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diff --git a/doc/rfc/rfc1841.txt b/doc/rfc/rfc1841.txt new file mode 100644 index 0000000..09d445d --- /dev/null +++ b/doc/rfc/rfc1841.txt @@ -0,0 +1,3699 @@ + + + + + + +Network Working Group J. Chapman +Request For Comments: 1841 Cisco Systems, Inc. +Category: Informational D. Coli + Cisco Systems, Inc. + A. Harvey + Cisco Systems, Inc. + B. Jensen + Cisco Systems, Inc. + K. Rowett + Cisco Systems, Inc. + September 1995 + + + PPP Network Control Protocol for LAN Extension + +Status of Memo + + This memo provides information for the Internet community. This memo + does not specify an Internet standard of any kind. Distribution of + this memo is unlimited. + +Abstract + + Telecommunications infrastructure is improving to offer higher + bandwidth connections at lower cost. Access to the network is + changing from modems to more intelligent devices. This informational + RFC discusses a PPP Network Control Protocol for one such intelligent + device. The protocol is the LAN extension interface protocol. + +Table of Contents + + 1.0 Introduction ........................................... 3 + 1.1 LAN Extension Interface Topology ..................... 4 + 1.2 LAN Extension Interface Architecture ................. 5 + 1.3 LAN Extension Interface Protocol ..................... 6 + + 2.0 LAN Extension Interface Protocol Control Packets........ 8 + 2.1 Startup Options ...................................... 8 + 2.2 Remote Command Options ............................... 14 + 2.3 Conditions for Sending PPP-LEX Packet ................ 17 + + 3.0 Filter Protocol Type ................................... 18 + 3.1 LEX_RCMD_REQUEST - Filter Protocol Type............... 19 + 3.2 Response Packets - Filter Protocol Type............... 21 + + 4.0 Filter MAC Address ..................................... 22 + 4.1 LEX_RCMD_REQUEST - Filter MAC Address ................ 23 + 4.2 Response Packets - Filter MAC Address................. 25 + + + +Chapman, et al Informational [Page 1] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + 5.0 Set Priority ........................................... 27 + 5.1 LEX_RCMD_REQUEST - Set Priority ...................... 27 + 5.2 Response Packets - Set Priority ...................... 29 + + 6.0 Disable LAN Extension Ethernet Interface ............... 30 + 6.1 LEX_RCMD_REQUEST - Disable LAN Extension + Ethernet Interface ................................... 31 + 6.2 Response Packets - Disable LAN Extension + Ethernet Interface ................................... 32 + + 7.0 Enable LAN Extension Ethernet Interface ................ 33 + 7.1 LEX_RCMD_REQUEST - Enable LAN Extension + Ethernet Interface ................................... 33 + 7.2 Response Packets - Enable LAN Extension + Ethernet Interface ................................... 34 + + 8.0 Reboot LAN Extension Interface Unit .................... 35 + 8.1 LEX_RCMD_REQUEST - Reboot LAN Extension Interface + Unit ................................................. 35 + 8.2 Response Packets - Reboot LAN Extension + Interface Unit ....................................... 36 + + 9.0 Request Statistics ..................................... 37 + 9.1 LEX_RCMD_REQUEST - Request Statistics ................ 37 + 9.2 LEX_RCMD_ACK - Request Statistics .................... 39 + 9.3 LEX_RCMD_NAK/LEX_RCMD_REJ - Request Statistics ....... 44 + + 10.0 Download Request ...................................... 45 + 10.1 LEX_RCMD_REQUEST - Download Request ................. 46 + 10.2 Response Packets - Download Request.................. 48 + + 11.0 Download Data ......................................... 49 + 11.1 LEX_RCMD_REQUEST - Download Request ................. 49 + 11.2 Response Packets - Download Data .................... 51 + + 12.0 Download Status ....................................... 52 + 12.1 LEX_RCMD_REQUEST - Download Status .................. 53 + 12.2 LEX_RCMD_ACK - Download Status ...................... 54 + 12.3 LEX_RCMD_NAK/LEX_RCMD_REJ - Download Status ......... 56 + + 13.0 Inventory Request ..................................... 56 + 13.1 LEX_RCMD_REQUEST - Inventory Request ................ 57 + 13.2 LEX_RCMD_ACK - Inventory Request .................... 58 + 13.3 LEX_RCMD_NAK/LEX_RCMD_REJ - Inventory Request ....... 61 + + 14.0 LAN Extension Interface Protocol Data Packets ......... 62 + 14.1 Frame Format ........................................ 62 + 14.2 Summary Field Descriptions........................... 63 + + + +Chapman, et al Informational [Page 2] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + NOTES ...................................................... 65 + REFERENCES ................................................. 65 + SECURITY CONSIDERATIONS .................................... 66 + AUTHORS' ADDRESSES ......................................... 66 + +1.0 Introduction + + An increasing number of corporations allow their employees to + telecommute to work due to local government regulations on traffic + and air pollution. Additionally, many businesses are run out of + internetworked home offices and small branch offices. With these + changes in the workplace, more people and businesses require Internet + access from small LANs. + + Today, routers serve the LAN-to-LAN traffic using high-speed WAN + links such as leased lines, ISDN, or Frame Relay. This new breed of + Internet users from home offices and small branch offices may have a + different, less network-literate skill set than those connecting up + to the Internet today. These new users need an alternative to the + complex and hard-to-configure routers currently employed for + connectivity. One such alternative is a LAN extension interface unit. + + A LAN extension interface unit is a hardware device installed at + remote sites (such as a home office or small branch office) that + connects a LAN across a WAN link to a router at a central site. The + following sections introduce a LAN extension interface topology, + architecture, and protocol. + + + + + + + + + + + + + + + + + + + + + + + + +Chapman, et al Informational [Page 3] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + +1.1 LAN Extension Interface Topology + + Figure 1 shows the topology of LAN extension interfaces. The figure + shows two LAN extension interface units connected via a WAN link to a + central or "host router." + + Figure 1 LAN Extension Interface Topology + + ----------------------------------------- + Router + ----------------------------------------- + Virtual Interface Virtual Interface + 123.123.78.1 123.123.89.1 + ......................................... + Serial 0 Serial n + ----------------------------------------- + |<---- WAN Link ---->| + ------------------ ------------------ + | LAN Extension | | LAN Extension | + | Interface Unit | | Interface Unit | + ------------------ ------------------ + | | + ------------------ ------------------ + | | + ------------ ------------ + | End node | | End node | + ------------ ------------ + 123.123.78.2 123.123.46.2 + + Each LAN extension interface unit maps to a virtual interface at the + host router. The virtual interface mirrors the characteristics of the + LAN extension interface unit. To the routing protocols, the virtual + interface looks just like a local interface, but with the bandwidth + of a serial line. The virtual interface keeps the state (up or down) + of the LAN extension interface unit, and identifies each LAN + extension interface unit by its MAC address. + + A LAN extension interface protocol transfers MAC frames from the LAN + extension interface unit across the serial line to the host router. + At the termination point in the router, the router routes the + packets. This topology uses only one subnet per remote LAN rather + than two, as is the case when routers exist on both ends of a WAN + link. Figure 1 shows this subnetting structure. The IP addresses of + the virtual interfaces on the router are in the same subnet as the IP + addresses of the end nodes on the LAN of the LAN extension interface + unit. The LAN extension interface unit itself has no IP address. + + + + + +Chapman, et al Informational [Page 4] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LAN extension interface units resemble bridges, but with the + following distinct differences: + + * LAN extension interface units always depend on a host router. + They cannot operate standalone or even back-to-back with other + LAN extension interface units. + + * LAN extension interface units need not employ any spanning tree + algorithm. + + * (LAN extension interface units transfer MAC frames across