character country code as described in document ISO/IEC 3166-
+      1.  The third octet MUST be one of the following:
+
+   1. an ASCII space character, if the regulations under which the
+      station is operating encompass all environments in the country,
+
+   2. an ASCII 'O' character, if the regulations under which the station
+      is operating are for an outdoor environment only, or
+
+
+
+Calhoun, et al.                 Historic                      [Page 106]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   3. an ASCII 'I' character, if the regulations under which the station
+      is operating are for an indoor environment only.
+
+   Number of BSSIDs:   This attribute contains the maximum number of
+      BSSIDs supported by the WTP.  This value restricts the number of
+      logical networks supported by the WTP.
+
+11.9.2.  IEEE 802.11 Rate Set
+
+   The Rate Set message element value is sent by the AC and contains the
+   supported operational rates.  It contains the following fields:
+
+        0                   1                   2                   3
+        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |                   Rate Set                    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   16 for IEEE 802.11 Rate Set
+
+   Length:   4
+
+   Radio ID:   An 8-bit value representing the radio to configure.
+
+   Rate Set:   The AC generates the Rate Set that the WTP is to include
+      in its Beacon and Probe messages.
+
+11.9.3.  IEEE 802.11 Multi-Domain Capability
+
+   The Multi-Domain Capability message element is used by the AC to
+   inform the WTP of regulatory limits.  The value contains the
+   following fields:
+
+        0                   1                   2                   3
+        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |    Reserved   |        First Channel #        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |       Number of Channels      |       Max Tx Power Level      |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   10 for IEEE 802.11 Multi-Domain Capability
+
+   Length:   8
+
+   Radio ID:   An 8-bit value representing the radio to configure.
+
+   Reserved:   MUST be set to zero
+
+
+
+Calhoun, et al.                 Historic                      [Page 107]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   First Channel #:   This attribute indicates the value of the lowest
+      channel number in the subband for the associated domain country
+      string.
+
+   Number of Channels:   This attribute indicates the value of the total
+      number of channels allowed in the subband for the associated
+      domain country string.
+
+   Max Tx Power Level:   This attribute indicates the maximum transmit
+      power, in dBm, allowed in the subband for the associated domain
+      country string.
+
+11.9.4.  IEEE 802.11 MAC Operation
+
+   The MAC Operation message element is sent by the AC to set the 802.11
+   MAC parameters on the WTP.  The value contains the following fields:
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |    Reserved   |         RTS Threshold         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  Short Retry  |  Long Retry   |    Fragmentation Threshold    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       Tx MSDU Lifetime                        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       Rx MSDU Lifetime                        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   11 for IEEE 802.11 MAC Operation
+
+   Length:   16
+
+   Radio ID:   An 8-bit value representing the radio to configure.
+
+   Reserved:   MUST be set to zero
+
+   RTS Threshold:   This attribute indicates the number of octets in a
+      Management Protocol Data Unit (MPDU), below which an RTS/CTS
+      (clear to send) handshake MUST NOT be performed.  An RTS/CTS
+      handshake MUST be performed at the beginning of any frame exchange
+      sequence where the MPDU is of type Data or Management, the MPDU
+      has an individual address in the Address1 field, and the length of
+      the MPDU is greater than this threshold.  Setting this attribute
+      to be larger than the maximum MAC Service Data Unit (MSDU) size
+      MUST have the effect of turning off the RTS/CTS handshake for
+      frames of Data or Management type transmitted by this Station
+      (STA).  Setting this attribute to zero MUST have the effect of
+
+
+
+Calhoun, et al.                 Historic                      [Page 108]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+      turning on the RTS/CTS handshake for all frames of Data or
+      Management type transmitted by this STA.  The default value of
+      this attribute MUST be 2347.
+
+   Short Retry:   This attribute indicates the maximum number of
+      transmission attempts of a frame, the length of which is less than
+      or equal to RTSThreshold, that MUST be made before a failure
+      condition is indicated.  The default value of this attribute MUST
+      be 7.
+
+   Long Retry:   This attribute indicates the maximum number of
+      transmission attempts of a frame, the length of which is greater
+      than dot11RTSThreshold, that MUST be made before a failure
+      condition is indicated.  The default value of this attribute MUST
+      be 4.
+
+   Fragmentation Threshold:   This attribute specifies the current
+      maximum size, in octets, of the MPDU that MAY be delivered to the
+      PHY.  An MSDU MUST be broken into fragments if its size exceeds
+      the value of this attribute after adding MAC headers and trailers.
