path: root/doc/rfc/rfc5950.txt

Internet Engineering Task Force (IETF)                 S. Mansfield, Ed.
Request for Comments: 5950                                  E. Gray, Ed.
Category: Informational                                         Ericsson
ISSN: 2070-1721                                              K. Lam, Ed.
                                                          Alcatel-Lucent
                                                          September 2010


     Network Management Framework for MPLS-based Transport Networks

Abstract

   This document provides the network management framework for the
   Transport Profile for Multi-Protocol Label Switching (MPLS-TP).

   This framework relies on the management terminology from the ITU-T to
   describe the management architecture that could be used for an MPLS-
   TP management network.

   The management of the MPLS-TP network could be based on multi-tiered
   distributed management systems.  This document provides a description
   of the network and element management architectures that could be
   applied and also describes heuristics associated with fault,
   configuration, and performance aspects of the management system.

   This document is a product of a joint Internet Engineering Task Force
   (IETF) / International Telecommunication Union Telecommunication
   Standardization Sector (ITU-T) effort to include an MPLS Transport
   Profile within the IETF MPLS and PWE3 architectures to support the
   capabilities and functionalities of a packet transport network.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   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/rfc5950.





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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.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Management Architecture  . . . . . . . . . . . . . . . . . . .  5
     2.1.  Network Management Architecture  . . . . . . . . . . . . .  5
     2.2.  Element Management Architecture  . . . . . . . . . . . . .  6
     2.3.  Standard Management Interfaces . . . . . . . . . . . . . . 10
     2.4.  Management- and Control-Specific Terminology . . . . . . . 11
     2.5.  Management Channel . . . . . . . . . . . . . . . . . . . . 11
   3.  Fault Management . . . . . . . . . . . . . . . . . . . . . . . 13
     3.1.  Supervision  . . . . . . . . . . . . . . . . . . . . . . . 13
     3.2.  Validation . . . . . . . . . . . . . . . . . . . . . . . . 13
     3.3.  Alarm Handling . . . . . . . . . . . . . . . . . . . . . . 13
   4.  Configuration Management . . . . . . . . . . . . . . . . . . . 13
     4.1.  LSP Ownership Handover . . . . . . . . . . . . . . . . . . 14
   5.  Performance Management . . . . . . . . . . . . . . . . . . . . 15
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 16
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 17














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1.  Introduction

   This document provides the network management framework for the
   Transport Profile for Multi-Protocol Label Switching (MPLS-TP).
   Requirements for network management in an MPLS-TP network are
   documented in "Network Management Requirements for MPLS-based
   Transport Networks" [3], and this document explains how network
   elements and networks that support MPLS-TP can be managed using
   solutions that satisfy those requirements.  The relationship between
   Operations, Administration, and Maintenance (OAM), management, and
   other framework documents is described in the MPLS-TP framework [4]
   document.

   This document is a product of a joint Internet Engineering Task Force
   (IETF) / International Telecommunication Union Telecommunication
   Standardization Sector (ITU-T) effort to include an MPLS Transport
   Profile within the IETF MPLS and PWE3 architectures to support the
   capabilities and functionalities of a packet transport network.

1.1.  Terminology

   This framework relies on the management terminology from the ITU-T to
   describe the management architecture that could be used for an
   MPLS-TP management network.  The terminology listed below are taken
   from/based on the definitions found in ITU-T G.7710 [6], ITU-T G.7712
   [7], and ITU-T M.3013 [13].

   o  Communication Channel (CCh): A logical channel between network
      elements (NEs) that can be used in (for example) management plane
      applications or control plane applications.  For MPLS-TP, the
      physical channel supporting the CCh is the MPLS-TP Management
      Communication Channel (MCC).

   o  Data Communication Network (DCN): A network that supports Layer 1
      (physical), Layer 2 (data-link), and Layer 3 (network)
      functionality for distributed management communications related to
      the management plane, for distributed signaling communications
      related to the control plane, and other operations communications
      (e.g., order-wire/voice communications, software downloads, etc.).
      See ITU-T G.7712 [7].

   o  Equipment Management Function (EMF): The management functions
      within an NE.  See ITU-T G.7710 [6].

   o  Local Craft Terminal (LCT): An out-of-band device that connects to
      an NE for management purposes.  See ITU-T G.7710 [6].