a + serial line (like bridges), but a router can either route or + bridge the LAN extension interface data packets. + +1.2 LAN Extension Interface Architecture + + Figure 2 shows the basic LAN extension interface architecture. + + Figure 2 LAN Extension Interface Architecture + + Router LAN Extension Interface + ------------------- ------------------- + | Network Layer | | MAC Layer | + ------------------- ------------------- + | | + ------------------- ------------------- + | |Virtual Interface| | Filters | | + | ------------------- ------------------- | + | | | | + | ------------------- ------------- | + | | PPP | | RCMD | | + | | | | Handler | | + | ------------------- ------------- | + | | | | + | ------------------- ------------------- | + | |Serial Interface | | PPP | | + | ------------------- ------------------- | + | | | | + | | ------------------- | + | | | Serial Interface| | + | | ------------------- | + | | WAN Link | | + | --------------------------------------- | + | | + | Outbound Inbound | + --------------> <--------------- + + + + + +Chapman, et al Informational [Page 5] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + In the inbound direction (from the remote LAN, to the LAN extension + interface unit, across the WAN link, to the host router), the LAN + extension interface unit can filter received frames to optimize WAN + utilization. The LAN extension interface unit can filter frames by + protocol type or by MAC address. Frames that pass through the LAN + extension interface filters go to the WAN protocol state machine. In + Figure 2, this state machine is PPP. The LAN extension interface unit + adds PPP encapsulation and forwards the packet to the router via the + WAN serial link. + + Upon receiving the frame, the host router decapsulates the PPP header + and passes the packet to the virtual interface. From there the + virtual interface handles the packet like any packet received on a + local interface -- by routing or bridging the packet to another + interface, depending on configuration. + + In the outbound direction (from the host router, across the WAN link, + to the LAN extension interface unit, to the LAN), the host router's + virtual interface builds the full MAC header, before adding PPP + encapsulation. The router then sends the packet across the WAN serial + link to the LAN extension interface unit. The LAN extension interface + unit strips the PPP header and forwards the packet directly onto the + LAN. The host router has already determined that the packet needs to + be forwarded to the LAN extension interface unit, hence there is no + need for additional filtering or processing at that end. + + Embedded in the data stream is a control stream for configuring and + managing the LAN extension interface unit from the host router. The + virtual interface makes the remote LAN extension interface unit + appear like a local router interface to the routing protocols. + + Configuration commands and statistics gathering commands are issued + on the router to the virtual interface. The virtual interface formats + the LAN extension interface remote commands into encoded messages and + transfers them in-band with the data packets. The LAN extension + interface unit decodes the remote commands and executes them. + Responses are similarly formatted messages sent by the LAN extension + interface unit to the host router. The remote command messages use a + different encapsulation type than the data packets, as described + later in this document in the "LAN Extension Interface Protocol + Control Packets" and "LAN Extension Interface Protocol Data Packets" + sections. + +1.3 LAN Extension Interface Protocol + + To accommodate this LAN extension interface architecture, a new + Network Control Protocol (NCP) for PPP exists. This NCP is called + PPP-LEX. The basic functionality of PPP-LEX is to encapsulate LAN + + + +Chapman, et al Informational [Page 6] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + extension interface control and data packets. The IETF has assigned + two new protocol types for these functions, as shown in Table 1. + + Table 1 IETF Protocol Types for PPP-LEX + + Protocol Type Function + + 0x8041 Encapsulates control packets + 0x0041 Encapsulates data packets (MAC frames) + + PPP is a natural choice for a LAN extension interface protocol + because it allows for negotiating a specific control protocol and + options at connection time. This means that network administrators do + not have to statically configure the router interface for remote + interfaces. Rather, remote interfaces negotiate the link at + connection time. + + The LAN extension interface protocol employs PPP link operation as + described in RFC 1331, which reads as follows: + + In order to establish communications of a point-to-point link, + each end of the PPP link must first send [Link Control Protocol] + LCP packets to configure and test the data link. After the link + has been established,the peer may be authenticated. Then PPP must + send NCP packets to choose and configure one or more network layer + protocols. Once each of the chosen network-layer protocols has + been configured, datagrams from each network layer protocol can be + sent over the link. + + The link will remain configured for communications until explicit + LCP or NCP packets close the link down, or until some external + event occurs (an inactivity timer expires or network administrator + intervention). (References, [1]) + + Thus, the LAN extension interface unit and the host router exchange + PPP-LCP packets at connection time to dynamically configure and test + the WAN serial link. Once the link reaches an "opened" state, the LAN + extension interface unit and host router exchange PPP-LEX NCP packets + to configure the LAN extension interface protocol. Once it is + configured, the NCP (PPP-LEX) reaches an "opened" state, and PPP + carries the PPP-LEX control and data packets across the serial link. + At this point, link traffic is a any combination of LCPs, PPP-LEX + NCPs, PPP-LEX control packets, and PPP-LEX data packets. + + Note that the LAN extension interface protocol is not a bridging + protocol. The only similarity to the PPP Bridging Control Protocol + (References. [2]) is that the LAN extension interface protocol also + encapsulates MAC frames. + + + +Chapman, et al Informational [Page 7] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + The following sections detail PPP-LEX control packets and data + packets. + +2.0 LAN Extension Interface Protocol Control Packets + + There are two types of PPP-LEX control packets, as follows: + + * Startup options packet + * Remote command options packets + + The startup options packet is the first PPP-LEX NCP packet that the + LAN extension interface unit sends to the host router after the LCP + has reached an "opened" state. This required startup options packet + configures the LAN extension interface protocol and puts the PPP-LEX + NCP in an "opened" state. + + Remote command options are the PPP-LEX NCP packets that control the + functioning and statistics gathering of the LAN extension interface + protocol. + +2.1 Startup Options + + The LAN extension interface unit sends a startup options packet to + the host router to negotiate the following startup options: + + * MAC Type + * MAC Address + * LAN Extension + + The MAC Type startup option informs the host router of the type of + media that the LAN extension interface unit is connected to. For + example, the LAN extension interface unit may be connected to an + Ethernet LAN or a Token Ring LAN. Currently, only Ethernet is + supported. The MAC type tells the host router what type of traffic + the LAN extension interface unit is prepared to receive. If the host + router rejects the MAC type, the LAN extension interface unit sends + the Configure-Request again. + + The MAC Address startup option sends the MAC address of the LAN + extension interface unit to the host router to authenticate the LAN + extension interface unit and bind it to the corresponding virtual + interface at the host router. The host router also inserts the MAC + address in outbound packets. The MAC address is represented in IEEE + 802.3 canonical format. + + The LAN Extension startup option establishes the network layer + protocol (NCP) as PPP-LEX and provides the host router with the LAN + extension interface protocol version number. + + + +Chapman, et al Informational [Page 8] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Each startup option is transmitted in a series of three fields: + Option-Type, Option-Length, and Option-Data