+      An MSDU or MAC Management Protocol Data Unit (MMPDU) MUST be
+      fragmented when the resulting frame has an individual address in
+      the Address1 field, and the length of the frame is larger than
+      this threshold.  The default value for this attribute MUST be the
+      lesser of 2346 or the aMPDUMaxLength of the attached PHY and MUST
+      never exceed the lesser of 2346 or the aMPDUMaxLength of the
+      attached PHY.  The value of this attribute MUST never be less than
+      256.
+
+   Tx MSDU Lifetime:   This attribute specifies the elapsed time in TU,
+      after the initial transmission of an MSDU, after which, further
+      attempts to transmit the MSDU MUST be terminated.  The default
+      value of this attribute MUST be 512.
+
+   Rx MSDU Lifetime:   This attribute specifies the elapsed time, in TU,
+      after the initial reception of a fragmented MMPDU or MSDU, after
+      which, further attempts to reassemble the MMPDU or MSDU MUST be
+      terminated.  The default value MUST be 512.
+
+11.9.5.  IEEE 802.11 Tx Power
+
+   The Tx Power message element value is bi-directional.  When sent by
+   the WTP, it contains the current power level of the radio in
+   question.  When sent by the AC, it contains the power level to which
+   the WTP MUST adhere:
+
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 109]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |    Reserved   |        Current Tx Power       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   12 for IEEE 802.11 Tx Power
+
+   Length:   4
+
+   Radio ID:   An 8-bit value representing the radio to configure.
+
+   Reserved:   MUST be set to zero
+
+   Current Tx Power:   This attribute contains the transmit output power
+      in mW.
+
+11.9.6.  IEEE 802.11 Tx Power Level
+
+   The Tx Power Level message element is sent by the WTP and contains
+   the different power levels supported.  The value contains the
+   following fields:
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |   Num Levels  |        Power Level [n]        |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   13 for IEEE 802.11 Tx Power Level
+
+   Length:   >= 4
+
+   Radio ID:   An 8-bit value representing the radio to configure.
+
+   Num Levels:   The number of power level attributes.
+
+   Power Level:   Each power level fields contains a supported power
+      level, in mW.
+
+11.9.7.  IEEE 802.11 Direct Sequence Control
+
+   The Direct Sequence Control message element is a bi-directional
+   element.  When sent by the WTP, it contains the current state.  When
+   sent by the AC, the WTP MUST adhere to the values.  This element is
+   only used for 802.11b radios.  The value has the following fields.
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 110]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |    Reserved   | Current Chan  |  Current CCA  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                    Energy Detect Threshold                    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   14 for IEEE 802.11 Direct Sequence Control
+
+   Length:   8
+
+   Radio ID:   An 8-bit value representing the radio to configure.
+
+   Reserved:   MUST be set to zero
+
+   Current Channel:   This attribute contains the current operating
+      frequency channel of the Direct Sequence Spread Spectrum (DSSS)
+      PHY.
+
+   Current CCA:   The current Controlled Channel Access (CCA) method in
+      operation.  Valid values are:
+
+      1 - energy detect only (edonly)
+
+      2 - carrier sense only (csonly)
+
+      4 - carrier sense and energy detect (edandcs)
+
+      8 - carrier sense with timer (cswithtimer)
+
+      16 - high-rate carrier sense and energy detect (hrcsanded)
+
+   Energy Detect Threshold:   The current Energy Detect Threshold being
+      used by the DSSS PHY.
+
+11.9.8.  IEEE 802.11 OFDM Control
+
+   The Orthogonal Frequency Division Multiplexing (OFDM) Control message
+   element is a bi-directional element.  When sent by the WTP, it
+   contains the current state.  When sent by the AC, the WTP MUST adhere
+   to the values.  This element is only used for 802.11a radios.  The
+   value contains the following fields:
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 111]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |    Reserved   | Current Chan  |  Band Support |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                         TI Threshold                          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   15 for IEEE 802.11 OFDM Control
+
+   Length:   8
+
+   Radio ID:   An 8-bit value representing the radio to configure.
+
+   Reserved:   MUST be set to zero
+
+   Current Channel:   This attribute contains the current operating
+      frequency channel of the OFDM PHY.