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   o  Label Switched Path (LSP): An MPLS-TP LSP is an LSP that uses a
      subset of the capabilities of an MPLS LSP in order to meet the
      requirements of an MPLS transport network as described in the
      MPLS-TP framework [4].

   o  Management Application Function (MAF): An application process that
      participates in system management.  See ITU-T G.7710 [6].

   o  Management Communication Channel (MCC): A CCh dedicated for
      management plane communications.  See ITU-T G.7712 [7].

   o  Message Communication Function (MCF): The communications process
      that performs functions such as information interchange and relay.
      See ITU-T M.3013 [13].

   o  Management Communication Network (MCN): A DCN supporting
      management plane communication is referred to as a Management
      Communication Network (MCN).  See ITU-T G.7712 [7].

   o  MPLS-TP NE: A network element (NE) that supports MPLS-TP
      functions.  Another term that is used for a network element is
      node.  In terms of this document, the term node is equivalent to
      NE.

   o  MPLS-TP network: A network in which MPLS-TP NEs are deployed.

   o  Network Element Function (NEF): The set of functions necessary to
      manage a network element.  See ITU-T M.3010 [11].

   o  Operations, Administration, and Maintenance (OAM): For the MPLS-TP
      effort the term OAM means the set of tools that consist of
      "operation" activities that are undertaken to keep the network up
      and running, "administration" activities that keep track of
      resources in the network and how they are used, and "maintenance"
      activities that facilitate repairs and upgrades.  For a complete
      expansion of the acronym, see "The OAM Acronym Soup" [15].

   o  Operations System (OS): A system that performs the functions that
      support processing of information related to operations,
      administration, maintenance, and provisioning (OAM&P) (see "The
      OAM Acronym Soup" [15]) for the networks, including surveillance
      and testing functions to support customer access maintenance.  See
      ITU-T M.3010 [11].

   o  Signaling Communication Network (SCN): A DCN supporting control
      plane communication is referred to as a Signaling Communication
      Network (SCN).  See ITU-T G.7712 [7].




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   o  Signaling Communication Channel (SCC): A CCh dedicated for control
      plane communications.  The SCC may be used for GMPLS/ASON
      signaling and/or other control plane messages (e.g., routing
      messages).  See ITU-T G.7712 [7].

2.  Management Architecture

   The management of the MPLS-TP network could be based on a multi-
   tiered distributed management systems, for example as described in
   ITU-T M.3010 [11] and ITU-T M.3060/Y.2401 [12].  Each tier provides a
   predefined level of network management capabilities.  The lowest tier
   of this organization model includes the MPLS-TP network element that
   provides the transport service and the Operations System (OS) at the
   Element Management Level.  The Management Application Function (MAF)
   within the NEs and OSs provides the management support.  The MAF at
   each entity can include agents only, managers only, or both agents
   and managers.  The MAF that includes managers is capable of managing
   an agent included in other MAF.

   The management communication to peer NEs and/or OSs is provided via
   the Message Communication Function (MCF) within each entity (e.g., NE
   and OS).  The user can access the management of the MPLS-TP transport
   network via a Local Craft Terminal (LCT) attached to the NE or via a
   Work Station (WS) attached to the OS.

2.1.  Network Management Architecture

   A transport Management Network (MN) may consist of several transport-
   technology-specific Management Networks.  Management network
   partitioning (Figure 1) below (based on ITU-T G.7710 [6]) shows the
   management network partitioning.  Notation used in G.7710 for a
   transport-technology-specific MN is x.MN, where x is the transport-
   specific technology.  An MPLS-TP-specific MN is abbreviated as MT.MN.
   Where there is no ambiguity, we will use "MN" for an MPLS-TP-specific
   MN.  In the figure below, O.MSN is equivalent to an OTN management
   Subnetwork.