fields. The fields are + concatenated in the startup options Configure-Request packet. + + Frame Format + + Figure 3 shows a summary of the frame format for the startup options + packet. The LAN extension interface unit sends this startup options + packet to the host router. The LAN extension interface unit transmits + these fields from left to right. + + Figure 3 Startup Options Frame Format (Configure-Request) + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Address | Control | Protocol Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1 octet) (1) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1 octet) (1) (2) + + LAN Extension Interface Startup Options +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Length | Option-Data | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1 octet) (1) + + Address + + This PPP-specified field is one octet and contains the binary + sequence 11111111 (hexadecimal 0xFF), the All-Stations address. PPP + does not assign individual station addresses. The All-Stations + address must be recognized and received by all devices. For more + information on this field, refer to "The Point-to-Point Protocol + (PPP) for the Transmission of Multi-protocol Datagrams over Point- + to-Point Links." (References, [1]) + + + + + +Chapman, et al Informational [Page 9] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Control + + This PPP-specified field is one octet and contains the binary + sequence 00000011 (hexadecimal 0x03), the Unnumbered Information (UI) + command with the P/F bit set to zero. + + For more information on this field, refer to "The Point-to-Point + Protocol (PPP) for the Transmission of Multi-protocol Datagrams over + Point-to Point Links." (References, [1]) + + Protocol-Type + + The Protocol-Type field is two octets and contains the IETF-assigned + protocol type value. Valid LAN extension interface protocol type + values are as follows: + + * 0x8041 (for control packets) + * 0x0041 (for data packets) + + Because the startup options packet encapsulates LAN extension + interface control data, the valid value for this field is 0x8041. + + Code + + The Code field is one octet and identifies the type of LCP packet + that the LAN extension interface packet is sending. Valid values are + as follows: + + * 0x01 - Configure-Request + * 0x02 - Configure-Ack + * 0x03 - Configure-Nak + * 0x04 - Configure-Rej + + The LAN extension interface unit initiates the startup options + packet; therefore, the valid value for this field is 1. + + Identifier + + The Identifier field is one octet and contains a randomly generated + value. The value aids matching requests and replies. It is + recommended that a non-zero value be used for the identifier. That + is, zero could be used in the future for unsolicited messages from + the LAN extension interface unit. Valid values are 0x01-0xFF. + + + + + + + + +Chapman, et al Informational [Page 10] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Length + + The Length field is two octets and indicates the length of the entire + packet in octets, including the Code, Identifier, Length, and startup + options fields. + + Option-Type + + The Option-Type field is one octet and identifies the startup option + being negotiated. Valid values are as follows: + + * 0x01 - MAC Type + * 0x03 - MAC Address + * 0x05 - LAN Extension + + Option-Length + + The Option-Length field is one octet and specifies the length of the + startup option fields, including the Option-Type, Option-Data, and + Option-Length fields. + + Option-Data + + The Option-Data field contains the data relating to the value + specified in the Option-Type field. That is, if the Option-Type field + specifies MAC type (0x01), then the Option-Data field contains the + MAC type (Ethernet, Token Ring, and so on). If the Option-Type field + specifies MAC address (0x03), then the Option-Data field contains the + actual MAC address. If the Option-Type field specifies LAN Extension + (0x05), then the Option-Data field contains LAN extension interface + software information. The following table defines the contents of the + Option-Data field for each possible Option-Type field value: + + Option-Type Field Value Option-Data + + 0x01 (MAC Type) The most up-to-date value of the MAC type as + specified in the most recent "Assigned + Numbers" RFC. The current valid value from + that RFC follows: + * 0x01: IEEE 802.3/Ethernet with canonical + addresses + 0x03 (MAC Address) The burned-in MAC address in IEEE 802.3 + canonical format. + 0x05 (LAN Extension) The LAN extension interface protocol version + number. 0x01 is the current protocol version + supported. + + + + + +Chapman, et al Informational [Page 11] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Example + + In the Configure-Request packet that it sends to the host router, the + LAN extension interface unit concatenates the Option-Type, Option- + Data, and Option-Length fields for each startup option, as shown in + Figure 4. The LAN extension interface unit transmits these fields + from left to right. + + Figure 4 Sample Startup Options Configure-Request Packet + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF | 0x03 | 0x8041 | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Address Control Protocol-Type + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0x01 | 0x09 | 0x12 | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Type Identifier Length + + LAN Extension Interface Startup Options +<------------------------------------------------ + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0x01 | 0x03 | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Type Option-Length + + ------------------------------> + 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + 0x01 | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Data + + + + + + + + + + + +Chapman, et al Informational [Page 12] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0x03 | 0x08 | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Type Option-Length | + + 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + 0A 0A 0A 0A 0B 0C | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + ---------- Option-Data --------| + + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0x05 | 0x03 | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Type Option-Length + + 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + 0x01 | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Data + + In Figure 4, the Address field always contains 0xFF, and the Control + field always contains 0x03. The Protocol-Type field value is 0x8041 + because the startup options packet is a LAN extension interface + control packet. The Code field value is 0x01 because the LAN + extension interface unit is sending an LCP Configure-Request packet + to configure or negotiate PPP-LEX. The Identifier field contains a + randomly generated number. The Length field gives the total length of + the entire packet. + + The first startup option is the MAC Type startup option. The Option- + Type value for MAC Type is 0x01. The Option-Length field value for + the MAC type startup option is 3 octets. The Option-Data field value + is 0x01 because, in this example, the LAN extension interface unit + connects to an Ethernet LAN using 802.3 canonical addresses. + + The next startup option transmitted is the MAC Address. Its Option- + Type field value is 0x03, its Option-Length field value is 8 octets, + and its Option-Data field value is the actual MAC address. + + Lastly, the LAN Extension startup option is transmitted. Its Option- + Type field value is 0x05, its Option-Length field value is 3 octets, + and its Option-Data field value is the LAN extension interface + protocol version number (0x01). + + + + +Chapman, et al Informational [Page 13] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + The host router responds to this LCP Configure-Request packet with an + LCP Configure-Ack packet, Configure-Nak packet, or Configure-Rej + packet. For more information on these packets, refer to "The Point- + to-Point Protocol (PPP) for the Transmission of Multi-protocol + Datagrams over Point-to-Point Links" RFC. (References, [1]) + +2.2 Remote Command Options + + Once the host router responds to the startup options Configure- + Request packet with a Configure-Ack packet, the PPP-LEX NCP is in an + "opened" state, and the LAN extension interface unit and the host + router freely exchange PPP-LEX data packets and remote command + options packets. + + The host router initiates PPP-LEX remote command options packets to + control the configuration of the LAN extension interface unit and