+
+   Band Supported:   The capability of the OFDM PHY implementation to
+      operate in the three U-NII bands.  Coded as an integer value of a
+      3-bit field as follows:
+
+      Bit 0 -  capable of operating in the lower (5.15-5.25 GHz) U-NII
+               band
+
+      Bit 1 -  capable of operating in the middle (5.25-5.35 GHz) U-NII
+               band
+
+      Bit 2 -  capable of operating in the upper (5.725-5.825 GHz) U-NII
+               band
+
+      For example, for an implementation capable of operating in the
+      lower and mid bands, this attribute would take the value.
+
+   TI Threshold:   The threshold being used to detect a busy medium
+      (frequency).  CCA MUST report a busy medium upon detecting the
+      RSSI above this threshold.
+
+11.9.9.  IEEE 802.11 Antenna
+
+   The Antenna message element is communicated by the WTP to the AC to
+   provide information on the antennas available.  The AC MAY use this
+   element to reconfigure the WTP's antennas.  The value contains the
+   following fields:
+
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 112]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |   Diversity   |    Combiner   |  Antenna Cnt  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                    Antenna Selection [0..N]                   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   41 for IEEE 802.11 Antenna
+
+   Length:   >= 8
+
+   Radio ID:   An 8-bit value representing the radio to configure.
+
+   Diversity:   An 8-bit value specifying whether the antenna is to
+      provide receive diversity.  The following values are supported:
+
+      0 -  Disabled
+
+      1 -  Enabled (may only be true if the antenna can be used as a
+           receive antenna)
+
+   Combiner:   An 8-bit value specifying the combiner selection.  The
+      following values are supported:
+
+      1 -  Sectorized (Left)
+
+      2 -  Sectorized (Right)
+
+      3 -  Omni
+
+      4 -  Mimo
+
+   Antenna Count:   An 8-bit value specifying the number of Antenna
+      Selection fields.
+
+   Antenna Selection:   One 8-bit antenna configuration value per
+      antenna in the WTP.  The following values are supported:
+
+      1 -  Internal Antenna
+
+      2 -  External Antenna
+
+11.9.10.  IEEE 802.11 Supported Rates
+
+   The Supported Rates message element is sent by the WTP to indicate
+   the rates that it supports.  The value contains the following fields:
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 113]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    Radio ID   |                 Supported Rates               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   16 for IEEE 802.11 Supported Rates
+
+   Length:   4
+
+   Radio ID:   An 8-bit value representing the radio.
+
+   Supported Rates:   The WTP includes the Supported Rates that its
+      hardware supports.  The format is identical to the Rate Set
+      message element.
+
+11.9.11.  IEEE 802.11 CFP Status
+
+   The CFP Status message element is sent to provide the CF Polling
+   configuration.
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Radio ID    |    Status     |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   48 for IEEE 802.11 CFP Status
+
+   Length:   2
+
+   Radio ID:   The Radio Identifier, typically refers to some interface
+      index on the WTP.
+
+   Status:   An 8-bit Boolean containing the status of the CF Polling
+      feature.  A value of zero disables CFP Status, while a value of
+      one enables it.
+
+11.9.12.  IEEE 802.11 WTP Mode and Type
+
+   The WTP Mode and Type message element is used to configure a WTP to
+   operate in a specific mode.
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     Mode      |     Type      |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+
+
+Calhoun, et al.                 Historic                      [Page 114]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Type:   54 for IEEE 802.11 WTP Mode and Type
+
+   Length:   2
+
+   Mode:   An 8-bit value describing the type of information being sent.
+      The following values are supported:
+
+      0 -  Split MAC
+
+      2 -  Local MAC
+
+   Type:   The type field is not currently used.
+
+11.9.13.  IEEE 802.11 Broadcast Probe Mode
+
+   The Broadcast Probe Mode message element indicates whether a WTP will
+   respond to NULL SSID Probe requests.  Since broadcast NULL Probes are
+   not sent to a specific BSSID, the WTP cannot know which SSID the
+   sending station is querying.  Therefore, this behavior must be global
+   to the WTP.
+
+       0
+       0 1 2 3 4 5 6 7
+      +-+-+-+-+-+-+-+-+
+      |    Status     |
+      +-+-+-+-+-+-+-+-+
+
+   Type:   51 for IEEE 802.11 Broadcast Probe Mode
+
+   Length:   1
+
+   Status:   An 8-bit Boolean indicating the status of whether a WTP
+      shall respond to a NULL SSID Probe request.  A value of zero
+      disables the NULL SSID Probe response, while a value of one
+      enables it.