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    ______________________________  _________________________________
   |.-------.-------.----.-------.||.--------.--------.----.--------.|
   |:       :       :    :       :||:        :        :    :        :|
   |:O.MSN-1:O.MSN-2: .. :O.MSN-n:||:MT.MSN-1:MT.MSN-2: .. :MT.MSN-n:|
   |:       :       :    :       :||:        :        :    :        :|
   '-============================-''-===============================-'
                   _______________________________
                  |.-------.-------.-----.-------.|
                  |:       :       :     :       :|
                  |:x.MSN-1:x.MSN-2: ... :x.MSN-n:|
                  |:       :       :     :       :|
                  '-=============================-'

                      Management Network Partitioning

                                 Figure 1

   The management of the MPLS-TP network is separable from the
   management of the other technology-specific networks, and it operates
   independently of any particular client- or server-layer management
   plane.

   An MPLS-TP Management Network (MT.MN) could be partitioned into
   MPLS-TP Management SubNetworks ("MT.MSN" or "MPLS-TP MSN", or just
   "MSN" where usage is unambiguous) for consideration of scalability
   (e.g., geographic or load balancing) or administration (e.g.,
   operation or ownership).

   The MPLS-TP MSN could be connected to other parts of the MN through
   one or more LCTs and/or OSs.  The Message Communication Function
   (MCF) of an MPLS-TP NE initiates/terminates, routes, or otherwise
   processes management messages over CChs or via an external interface.

   Multiple addressable MPLS-TP NEs could be present at a single
   physical location (i.e., site or office).  The inter-site
   communications link between the MPLS-TP NEs will normally be provided
   by the CChs.  Within a particular site, the NEs could communicate via
   an intra-site CCh or via a LAN.

2.2.  Element Management Architecture

   The Equipment Management Function (EMF) of an MPLS-TP NE provides the
   means through which a management system manages the NE.

   The EMF interacts with the NE's transport functions by exchanging
   Management Information (MI) across the Management Point (MP)
   Reference Points.  The EMF may contain a number of functions that




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   provide a data reduction mechanism on the information received across
   the MP Reference Points.

   The EMF includes functions such as Date and Time, FCAPS (Fault,
   Configuration, Accounting, Performance, and Security) management, and
   Control Plane functions.  The EMF provides event message processing,
   data storage, and logging.  The management Agent, a component of the
   EMF, converts internal management information (MI signals) into
   Management Application messages and vice versa.  The Agent responds
   to Management Application messages from the Message Communication
   Function (MCF) by performing the appropriate operations on (for
   example) the Managed Objects in a Management Information Base (MIB),
   as necessary.  The MCF contains communications functions related to
   the world outside of the NE (i.e., Date and Time source, Management
   Plane, Control Plane, Local Craft Terminal, and Local Alarms).

   The Date and Time functions keep track of the NE's date/time, which
   is used by the FCAPS management functions to e.g., time stamp event
   reports.

   Below are diagrams that illustrate the components of the Equipment
   Management Function (EMF) of a Network Element (NE).  The high-level
   decomposition of the Network Element Function (NEF) picture
   (Figure 2) provides the breakdown of the NEF, then the EMF picture
   (Figure 3) provides the details of Equipment Management Function, and
   finally the Message Communication Function (MCF) picture (Figure 4)
   details the MCF.
