to + gather statistics. There are 11 types of remote command options that + the host router can send in a LEX_RCMD_REQUEST packet to the LAN + extension interface unit. The LAN extension interface unit responds + to a LEX_RCMD_REQUEST packet with a LEX_RCMD_ACK, LEX_RCMD_NAK, or + LEX_RCMD_REJ packet. + + Frame Format + + Figure 5 shows a summary of the frame format for a remote command + options packet. These fields are transmitted from left to right. + + Figure 5 Remote Command Options Frame Format + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Address | Control | Protocol Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1 octet) (1) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1 octet) (1) (2) + + + + + + + +Chapman, et al Informational [Page 14] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LAN Extension Interface Remote Command Options +<-------------------------------- + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1 octet) (1) + + ----------------------------------------------> + 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Length | Option-Data | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2) + + Address + + This PPP-specified field is a single octet and contains the binary + sequence 11111111 (hexadecimal 0xFF), the All-Stations address. PPP + does not assign individual station addresses. The All-Stations + address must be recognized and received by all devices. For more + information on this field, refer to "The Point-to-Point Protocol + (PPP) for the Transmission of Multi-protocol Datagrams over Point- + to-Point Links." (References, [1]) + + Control + + This PPP-specified field is a single octet and contains the binary + sequence 00000011 (hexadecimal 0x03), the Unnumbered Information (UI) + command with the P/F bit set to zero. + + For more information on this field, refer to "The Point-to-Point + Protocol (PPP) for the Transmission of Multi-protocol Datagrams over + Point-to Point Links." (References, [1]) + + Note: Hereafter the Address and Control fields will be represented + together as a 2-octet field containing "0xFF03". + + Protocol-Type + + The Protocol-Type field is two octets and contains the IETF-assigned + protocol type value. Valid LAN extension interface protocol type + values follow: + + * 0x8041 (for control packets) + * 0x0041 (for data packets) + + + + + +Chapman, et al Informational [Page 15] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Because the remote command options packet encapsulates LAN extension + interface control data, the valid value for this field is 0x8041. + + Code + + The Code field is one octet and identifies the type of PPP-LEX + packet. Valid values are as follows: + + * 0x40 - LEX_RCMD_REQUEST packet + * 0x41 - LEX_RCMD_ ACK packet + * 0x42 - LEX_RCMD_NAK packet + * 0x43 - LEX_RCMD_REJ packet + + The host router sends the LEX_RCMD_REQUEST packet, and the LAN + extension interface unit sends the LEX_RCMD_ACK, LEX_RCMD_NAK, and + LEX_RCMD_REJ packets. + + Identifier + + The Identifier field is one octet and contains a randomly generated + value. The value aids matching requests and replies. It is + recommended that a non-zero value be used for the identifier. That + is, zero could be used in the future for unsolicited messages from + the LAN extension interface unit. Valid values are 0x01-0xFF. + + Length + + The Length field is two octets and indicates the length in octets of + the entire packet, including the Code, Identifier, Length, and remote + command options fields. + + Option-Type + + The Option-Type field is one octet and identifies the remote command + option being transmitted. Valid values are as follows: + + * 0x01 - Filter Protocol Type + * 0x02 - Filter MAC Address + * 0x03 - Set Priority + * 0x04 - Disable LAN Extension Ethernet Interface + * 0x05 - Enable LAN Extension Ethernet Interface + * 0x06 - Reboot LAN Extension Interface Unit + * 0x07 - Request Statistics + * 0x08 - Download Request + * 0x09 - Download Data + * 0x0A - Download Status + * 0x0B- Inventory Request + + + + +Chapman, et al Informational [Page 16] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Each remote command option is discussed in detail in its own section + later in this document. + + Option-Flags + + This field is one octet and further specifies the remote command + option, containing specific actions that must be followed. + + Option-Length + + The Option-Length field is two octets and specifies the length in + octets of the remote command option fields, including the Option- + Type, Option-Flags, Option-Length, and Option-Data fields. + + Option-Data + + Option-Data field contains data relating to the remote command option + specified in the Option-Type field. + +2.3 Conditions for Sending PPP-LEX Packet + + This section describes the general conditions under which PPP-LEX + packet types are sent. For specific information by remote command, + refer to the appropriate remote command section later in this + document. + + LEX RCMD_REQUEST Packet + + The host router sends LEX_RCMD_REQUEST packets to the LAN extension + interface unit to initiate a remote command request. Until the host + router receives a LEX_RCMD_ACK, LEX_RCMD_NAK, or LEX_RCMD_REJ packet + from the LAN extension interface unit, the host router continues to + send the LEX_RCMD_REQUEST packet a default number of times, at which + point the host router times out. + + LEX_RCMD_ACK Packet + + The LAN extension interface unit responds to a LEX_RCMD_REQUEST + packet with a LEX_RCMD_ACK packet when it correctly receives the + request and is able to perform the request. + + LEX RCMD_NAK Packet + + The LAN extension interface unit responds to a LEX_RCMD_REQUEST + packet with a LEX_RCMD_NAK packet when the LAN extension interface + unit recognizes all the elements of the remote command option, but + some elements are not acceptable. Upon receipt of a LEX_RCMD_NAK + packet, the host router immediately stops sending the request. + + + +Chapman, et al Informational [Page 17] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LEX RCMD_REJ Packet + + The LAN extension interface unit responds to a LEX_RCMD_REQUEST + packet with a LEX_RCMD_REJ packet when the Option-Type value in the + request packet is invalid. Invalid Option-Type values are those less + than 0x01 or greater than 0x0B. Currently, this is the only condition + under which the LAN extension interface unit sends a LEX_RCMD_REJ + packet. Upon receipt of a LEX_RCMD_REJ packet, the host router + immediately stops sending the request. + + The following sections detail each of the 11 remote command options. + The sections provide a general description of the option and then + specify the option's Option-Type, Option-Flags, Option-Length, and + Option-Data fields. In addition, the sections describe the return + messages from the LAN extension interface unit. + +3.0 Filter Protocol Type + + The host router sends a LEX_RCMD_REQUEST packet with an Option-Type + of 0x01 to the LAN extension interface unit to configure the LAN + extension interface unit to filter inbound packets by protocol type. + A protocol type filter determines whether or not the LAN extension + interface unit forwards packets of a specific protocol type to the + host router. A protocol type filter consists of a 16-bit value, 16- + bit mask, and a permit or deny field. (See the "Option-Data Field + Descriptions" section for more information on these filter fields.) + + A LEX_RCMD_REQUEST packet can contain 0 to 200 (depending on MTU + size) protocol type filters. When a LEX_RCMD_REQUEST packet contains + multiple filters, they are concatenated. + + The LAN extension interface unit applies the protocol type filters to + each inbound packet's protocol type field in the order in which the + filters exist in the filter table. A packet must be permitted by one + of the filters before the LAN extension interface unit can forward + the packet across the serial link. + + The following example is a filtering algorithm: + + if (protocol_type_field & (~filter_mask)) == filter_value) + if (permit/deny_field == PERMIT) <forward packet on serial LAN> + else <DROP PACKET> + + The protocol type filter should also be applied to the DIX type code + field of Ethernet II frames as well as to IEEE 802.2 SNAP packets. + + + + + + +Chapman, et al Informational [Page 18] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + +3.1 LEX RCMD_REQUEST-Filter Protocol Type + + Figure 6 shows a frame format summary of a LEX_RCMD_REQUEST packet + for the Filter Protocol Type remote command option. The host router + transmits the fields from left to