+
+11.9.14.  IEEE 802.11 WTP Quality of Service
+
+   The WTP Quality of Service message element value is sent by the AC to
+   the WTP to communicate quality-of-service configuration information.
+
+       0                   1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Radio ID    |  Tag Packets  |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   57 for IEEE 802.11 WTP Quality of Service
+
+
+
+Calhoun, et al.                 Historic                      [Page 115]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Length:   12
+
+   Radio ID:   The Radio Identifier, typically refers to some interface
+      index on the WTP.
+
+   Tag Packets:   A value indicating whether LWAPP packets should be
+      tagged for QoS purposes.  The following values are currently
+      supported:
+
+      0 -  Untagged
+
+      1 -  802.1P
+
+      2 -  DSCP
+
+      Immediately following the above header is the following data
+      structure.  This data structure will be repeated five times, once
+      for every QoS profile.  The order of the QoS profiles is Uranium,
+      Platinum, Gold, Silver, and Bronze.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  Queue Depth  |             CWMin             |     CWMax     |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     CWMax     |     AIFS      |              CBR              |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Dot1P Tag   |   DSCP Tag    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Queue Depth:   The number of packets that can be on the specific QoS
+      transmit queue at any given time.
+
+   CWMin:   The Contention Window minimum value for the QoS transmit
+      queue.
+
+   CWMax:   The Contention Window maximum value for the QoS transmit
+      queue.
+
+   AIFS:   The Arbitration Inter Frame Spacing to use for the QoS
+      transmit queue.
+
+   CBR:   The Constant Bit Rate (CBR) value to observe for the QoS
+      transmit queue.
+
+   Dot1P Tag:   The 802.1P precedence value to use if packets are to be
+      802.1P tagged.
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 116]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   DSCP Tag:   The DSCP label to use if packets are to be DSCP tagged.
+
+11.9.15.  IEEE 802.11 MIC Error Report From Mobile
+
+   The MIC Error Report From Mobile message element is sent by an AC to
+   a WTP when it receives a MIC failure notification via the Error bit
+   in the EAP over LAN (EAPOL)-Key frame.
+
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       Client MAC Address                      |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      Client MAC Address       |             BSSID             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                             BSSID                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Radio ID    |    WLAN ID    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+   Type:   79 for IEEE 802.11 MIC Error Report From Mobile
+
+   Length:   14
+
+   Client MAC Address:   The Client MAC address of the station reporting
+      the MIC failure.
+
+   BSSID:   The BSSID on which the MIC failure is being reported.
+
+   Radio ID:   The Radio Identifier, typically refers to some interface
+      index on the WTP.
+
+   WLAN ID:   The WLAN ID on which the MIC failure is being reported.
+
+11.10.  IEEE 802.11 Message Element Values
+
+   This section lists IEEE 802.11-specific values for any generic LWAPP
+   message elements that include fields whose values are technology-
+   specific.
+
+   IEEE 802.11 uses the following values:
+
+   4 - Encrypt AES-CCMP 128:   WTP supports AES-CCMP, as defined in [7].
+
+   5 - Encrypt TKIP-MIC:   WTP supports TKIP and Michael, as defined in
+       [16].
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 117]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+12.  LWAPP Protocol Timers
+
+   A WTP or AC that implements LWAPP discovery MUST implement the
+   following timers.
+
+12.1.  MaxDiscoveryInterval
+
+   The maximum time allowed between sending Discovery Requests from the
+   interface, in seconds.  Must be no less than 2 seconds and no greater
+   than 180 seconds.
+
+   Default: 20 seconds.
+
+12.2.  SilentInterval
+
+   The minimum time, in seconds, a WTP MUST wait after failing to
+   receive any responses to its Discovery Requests, before it MAY again
+   send Discovery Requests.
+
+   Default: 30
+
+12.3.  NeighborDeadInterval
+
+   The minimum time, in seconds, a WTP MUST wait without having received
+   Echo Responses to its Echo Requests, before the destination for the
+   Echo Request may be considered dead.  Must be no less than
+   2*EchoInterval seconds and no greater than 240 seconds.
+
+   Default: 60
+
+12.4.  EchoInterval
+
+   The minimum time, in seconds, between sending Echo Requests to the AC
+   with which the WTP has joined.
+
+   Default: 30
+
+12.5.  DiscoveryInterval
+
+   The minimum time, in seconds, that a WTP MUST wait after receiving a
+   Discovery Response, before sending a Join Request.