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    ____________________________________________________
   |            Network Element Function (NEF)          |
   | _________________________________________          |
   ||                                         |         |
   ||    Transport Plane Atomic Functions     |         |
   ||_________________________________________|         |
   |                     |                              |
   |                     | Management                   |
   |                     | Information                  |
   |  ___________________|_________________             |
   | |                    (from date/time)<-----------+ |
   | | Equipment                           |          | |
   | | Management     (to/from management)<--------+  | |
   | | Function                            |       |  | |
   | | (EMF)             (to/from control)<-----+  |  | |
   | |                                     |    |  |  | |
   | |                    (to local alarm)---+  |  |  | |
   | |_____________________________________| |  |  |  | |
   |                                         |  |  |  | |
   |  +--------------------------------------+  |  |  | |
   |  | +---------------------------------------+  |  | |
   |  | | +----------------------------------------+  | |
   |  | | | +-----------------------------------------+ |external
   |  | | | | Date & Time  _________________            |time
   |  | | | | Interface   | Message         |           |source
   |  | | | +-------------- Communication  <-----------------------
   |  | | |               | Function (MCF)  |           |
   |  | | | Management    |                 |           |management
   |  | | +---------------->                |           |plane
   |  | |   Plane Interface                <---------------------->
   |  | |                 |                 |           |local
   |  | |                 |                 |           |craft
   |  | |   Control Plane |                 |           |terminal
   |  | +------------------>               <---------------------->
   |  |     Interface     |                 |           |control
   |  |                   |                 |           |plane
   |  |     Local Alarm   |                <---------------------->
   |  +-------------------->                |           |
   |        Interface     |                 |           |to local
   |                      |                 |           |alarms
   |                      |_________________--------------------->
   |____________________________________________________|

                      High-Level Decomposition of NEF

                                 Figure 2





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    ______________________________________________________
   |              _______________________________________ |
   |  Equipment  |             Management Application    ||
   |  Management |                Function (MAF)         ||
   |  Function   | _________________                     ||
   |  (EMF)      ||                 |  __________________||
   |  ___________||_______________  | |                  ||
   | |                            | | | Date & Time      ||
   | | Date & Time Functions      | | | Interface        ||<-- 1
   | |____________________________| | |__________________||
   |  ___________||_______________  |  __________________||
   | |                            | | |                  ||
   | | Fault Management           | | | Management       ||
   | |____________________________| | | Plane Interface  ||<-> 2
   |  ___________||_______________  | |__________________||
   | |                            | |                    ||
   | | Configuration Management   | |  __________________||
   | |____________________________| | |                  ||
   |  ___________||_______________  | | Control          ||
   | |                            | | | Plane Interface  ||<-> 3
   | | Account Management         | | |__________________||
   | |____________________________| |                    ||
   |  ___________||_______________  |                    ||
   | |                            | |                    ||
   | | Performance Management     | |                    ||
   | |____________________________| |                    ||
   |  ___________||_______________  |                    ||
   | |                            | |                    ||
   | | Security Management        | |                    ||
   | |____________________________| |                    ||
   |  ___________||_______________  |                    ||
   | |                            | |                    ||
   | | Control Plane Function     | |                    ||
   | |____________________________| |                    ||
   |             ||                 |  __________________||
   |             ||                 | |                  ||
   |             ||                 | | Local Alarm      ||
   |       +----->| Agent           | | Interface        ||--> 4
   |       v     ||_________________| |__________________||
   |   .-===-.   |_______________________________________||
   |   | MIB |                                            |
   |   `-._.-'                                            |
   |______________________________________________________|

                       Equipment Management Function

                                 Figure 3




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                     _________________
                    |                 |
                    |   Message       |
                    | Communication   |
                    | Function (MCF)  |
                    | _______________ |
      Date & Time   ||               || external
   1 <--------------|| Date & Time   ||<--------------
      Information   || Communication || time source
                    ||_______________||
                    |                 |
                    | _______________ |
      Management    ||               || management
      Plane         ||  Management   || plane
   2 <------------->||    Plane      ||<------------->
      Information   || Communication || (e.g. - EMS,
                    ||_______________||  peer NE)
                    |                 |
                    | _______________ | control
      Control Plane ||               || plane
   3 <------------->|| Control Plane ||<------------->
      Information   || Communication || (e.g. - EMS,
                    ||_______________||  peer NE)
                    |        :        |
                    |        :        | local craft
                    |        :        | terminal
                    |        :        |<------------->
                    | _______________ |
      Local Alarm   ||               || to local
   4 -------------->|| Local Alarm   ||-------------->
      Information   || Communication || alarms...
                    ||_______________||
                    |_________________|

                      Message Communication Function

                                 Figure 4

2.3.  Standard Management Interfaces

   The "Network Management Requirements for MPLS-based Transport
   Networks" document [3] places no restriction on which management
   interface is to be used for managing an MPLS-TP network.  It is
   possible to provision and manage an end-to-end connection across a
   network where some segments are created/managed/deleted, for example
   by NETCONF or SNMP and other segments by CORBA interfaces.  Use of
   any network management interface for one management-related purpose
   does not preclude use of another network management interface for



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   other management-related purposes, or the same purpose at another
   time.  The protocol(s) to be supported are at the discretion of the
   operator.