right. + + Figure 6 LEX_RCMD_REQUEST Packet Frame Format - Filter Protocol Type + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + LAN Extension Interface Remote Command Options +<-------------------------------- + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) + + ----------------------------------------------> + 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Length | Option-Data | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2) + + Where the Option-Data field contains the following fields: + + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Value (16 bits) | Value (16 bits) | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Permit/Deny (16 bits) | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + + + +Chapman, et al Informational [Page 19] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Summary Field Descriptions + + For a complete description of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Options, refer to the "Remote Command Options" section + earlier in this document. The following table provides a summary of + these fields when sending a LEX_RCMD_REQUEST packet that configures + the LAN extension interface unit to filter by protocol type. + + Table 2 Field Values for LEX_RCMD_REQUEST Packet-Filter Protocol Type + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + Identifier Valid values: 0x01-0xFF + Length Minimum length = 12 octets + Maximum length = 1212 octets + Option-Type 0x01 (Filter Protocol Type) + Option-Flags None + Option-Length Minimum length = 4 octets + Maximum length = 1204 octets + Option-Data Zero or more filters to be applied at + the LAN extension interface unit. See the + following "Option-Data Field Descriptions" + for details. + + Option-Data Field Descriptions + + The following three Option-Data fields are used in conjunction to + specify a protocol type filter: + + * Value + + The Value field contains a 16-bit value that is any Ethernet type + code. Refer to the "Assigned Numbers" RFC for valid Ethernet type + codes. (References, [4]). + + * Mask + + The Mask field contains a 16-bit "wild card" mask. That is, this + field contains a 16-bit number whose ones bits correspond to the type + code bits to be ignored during the comparison. Thus, the mask + excludes bits from the comparison in the protocol type filter. + + + + + + + +Chapman, et al Informational [Page 20] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + * Permit/Deny + + The Permit/Deny field determines whether a protocol type filter + permits or denies inbound frames to pass to the host router. A permit + value is a non-zero value that allows frames of a specific protocol + type to pass to the host router. A deny value is a zero value that + does not allow frames of a specific protocol type to pass to the host + router. + + Implementation Notes + + Each LEX_RCMD_REQUEST packet is a complete specification of all + protocol type filters and replaces any previously established + filters. + + Note the following special cases: + + * A LEX_RCMD_REQUEST packet with an Option-Length field equal + to four (without any filter entries) instructs the LAN extension + interface unit to turn off protocol type filtering. All MAC + protocol types are forwarded. + + * A LEX_RCMD_REQUEST packet with a filter entry of 0x0000 in the + Value field, 0xFFFF in the Mask field, and a positive value in the + Permit/Deny field means that if previous filters in the filter list + do not permit the inbound packet then this filter entry will. This + filter entry is typically the last filter in a list of filters + contained within the Option-Data field. + + * A LEX_RCMD_REQUEST packet with a filter entry of 0x0000 in the + Value field, 0xFFFF in the Mask field, and a zero in the + Permit/Deny field, means that the LAN extension interface unit must + deny all protocol types. This filter is typically the last filter in + a list of filters contained within the Option-Data field. + +3.2 Response Packets - Filter Protocol Type + + The following packets are valid responses to the Filter Protocol Type + LEX_RCMD_REQUEST packet: + + * LEX_RCMD_ACK - Filter Protocol Type + + The LAN extension interface unit sends a LEX_RCMD_ACK packet in + response to the Filter Protocol Type LEX_RCMD_REQUEST packet when the + LAN extension interface unit correctly receives the Filter Protocol + Type remote command option and applies all filter entries to its + filter table. All filter entries are returned to the host router in + the LEX_RCMD_ACK packet. + + + +Chapman, et al Informational [Page 21] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + * LEX_RCMD_NAK - Filter Protocol Type + + The LAN extension interface unit sends a LEX_RCMD_NAK packet in + response to the Filter Protocol Type LEX_RCMD_REQUEST packet when the + request contains an incorrect number of bytes in the filter or when + there are no more filter entries available. The LAN extension + interface unit continues to use the previous filter table (that is, + the filter table that existed prior to the receipt of the request). + The host router should signal an error to the user/network + administrator. All filter entries are returned to the host router in + the LEX_RCMD_NAK packet. + + * LEX_RCMD-REJ - Filter Protocol Type + + See the "Conditions for Sending PPP-LEX Packets" section earlier in + this document for more information on this packet type. + + Table 3 summarizes the field values of Filter Protocol Type + LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets. + + Table 3 Field Values for Response Packets - Filter Protocol Type + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x41 (LEX_RCMD_ACK packet) + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length The same value as that sent by the + LEX_RCMD_REQUEST packet + Option-Type 0x01 (Filter Protocol Type) + Option-Flags None + Option-Length The same value as that sent by the + LEX_RCMD_REQUEST packet + Option-Data The filter entries sent in the + LEX_RCMD_REQUEST packet + +4.0 Filter MAC Address + + The host router sends a LEX_RCMD_REQUEST packet with an Option-Type + of 0x02 to the LAN extension interface unit to configure the LAN + extension interface unit to filter inbound packets by source MAC + address. A MAC address filter determines whether or not the LAN + extension interface unit forwards packets with a specific source MAC + + + +Chapman, et al Informational [Page 22] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + address to the host router. A MAC address filter consists of MAC + address, a MAC address mask, and a permit or deny field. (See the + "Option-Data Field Descriptions" section later in this section for + more information on these filter fields.) + + A LEX_RCMD_REQUEST packet can contain 0 to 100 (depending on MTU + size) MAC address filters. When a LEX_RCMD_REQUEST packet contains + multiple filters, they are concatenated. + + The LAN extension interface unit applies MAC address filters to each + inbound packet's source MAC address in the order in which the filters + exist in the filter entry list. A packet must be permitted by one of + the filters before the LAN extension interface unit can forward the + packet across the serial link. + +4.1 LEX RCMD_REQUEST - Filter MAC Address + + Figure 7 shows a frame format summary of a LEX_RCMD_REQUEST packet + for the Filter MAC Address remote command option. The host router + transmits the fields from left to right. + + Figure 7 LEX_RCMD_REQUEST Packet Frame Format - Filter MAC Address + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + + + + + + + + + + + + +Chapman, et al Informational [Page 23] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LAN Extension Interface Remote Command Options +<-------------------------------- + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) + + ----------------------------------------------> + 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- + Option-Length | Option-Data | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- + (2) + +Where the Option-Data field contains the following fields: + + 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 (48 bits).... ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| MAC Address Mask (48 bits).... ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Permit/Deny (16 bits) | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Summary Field Descriptions + + For a complete description of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Options, refer to the "Remote Command Options" section + earlier in this document. Table 4 provides a summary of these fields + when sending a LEX_RCMD_REQUEST packet that configures the LAN + extension interface unit to filter by source MAC address. + + Table 4 Field Values for LEX_RCMD_REQUEST Packet - Filter MAC Address + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + Identifier Valid values: 0x01-0xFF + Length Minimum length = 12 octets + Maximum length = 1412 octets + Option-Type 0x02 (Filter MAC Address) + Option-Flags None + Option-Length Minimum length = 4 octets + + + +Chapman, et al Informational [Page 24] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Maximum length = 1404 octets + Option-Data Zero or more filters to be applied at the + LAN extension interface unit. See the + following "Option-Data Field Description + section for details. + + Option-Data Field Descriptions + + The following three Option-Data fields are used in conjunction to + specify a MAC address filter: + + * MAC Address + + The MAC Address field contains a 48-bit IEEE 802.3 MAC address in + canonical format. + + * MAC Address Mask + + The MAC Address Mask field contains a "wild card" mask. The mask is a + 48-bit hexadecimal number whose ones bits correspond to the MAC + address bits to be ignored during the comparison. The mask excludes + bits from the comparison in the MAC address filter. + + * Permit/Deny + + The Permit/Deny field determines whether or not a MAC address filter + permits or denies inbound frames of a specific MAC address to pass to + the host router. A permit value is a non-zero value that allows + frames of a specific MAC address to pass to the host router. A deny + value is a zero value that does not allow frames of a specific MAC + address to pass to the host router. + + Implementation Notes + + Each LEX_RCMD_REQUEST packet is a complete specification of all MAC + address filters and replaces any previously established filters. + + A LEX_RCMD_REQUEST packet with an Option-Length field equal to four + (without any filter entries) instructs the LAN extension interface + unit to turn off filtering. All MAC addresses, except local + destination addresses cached in the self-learning filter, are + forwarded. + +4.2 Response Packets - Filter MAC Address + + The following packets are valid responses to the Filter MAC Address + LEX_RCMD_REQUEST packet: + + + + +Chapman, et al Informational [Page 25] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + * LEX_RCMD_ACK - Filter MAC Address + + The LAN extension interface unit sends a LEX_RCMD_ACK packet in + response to a Filter MAC Address LEX_RCMD_REQUEST packet when the LAN + extension interface unit correctly receives the Filter MAC Address + remote command option and applies the entries to its filter table. + All MAC address filter entries are returned in the LEX_RCMD_ACK + packet. + + * LEX_RCMD_NAK - Filter MAC Address + + The LAN extension interface unit sends a LEX_RCMD_NAK packet in + response to the Filter MAC Address LEX_RCMD_REQUEST packet when the + request contains an incorrect number of bytes in the filter or when + there are no more filter entries available. The LAN extension + interface unit continues to use the previous filter table (that is, + the filter table that existed prior to the receipt of the request). + The host router should signal an error to the user/network + administrator. All filter entries are returned in the LEX_RCMD_NAK + packet. + + * LEX_RCMD-REJ - Filter MAC Address + + See the "Conditions for Sending PPP-LEX Packets" section earlier in + this document for more information on this packet type. + + Table 5 summarizes the field values of Filter MAC Address + LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets. + + Table 5 Field Values for Response Packets - Filter MAC Address + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x41 (LEX_RCMD_ACK packet) + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length The same value as that sent by the + LEX_RCMD_REQUEST packet + Option-Type 0x02 (Filter MAC Address) + Option-Flags None + Option-Length The same value as that sent by the + LEX_RCMD_REQUEST packet + Option-Data The filter entries sent in the + + + +Chapman, et al Informational [Page 26] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LEX_RCMD_REQUEST packet + +5.0 Set Priority + + The host router sends a LEX_RCMD_ REQUEST with an Option-Type of 0x03 + to the LAN extension interface unit to establish the sending priority + of different protocol type packets from the LAN extension interface + unit to host router. There are four levels of priority: + + * High + * Medium + * Normal + * Low + + Packets are classified according to protocol type and then are queued + to one of four output queues on the LAN extension interface unit that + correspond to the above priority levels. When the LAN extension + interface unit is ready to transmit a packet, it scans the priority + queues in order, from the highest to lowest, to find the highest + priority packet. + +5.1 LEX RCMD_REQUEST - Set Priority + + To establish priority queues for each protocol type, the host router + sends a Set Priority LEX_RCMD_REQUEST packet. Figure 8 shows a frame + format summary of such a LEX_RCMD_REQUEST packet. The host router + transmits the fields from left to right. + + Figure 8 LEX_RCMD_REQUEST Packet Frame Format - Set Priority + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + + + + + +Chapman, et al Informational [Page 27] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LAN Extension Interface Remote Command Options +<-------------------------------- + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) + + ----------------------------------------------> + 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- + Option-Length | Option-Data | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- + (2) + + Where the Option-Data field contains the following fields: + + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Protocol Type (16 bits) | Protocol Value (16 bits) | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Summary Field Descriptions + + For a complete descriptions of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Options, refer to the "Remote Command Options" section + earlier in this document. The following table provides a summary of + these fields when sending a LEX_RCMD_REQUEST packet that sets + priority queuing. + + Table 6 Field Values for LEX_RCMD_REQUEST Packet - Set Priority + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + Identifier Valid values: 0x01-0xFF + Length Minimum length = 12 octets + Maximum length = 1028 octets + Option-Type 0x03 (Set Priority) + Option-Flags None + Option-Length Minimum length = 4 octets + Maximum length = 1020 octets + Option-Data Protocol Type and Priority Value. See the + following "Option-Data Field Description" + section for details. + + + +Chapman, et al Informational [Page 28] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Option-Data Field Descriptions + + The following Option-Data fields set the priority queuing of + different protocol type packets. + + * Protocol Type + + The Protocol Type field contains a 16-bit number that is any Ethernet + type code. See the most recent "Assigned Numbers" RFC for the correct + Ethernet type code. + + * Priority Value + + The Priority Value field specifies the priority queue for the + protocol type specified in the Protocol Type field. Valid values are + as follows: + + - 0 - High priority queue + - 1 - Medium priority queue + - 2 - Normal priority queue + - 3 - Low priority queue + + Sending a LEX_RCMD_REQUEST packet with an Option-Length of four (no + priority entries) disables priority queuing. When disabled, the LAN + extension interface unit transfers all packets at a normal (2) + priority level. When a new priority is specified, it overwrites the + previous setting. + +5.2 Response Packets - Set Priority + + The following packets are valid responses to the Set Priority + + LEX_RCMD_REQUEST packet. + + * LEX_RCMD_ACK - Set Priority + + See the "Conditions for Sending PPP-LEX Packets" section earlier in + this document for more information on this packet type. + + * LEX_RCMD_NAK - Set Priority + + The LAN extension interface unit sends a LEX_RCMD_NAK packet in + response to the Set Priority LEX_RCMD_REQUEST packet when the request + contains an incorrect number of bytes in the message, when necessary + resources are not available, or when the specified priority is + invalid. + + + + + +Chapman, et al Informational [Page 29] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + * LEX_RCMD-REJ - Set Priority + + See the "Conditions for Sending PPP-LEX Packets" section earlier in + this document for more information on this packet