+
+   Default: 5
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 118]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+12.6.  RetransmitInterval
+
+   The minimum time, in seconds, that a non-acknowledged LWAPP packet
+   will be retransmitted.
+
+   Default: 3
+
+12.7.  ResponseTimeout
+
+   The minimum time, in seconds, in which an LWAPP Request message must
+   be responded to.
+
+   Default: 1
+
+12.8.  KeyLifetime
+
+   The maximum time, in seconds, that an LWAPP session key is valid.
+
+   Default: 28800
+
+13.  LWAPP Protocol Variables
+
+   A WTP or AC that implements LWAPP discovery MUST allow for the
+   following variables to be configured by system management; default
+   values are specified so as to make it unnecessary to configure any of
+   these variables in many cases.
+
+13.1.  MaxDiscoveries
+
+   The maximum number of Discovery Requests that will be sent after a
+   WTP boots.
+
+   Default: 10
+
+13.2.  DiscoveryCount
+
+   The number of discoveries transmitted by a WTP to a single AC.  This
+   is a monotonically increasing counter.
+
+13.3.  RetransmitCount
+
+   The number of retransmissions for a given LWAPP packet.  This is a
+   monotonically increasing counter.
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 119]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+13.4.  MaxRetransmit
+
+   The maximum number of retransmissions for a given LWAPP packet before
+   the link layer considers the peer dead.
+
+   Default: 5
+
+14.  NAT Considerations
+
+   There are two specific situations where a NAT system may be used in
+   conjunction with LWAPP.  The first consists of a configuration where
+   the WTP is behind a NAT system.  Given that all communication is
+   initiated by the WTP, and all communication is performed over IP
+   using a single UDP port, the protocol easily traverses NAT systems in
+   this configuration.
+
+   The second configuration is one where the AC sits behind a NAT, and
+   there are two main issues that exist in this situation.  First, an AC
+   communicates its interfaces and associated WTP load on these
+   interfaces, through the WTP Manager Control IP Address.  This message
+   element is currently mandatory, and if NAT compliance became an
+   issue, it would be possible to either:
+
+   1. make the WTP Manager Control IP Address optional, allowing the WTP
+      to simply use the known IP address.  However, note that this
+      approach would eliminate the ability to perform load balancing of
+      WTP across ACs, and therefore is not the recommended approach.
+
+   2. allow an AC to be able to configure a NAT'ed address for every
+      associated AC that would generally be communicated in the WTP
+      Manager Control IP Address message element.
+
+   3. require that if a WTP determines that the AC List message element
+      consists of a set of IP addresses that are different from the AC's
+      IP address it is currently communicating with, then assume that
+      NAT is being enforced, and require that the WTP communicate with
+      the original AC's IP address (and ignore the WTP Manager Control
+      IP Address message element(s)).
+
+   Another issue related to having an AC behind a NAT system is LWAPP's
+   support for the CAPWAP Objective to allow the control and data plane
+   to be separated.  In order to support this requirement, the LWAPP
+   protocol defines the WTP Manager Data IP Address message element,
+   which allows the AC to inform the WTP that the LWAPP data frames are
+   to be forwarded to a separate IP address.  This feature MUST be
+   disabled when an AC is behind a NAT.  However, there is no easy way
+   to provide some default mechanism that satisfies both the data/
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 120]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   control separation and NAT objectives, as they directly conflict with
+   each other.  As a consequence, user intervention will be required to
+   support such networks.
+
+   LWAPP has a feature that allows for all of the AC's identities
+   supporting a group of WTPs to be communicated through the AC List
+   message element.  This feature must be disabled when the AC is behind
+   a NAT and the IP address that is embedded would be invalid.
+
+   The LWAPP protocol has a feature that allows an AC to configure a
+   static IP address on a WTP.  The WTP Static IP Address Information
+   message element provides such a function; however, this feature
+   SHOULD NOT be used in NAT'ed environments, unless the administrator
+   is familiar with the internal IP addressing scheme within the WTP's
+   private network, and does not rely on the public address seen by the
+   AC.
+
+   When a WTP detects the duplicate address condition, it generates a
+   message to the AC, which includes the Duplicate IP Address message
+   element.  Once again, it is important to note that the IP address
+   embedded within this message element would be different from the
+   public IP address seen by the AC.