2.4.  Management- and Control-Specific Terminology

   Data Communication Network (DCN) is the common term for the network
   used to transport Management and Signaling information between:
   management systems and network elements, management systems to other
   management systems, and networks elements to other network elements.
   The Management Communications Network (MCN) is the part of the DCN
   that supports the transport of Management information for the
   Management Plane.  The Signaling Communications Network (SCN) is the
   part of the DCN that supports transport of signaling information for
   the Control Plane.  As shown in , the communication channel
   terminology picture (Figure 5) each technology has its own
   terminology that is used for the channels that support the transfer
   of management and control plane information.  For MPLS-TP, the
   management plane uses the Management Communication Channel (MCC), and
   the control plane uses the Signaling Communication Channel (SCC).

2.5.  Management Channel

   The Communication Channel (CCh) provides a logical channel between
   NEs for transferring Management and/or Signaling information.  Note
   that some technologies provide separate communication channels for
   Management (MCC) and Signaling (SCC).

   MPLS-TP NEs communicate via the DCN.  The DCN connects NEs with
   management systems, NEs with NEs, and management systems with
   management systems.




















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   Common Terminology                   ____
    __________         __________      |    |
   |          |       |          |  /->| NE | \   ____
   |Management|       |Operations| /   |____|  \ |    |
   |Station   | <---> |System    |       |(CCh)  | NE |
   |__________|       |__________| \    _|__   / |____|
                                    \->|    | /
                                       | NE |
                                       |____|
                       Network Elements use a Communication
                       Channel (CCh) for Transport of Information

   Management Terminology               ____
    __________         __________      |    |
   |          |       |          |  /->| NE | \   ____
   |Management|       |Operations| /   |____|  \ |    |
   |Station   | <---> |System    |       |(MCC)  | NE |
   |__________|       |__________| \    _|__   / |____|
                                    \->|    | /
                                       | NE |
                                       |____|
                       Network Elements use a Management
                       Communication Channel (MCC) for Transport
                       of Management Information

   Control Terminology                  ____
    __________         __________      |    |
   |          |       |          |  /->| NE | \   ____
   |Management|       |Operations| /   |____|  \ |    |
   |Station   | <---> |System    |       |(SCC)  | NE |
   |__________|       |__________| \    _|__   / |____|
                                    \->|    | /
                                       | NE |
                                       |____|
                       Network Elements use a Control/Signaling
                       Communication Channel (SCC) for Transport
                       of Signaling Information

                     Communication Channel Terminology

                                 Figure 5










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3.  Fault Management

   A fault is the inability of a function to perform a required action.
   This does not include an inability due to preventive maintenance,
   lack of external resources, or planned actions.  Fault management
   provides the mechanisms to detect, verify, isolate, notify, and
   recover from the fault.

3.1.  Supervision

   ITU-T G.7710 [6] lists five basic categories of supervision that
   provide the functionality necessary to detect, verify, and notify a
   fault.  The categories are: Transmission Supervision, Quality of
   Service Supervision, Processing Supervision, Hardware Supervision,
   and Environment Supervision.  Each of the categories provides a set
   of recommendations to ensure that the fault management process is
   fulfilled.

3.2.  Validation

   ITU-T G.7710 [6] describes a fault cause as a limited interruption of
   the required function.  It is not reasonable for every fault cause to
   be reported to maintenance personnel.  The validation process is used
   to turn fault causes (events) into failures (alarms).

3.3.  Alarm Handling

   Within an element management system, it is important to consider
   mechanisms to support severity assignment, alarm reporting control,
   and logging.