type. Table 7 + summarizes the field values of Set Priority LEX_RCMD_ACK, + LEX_RCMD_NAK, and LEX_RCMD_REJ packets. + + Table 7 Field Values for Response Packets - Set Priority + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x41 (LEX_RCMD_ACK packet) + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier A randomly generated value that aids in + matching requests with replies + Length Minimum length = 12 octets + Maximum length = 1028 octets + Option-Type 0x03 (Set Priority) + Option-Flags None + Option-Length Minimum length = 4 octets + Maximum length = 1020 octets + Option-Data Protocol Type and Priority Value sent + in the LEX_RCMD_REQUEST packet + +6.0 Disable LAN Extension Ethernet Interface + + The host router sends a LEX_RCMD_ REQUEST with an Option-Type of 0x04 + to the LAN extension interface unit to disable the LAN extension + Ethernet interface. This remote command option stops data traffic + from the LAN extension interface unit to the host router for + troubleshooting or for reconfiguring the LAN extension interface + unit. This remote command option only affects data traffic. PPP-LEX + control packets can still be transferred over the serial link. + + + + + + + + + + + + + + +Chapman, et al Informational [Page 30] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + +6.1 LEX RCMD_REQUEST - Disable LAN Extension Ethernet Interface + + Figure 9 shows a frame format summary of a LEX_RCMD_REQUEST packet + for the Disable LAN Extension Ethernet Interface remote command + option. The host router transmits the fields from left to right. + + Figure 9 LEX_RCMD_REQUEST Packet Frame Format - + Disable LAN Extension Ethernet Interface + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + LAN Extension Interface Remote Command Options +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | Option-Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + Summary Field Descriptions + + For complete descriptions of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Option, refer to the "Remote Command Options" section + earlier in this document. The following table provides a summary of + these fields when sending a LEX_RCMD_REQUEST packet that disables the + LAN extension interface unit. + + + + + + + + + + +Chapman, et al Informational [Page 31] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Table 8 Field Values for LEX_RCMD_REQUEST Packet - + Disable LAN Extension Ethernet Interface + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + Identifier Valid values: 0x01-0xFF + Length 12 octets + Option-Type 0x04 (Disable LAN Extension Ethernet + Interface) + Option-Flags None + Option-Length 4 octets + Option-Data None + +6.2 Response Packets - Disable LAN Extension Ethernet Interface + + LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD-REJ packets are valid + responses to the Disable LAN Extension Ethernet Interface + LEX_RCMD_REQUEST packet. Refer to the "Conditions for Sending PPP-LEX + Packets" section earlier in this document for more information on + when the LAN extension interface unit sends each of these response + packets. Note that the LAN extension interface unit sends the + LEX_RCMD_ACK packet after shutting down the interface. + + Table 9 summarizes the field values of Disable LAN Extension Ethernet + Interface LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets. + + Table 9 Field Values for Response Packets - + Disable LAN Extension Ethernet Interface + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x41 (LEX_RCMD_ACK packet) + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length 12 octets + Option-Type 0x04 (Disable LAN Extension Ethernet + Interface) + Option-Flags None + Option-Length 4 octets + Option-Data None + + + +Chapman, et al Informational [Page 32] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + +7.0 Enable LAN Extension Ethernet Interface + + The host router sends a LEX_RCMD_ REQUEST with an Option-Type of 0x05 + to the LAN extension interface unit to enable the LAN extension + Ethernet interface. This remote command option allows LAN traffic to + flow into the LAN extension interface unit after the interface has + been disabled. + +7.1 LEX RCMD_REQUEST - Enable LAN Extension Ethernet Interface + + Figure 10 shows a frame format summary of a LEX_RCMD_REQUEST packet + for an Enable LAN Extension Ethernet Interface remote command option. + The host router transmits the fields from left to right. + + Figure 10 LEX_RCMD_REQUEST Packet Frame Format - Enable LAN Extension + Ethernet Interface + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + LAN Extension Interface Remote Command Options +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | Option-Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + Summary Field Descriptions + + For complete descriptions of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Option, refer to the "Remote Command Options" section + earlier in this document. Table 10 provides a summary of these fields + when sending a LEX_RCMD_REQUEST packet that enables the LAN extension + + + +Chapman, et al Informational [Page 33] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Ethernet interface. + + Table 10 Field Values for LEX_RCMD_REQUEST Packet - + Enable LAN Extension Ethernet Interface + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + Identifier Valid values: 0x01-0xFF + Length 12octets + Option-Type 0x05 (Enable LAN Extension Ethernet + Interface) + Option-Flags None + Option-Length 4 octets + Option-Data None + +7.2 Response Packets - Enable LAN Extension Ethernet Interface + + LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD-REJ packets are valid + responses to the Enable LAN Extension Ethernet Interface + LEX_RCMD_REQUEST packet. Refer to the "Conditions for Sending PPP-LEX + Packets" section earlier in this document for more information on + when the LAN extension interface unit sends each of these response + packets. Note that the LAN extension interface unit sends the + LEX_RCMD_ACK packet after enabling the interface. + + The frame format of the response packets mirrors that of the request. + Table 11 summarizes the field values of Enable LAN Extension Ethernet + Interface LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets. + + Table 11 Field Values for Response Packets - + Enable LAN Extension Ethernet Interface + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x41 (LEX_RCMD_ACK packet) + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length 12 octets + Option-Type 0x05 (Enable LAN Extension Ethernet + Interface) + + + +Chapman, et al Informational [Page 34] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Option-Flags None + Option-Length 4 octets + Option-Data None + +8.0 Reboot LAN Extension Interface Unit + + The host router sends a LEX_RCMD_REQUEST packet with an Option-Type + of 0x06 to the LAN extension interface unit to cause the LAN + extension interface unit to reboot itself. The Option-Flags field + specifies the boot mode for the LAN extension interface unit. There + are two boot modes: + + * The first boot mode (Option-Flag 0x00) is the default. The + default boot mode causes the LAN extension interface unit to + check for a valid Flash image and to boot from it if it exists. + If a valid Flash image does not exist, the default boot mode + causes the LAN extension interface unit to boot from the PROM + image. Similarly, if the Flash image is bad, then the LAN + extension interface unit recovers by booting from the PROM image. + + * The second boot mode (Option-Flag 0x01) forces the LAN extension + interface unit to boot from the PROM image. + +8.1 LEX RCMD_REQUEST - Reboot LAN Extension Interface Unit + + Figure 11 shows a frame format summary of a LEX_RCMD_REQUEST packet + for a Reboot LAN Extension Interface Unit remote command option. The + host router transmits the fields from left to right. + + Figure 11 LEX_RCMD_REQUEST Packet Frame Format - + Reboot LAN Extension Interface Unit + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + + + +Chapman, et al Informational [Page 35] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LAN Extension Interface Remote Command Options +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | Option-Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + Summary Field Descriptions + + For complete descriptions of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Option, refer to the "Remote Command Options" section + earlier in this document. Table 12 provides a summary of these fields + when sending a LEX_RCMD_REQUEST packet that instructs the LAN + extension interface unit to