+
+15.  Security Considerations
+
+   LWAPP uses either an authenticated key exchange or key agreement
+   mechanism to ensure peer authenticity and establish fresh session
+   keys to protect the LWAPP communications.
+
+   The LWAPP protocol defines a join phase, which allows a WTP to bind a
+   session with an AC.  During this process, a session key is mutually
+   derived, and secured either through an X.509 certificate or a pre-
+   shared key.  The resulting key exchange generates an encryption
+   session key, which is used to encrypt the LWAPP control packets, and
+   a key derivation key.
+
+   During the established secure communication, the WTP and AC may rekey
+   using the key update process, which is identical to the join phase,
+   meaning the session keys are mutually derived.  However, the exchange
+   described for pre-shared session keys is always used for the key
+   update, with the pre-shared key set to the derivation key created
+   either during the join, or the last key update if one has occurred.
+   The key update results in a new derivation key, which is used in the
+   next key update, as well as an encryption session key to encrypt the
+   LWAPP control packets.
+
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 121]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   Replay protection of the Join Request is handled through an exchange
+   of nonces during the join (or key update) phase.  The Join Request
+   includes an XNonce, which is included in the AC's authenticated Join
+   Reply's encrypted ANonce message element, allowing for the two
+   messages to be bound.  Upon receipt of the Join Reply, the WTP
+   generates the WNonce, and generates a set of session keys using a KDF
+   function.  One of these keys is used to MIC the Join ACK.  The AC
+   responds with a Join Confirm, which must also include a MIC, and
+   therefore be capable of deriving the same set of session keys.
+
+   In both the X.509 certificate and pre-shared key modes, an
+   initialization vector is created through the above mentioned KDF
+   function.  The IV and the KDF created encryption key are used to
+   encrypt the LWAPP control frames.
+
+   Given that authentication in the Join exchange does not occur until
+   the WTP transmits the Join ACK message, it is crucial that an AC not
+   delete any state for a WTP it is servicing until an authentication
+   Join ACK has been received.  Otherwise, a potential Denial-of-Service
+   attack exists, whereby sending a spoofed Join Request for a valid WTP
+   would cause the AC to reset the WTP's connection.
+
+   It is important to note that Perfect Forward Secrecy is not a
+   requirement for the LWAPP protocol.
+
+   Note that the LWAPP protocol does not add any new vulnerabilities to
+   802.11 infrastructure that makes use of WEP for encryption purposes.
+   However, implementors SHOULD discourage the use of WEP to allow the
+   market to move towards technically sound cryptographic solutions,
+   such as 802.11i.
+
+15.1.  Certificate-Based Session Key Establishment
+
+   LWAPP uses public key cryptography to ensure trust between the WTP
+   and the AC.  One question that periodically arises is why the Join
+   Request is not signed.  Signing this request would not be optimal for
+   the following reasons:
+
+   1. The Join Request is replayable, so a signature doesn't provide
+      much protection unless the switches keep track of all previous
+      Join Requests from a given WTP.
+
+   2. Replay detection is handled during the Join Reply and Join ACK
+      messages.
+
+   3. A signed Join Request provides a potential Denial-of-Service
+      attack on the AC, which would have to authenticate each
+      (potentially malicious) message.
+
+
+
+Calhoun, et al.                 Historic                      [Page 122]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   The WTP-Certificate that is included in the Join Request MUST be
+   validated by the AC.  It is also good practice that the AC perform
+   some form of authorization, ensuring that the WTP in question is
+   allowed to establish an LWAPP session with it.
+
+15.2.  PSK-Based Session Key Establishment
+
+   Use of a fixed shared secret of limited entropy (for example, a PSK
+   that is relatively short, or was chosen by a human and thus may
+   contain less entropy than its length would imply) may allow an
+   attacker to perform a brute-force or dictionary attack to recover the
+   secret.
+
+   It is RECOMMENDED that implementations that allow the administrator
+   to manually configure the PSK also provide a functionality for
+   generating a new random PSK, taking RFC 1750 [4] into account.
+
+   Since the key generation does not expose the nonces in plaintext,
+   there are no practical passive attacks possible.
+
+16.  Acknowledgements
+
+   The authors wish to thank Michael Vakulenko for contributing text
+   that describes how LWAPP can be used over a Layer 3 (IP) network.
+
+   The authors would also like to thanks Russ Housley and Charles Clancy
+   for their assistance in providing a security review of the LWAPP
+   specification.  Charles' review can be found in [12].