4.  Configuration Management

   Configuration management provides the mechanisms to:

   o  provision the MPLS-TP services

   o  set up security for the MPLS-TP services and MPLS-TP network
      elements

   o  provide the destination for fault notifications and performance
      parameters

   o  configure and control OAM

   Also associated with configuration management are hardware and
   software provisioning and inventory reporting.




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4.1.  LSP Ownership Handover

   MPLS-TP networks can be managed not only by Network Management
   Systems (i.e., Management Plane (MP)), but also by Control Plane (CP)
   protocols.  The utilization of the control plane is not a mandatory
   requirement (see MPLS-TP Requirements [2]), but it is often used by
   network operators in order to make network configuration and Label
   Switched Path (LSP) recovery both faster and simpler.

   In networks where both CP and MP are provided, an LSP could be
   created by either (CP or MP).  The entity creating an LSP owns the
   data plane resources comprising that LSP.  Only the owner of an LSP
   is typically able to modify/delete it.  This results in a need for
   interaction between the MP and CP to allow either to manage all the
   resources of a network.

   Network operators might prefer to have full control of the network
   resources during the set-up phase and then allow the network to be
   automatically maintained by the Control Plane.  This can be achieved
   by creating LSPs via the Management Plane and subsequently
   transferring LSP ownership to the Control Plane.  This is referred to
   as "ownership handover" RFC 5493 [10].  MP to CP ownership handover
   is then considered a requirement where a Control Plane is in use that
   supports it.  The converse (CP to MP ownership handover) is a feature
   that is recommended -- but not required -- for (G)MPLS networks
   because it has only minor applications (for example, moving LSPs from
   one path to another as a maintenance operation).

   The LSP handover procedure has already been standardized for GMPLS
   networks, where the signaling protocol used is RSVP-TE (RFC 3209
   [1]).  The utilization of RSVP-TE enhancements are defined in [5].

   MP and CP interworking also includes the exchange of information that
   is either requested by the MP, or a notification by the CP as a
   consequence of a request from the MP or an automatic action (for
   example, a failure occurs or an operation is performed).  The CP is
   asked to notify the MP in a reliable manner about the status of the
   operations it performs and to provide a mechanism to monitor the
   status of Control Plane objects (e.g., TE Link status, available
   resources), and to log operations related to Control Plane LSP.
   Logging is one of the most critical aspects because the MP always
   needs to have an accurate history and status of each LSP and all Data
   Plane resources involved in it.








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5.  Performance Management

   Performance statistics could overwhelm a Management Network, so it is
   important to provide flexible instrumentation that enables control
   over the amount of performance data to be collected.  Mechanisms for
   limiting the quantity of information collected are well known and
   deployed in IETF standards (see RFC 2819 (RMON) [8] and RFC 4502
   (RMON2) [9]).  The details of the performance data collected
   (including loss and delay measurement data) are found in the "Network
   Management Requirements for MPLS-based Transport Networks" document
   [3].

   A distinction is made between performance data that is collected on-
   demand and data that is collected proactively.  The definitions of
   on-demand and proactive measurement are provided for OAM in the
   "Network Management Requirements for MPLS-based Transport Networks"
   document [3].

   On-demand measurement provides the operator with the ability to do
   performance measurement for maintenance purpose, such as diagnosis or
   to provide detailed verification of proactive measurement.  It is
   used typically on specific LSP service instances for a limited time,
   thus limiting its impact on network performance under normal
   operations.  Therefore, on-demand measurement does not result in
   scaling issues.

   Proactive measurement is used continuously over time after being
   configured with periodicity and storage information.  Data collected
   from proactive measurement are usually used for verifying the
   performance of the service.  Proactive performance monitoring has the
   potential to overwhelm both the process of collecting performance
   data at a network element (for some arbitrary number of service
   instances traversing the NE), and the process of reporting this
   information to the OS.  As a consequence of these considerations,
   operators would typically limit the services to which proactive
   performance measurement would be applied to a very selective subset
   of the services being provided and would limit the reporting of this
   information to statistical summaries (as opposed to raw or detailed
   performance statistics).