+
+17.  References
+
+17.1.  Normative References
+
+   [1]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
+         Levels", BCP 14, RFC 2119, March 1997.
+
+   [2]   National Institute of Standards and Technology, "Advanced
+         Encryption Standard (AES)", FIPS PUB 197, November 2001,
+         <http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf>.
+
+   [3]   Whiting, D., Housley, R., and N. Ferguson, "Counter with CBC-
+         MAC (CCM)", RFC 3610, September 2003.
+
+   [4]   Eastlake, D., 3rd, Schiller, J., and S. Crocker, "Randomness
+         Requirements for Security", BCP 106, RFC 4086, June 2005.
+
+   [5]   Manner, J., Ed., and M. Kojo, Ed., "Mobility Related
+         Terminology", RFC 3753, June 2004.
+
+
+
+Calhoun, et al.                 Historic                      [Page 123]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+   [6]   "Information technology - Telecommunications and information
+         exchange between systems - Local and metropolitan area networks
+         - Specific requirements - Part 11: Wireless LAN Medium Access
+         Control (MAC) and Physical Layer (PHY) specifications", IEEE
+         Standard 802.11, 2007,
+         <http://standards.ieee.org/getieee802/download/802.11-2007.pdf>
+
+   [7]   "Information technology - Telecommunications and information
+         exchange between systems - Local and metropolitan area networks
+         - Specific requirements - Part 11: Wireless LAN Medium Access
+         Control (MAC) and Physical Layer (PHY) specifications Amendment
+         6: Medium Access Control (MAC) Security Enhancements", IEEE
+         Standard 802.11i, July 2004,
+         http://standards.ieee.org/getieee802/download/802.11i-2004.pdf
+
+   [8]   Clark, D., "IP datagram reassembly algorithms", RFC 815, July
+         1982.
+
+   [9]   Schaad, J. and R. Housley, "Advanced Encryption Standard (AES)
+         Key Wrap Algorithm", RFC 3394, September 2002.
+
+   [10]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley,
+         R., and W. Polk, "Internet X.509 Public Key Infrastructure
+         Certificate and Certificate Revocation List (CRL) Profile", RFC
+         5280, May 2008.
+
+   [11]  "Netscape-Defined Certificate Extensions",
+         <http://www.redhat.com/docs/manuals/cert-
+         system/admin/7.1/app_ext.html#35336>.
+
+   [12]  Clancy, C., "Security Review of the Light-Weight Access Point
+         Protocol", May 2005,
+         <http://www.cs.umd.edu/~clancy/docs/lwapp-review.pdf>.
+
+17.2.  Informative References
+
+   [13]  Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced by
+         an On-line Database", RFC 3232, January 2002.
+
+   [14]   Kent, S. and K. Seo, "Security Architecture for the Internet
+         Protocol", RFC 4301, December 2005.
+
+   [15]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-Hashing
+         for Message Authentication", RFC 2104, February 1997.
+
+   [16]  "WiFi Protected Access (WPA) rev 1.6", April 2003.
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 124]
+
+RFC 5412            Lightweight Access Point Protocol      February 2010
+
+
+Authors' Addresses
+
+   Pat R. Calhoun
+   Cisco Systems, Inc.
+   170 West Tasman Drive
+   San Jose, CA  95134
+   Phone: +1 408-853-5269
+   EMail: pcalhoun@cisco.com
+
+   Rohit Suri
+   Cisco Systems, Inc.
+   170 West Tasman Drive
+   San Jose, CA  95134
+   Phone: +1 408-853-5548
+   EMail: rsuri@cisco.com
+
+   Nancy Cam-Winget
+   Cisco Systems, Inc.
+   170 West Tasman Drive
+   San Jose, CA  95134
+   Phone: +1 408-853-0532
+   EMail: ncamwing@cisco.com
+
+   Scott Kelly
+   EMail: scott@hyperthought.com
+
+
+   Michael Glenn Williams
+   GWhiz Arts & Sciences
+   1560 Newbury Road, Suite 1-204
+   Newbury Park, CA 91320
+   Phone: +1 805-499-1994
+   EMail: gwhiz@gwhiz.com
+
+
+   Sue Hares
+   Phone: +1 734-604-0332
+   EMail: shares@ndzh.com
+
+   Bob O'Hara
+   EMail: bob.ohara@computer.org
+
+
+
+
+
+
+
+
+
+
+Calhoun, et al.                 Historic                      [Page 125]
+