6.  Acknowledgements

   The authors/editors gratefully acknowledge the thoughtful review,
   comments and explanations provided by Diego Caviglia, Bernd Zeuner
   and Dan Romascanu.






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7.  Security Considerations

   The ability for the authorized network operator to access EMF
   interfaces (Section 2.3) when needed is critical to proper operation.
   Therefore, the EMF interfaces need to be protected from denial-of-
   service conditions or attack.  The EMF interfaces that use or access
   private information should be protected from eavesdropping, mis-
   configuration, and/or mal-configuration by unauthorized network
   elements, systems, or users.

   Performance of diagnostic functions and path characterization
   involves extracting a significant amount of information about network
   construction that the network operator considers private.

   Section 4.3 of the "Security Framework for MPLS and GMPLS Networks"
   document [14] provides a description of the attacks on the Operation
   and Management Plane and also discusses the background necessary to
   understand security practices in Internet Service Provider
   environments.  The security practices described are applicable to
   MPLS-TP environments.

8.  References

8.1.  Normative References

   [1]   Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and
         G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels",
         RFC 3209, December 2001.

   [2]   Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and
         S. Ueno, "Requirements of an MPLS Transport Profile", RFC 5654,
         September 2009.

   [3]   Lam, K., Mansfield, S., and E. Gray, "Network Management
         Requirements for MPLS-based Transport Networks", RFC 5951,
         September 2010.

   [4]   Bocci, M., Bryant, S., Frost, D., Levrau, L., and L. Berger, "A
         Framework for MPLS in Transport Networks", RFC 5921, July 2010.

   [5]   Caviglia, D., Ceccarelli, D., Bramanti, D., Li, D., and S.
         Bardalai, "RSVP-TE Signaling Extension for LSP Handover from
         the Management Plane to the Control Plane in a GMPLS-Enabled
         Transport Network", RFC 5852, April 2010.

   [6]   International Telecommunication Union, "Common equipment
         management function requirements", ITU-T Recommendation G.7710/
         Y.1701, July 2007.



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   [7]   International Telecommunication Union, "Architecture and
         specification of data communication network",
         ITU-T Recommendation G.7712/Y.1703, June 2008.

8.2.  Informative References

   [8]   Waldbusser, S., "Remote Network Monitoring Management
         Information Base", STD 59, RFC 2819, May 2000.

   [9]   Waldbusser, S., "Remote Network Monitoring Management
         Information Base Version 2", RFC 4502, May 2006.

   [10]  Caviglia, D., Bramanti, D., Li, D., and D. McDysan,
         "Requirements for the Conversion between Permanent Connections
         and Switched Connections in a Generalized Multiprotocol Label
         Switching (GMPLS) Network", RFC 5493, April 2009.

   [11]  International Telecommunication Union, "Principles for a
         telecommunication management network", ITU-T Recommendation
         M.3010, April 2005.

   [12]  International Telecommunication Union, "Principles for the
         Management of Next Generation Networks", ITU-T Recommendation
         M.3060/Y.2401, March 2006.

   [13]  International Telecommunication Union, "Considerations for a
         telecommunication management network", ITU-T Recommendation
         M.3013, February 2000.

   [14]  Fang, L., "Security Framework for MPLS and GMPLS Networks",
         RFC 5920, July 2010.

   [15]  Andersson, L., Helvoort, H., Bonica, R., Romascanu, D., and S.
         Mansfield, ""The OAM Acronym Soup"", Work in progress,
         June 2010.
















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Authors' Addresses

   Scott Mansfield (editor)
   Ericsson
   300 Holger Way
   San Jose, CA  95134
   US

   Phone: +1 724 931 9316
   Email: scott.mansfield@ericsson.com


   Eric Gray (editor)
   Ericsson
   900 Chelmsford Street
   Lowell, MA  01851
   US

   Phone: +1 978 275 7470
   Email: eric.gray@ericsson.com


   Hing-Kam Lam (editor)
   Alcatel-Lucent
   600-700 Mountain Ave
   Murray Hill, NJ  07974
   US

   Phone: +1 908 582 0672
   Email: Kam.Lam@alcatel-lucent.com





















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