reboot. + + Table 12 Field Values for LEX_RCMD_REQUEST Packet - + Reboot LAN Extension Interface Unit + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + Identifier Valid values: 0x01-0xFF + Length 12 octets + Option-Type 0x06 (Reboot LAN Extension Interface Unit) + Option-Flags Valid values: + * 0x00 - Reboot from Flash image if it + exists. If not, reboot from PROM. (This + value does not force the LAN extension + interface unit to reboot from PROM.) + * 0x01 - Reboot from PROM explicitly. + Option-Length 4 octets + Option-Data None + +8.2 Response Packets - Reboot LAN Extension Interface Unit + + LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD-REJ packets are valid + responses to the Reboot LAN Extension Interface Unit LEX_RCMD_REQUEST + packet. Refer to the "Conditions for Sending PPP-LEX Packets" section + earlier in this document for more information on when the LAN + extension interface unit sends each of these response packets. Note + that the LAN extension interface unit reboots after sending the + LEX_RCMD_ACK packet. + + + + + +Chapman, et al Informational [Page 36] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + The frame format for the response packets mirrors that of the + request. Table 13 summarizes the field values for Reboot LAN + Extension Interface Unit LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ + packets. + + Table 13 Field Values for Response Packets - + Reboot LAN Extension Interface Unit + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x41 (LEX_RCMD_ACK packet) + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier The same value as that sent in the + LEX_RCMD_REQUEST packet + Length 12 octets + Option-Type 0x06 (Reboot LAN Extension Interface Unit) + Option-Flags Valid values: + * 0x00 - Reboot from Flash image if it + exists. If not, reboot from PROM. (This + value does not force the LAN extension + interface unit to reboot from PROM.) + * 0x01 - Reboot from PROM explicitly. + Option-Length 4 octets + Option-Data None + +9.0 Request Statistics + + The host router issues a LEX_RCMD_REQUEST packet with an Option-Type + of 0x07 to obtain statistics information from the LAN extension + interface unit. The host router may want statistics information about + the following: + + * Serial interface only + * LAN interface only + * Both the serial and LAN interfaces + + The host router may also send a Statistics Request LEX_RCMD_REQUEST + packet to reset statistics in the LAN extension interface unit. + +9.1 LEX RCMD_REQUEST - Request Statistics + + Figure 12 shows a summary frame format of a LEX_RCMD_REQUEST packet + for a Statistics Request remote command option. The host router + transmits the fields from left to right. + + + +Chapman, et al Informational [Page 37] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Figure 12 LEX_RCMD_REQUEST Packet Frame Format - Request Statistics + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + LAN Extension Interface Remote Command Option +<--------------------------------------------------------------> + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 0 1 2 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | Option-Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + +Summary Field Descriptions + + For complete descriptions of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Option, refer to the "Remote Command Options" section + earlier in this document. Table 14 provides a summary of these fields + when sending a LEX_RCMD_REQUEST packet that requests statistics of + the LAN extension interface unit. + + Table 14 Field Values for LEX_RCMD_REQUEST Packet - + Request Statistics + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + Identifier Valid values: 0x01-0xFF + Length 12 octets + Option-Type 0x07 (Request Statistics) + Option-Flags Valid values: + * 0x01 - Resets serial statistics in the LAN + + + +Chapman, et al Informational [Page 38] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + extension interface unit + * 0x02 - Returns serial statistics from the + LAN extension interface unit + * 0x04 - Returns LAN statistics from the LAN + extension interface unit + * 0x08 - Resets LAN statistics in the LAN + * extension interface unit + If both serial and LAN statistics are + desired, the corresponding bits of this + field should be set (that is, 0x06). The + serial interface statistics appear in the + response packet before the LAN statistics. + Option-Length 4 octets + Option-Data None + +9.2 LEX RCMD_ACK - Request Statistics + + The normal response to a Statistics Request LEX_RCMD_REQUEST packet + is a LEX_RCMD_ACK packet. This acknowledgment packet has an Option- + Type, an Option-Flags, and an Option-Length field followed by one or + two blocks of statistics data. The value in the Option-Flags field + indicates whether the packet has one or two blocks of statistics. For + more information on these values, see the following "Summary Field + Descriptions" section. + + The frame format for the Statistics Request LEX_RCMD_ACK packet + follows. The LAN extension interface unit transmits the fields from + left to right. + + Figure 13 LEX_RCMD_ACK Packet Frame Format - Request Statistics + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + + + + +Chapman, et al Informational [Page 39] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LAN Extension Interface Remote Command Options +<-------------------------------- + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) + + -----------------------------------------------> + 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Length | Option-Data | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2) + + Where the Option-Data fields contains one or both of the following + statistics blocks: + + Serial Interface Statistics Block: + + (32 bits) ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Number of Packets Received | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Number of CRC Erros | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Number of Framing Errors | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Number of Overruns | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Number of Packets Dropped | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Number of Frame Aborts | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Number of Packets in Error | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Number of Packets Dropped Due to Lack of | +| Buffer Descriptors | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Time of Last Packet Received | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Average Data Rate | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Average Packet Rate | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Number of Octets Received | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Input, Number of Packets Dropped Due to No Buffers| + + + +Chapman, et al Informational [Page 40] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Packets Transmitted | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Packets with Error Transmissions| ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Under-run Errors | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Packets in Low Priority Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Size of Low Priority Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Packets Dropped in Low Priority | +| Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Packets in Normal Priority Queue| ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Size of Normal Priority Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Packets Dropped in Normal | +| Priority Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Packets in Medium Priority Queue| ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Size of Medium Priority Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Packets Dropped in | +| Medium Priority Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Packets in High Priority Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Size of High Priority Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Packets Dropped in High | +| Priority Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Time of Last Packet Transmitted | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Carrier Transitions | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Transmitted Data Rate | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Line Output, Number of Octets Transmitted | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + + + + + +Chapman, et al Informational [Page 41] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Lan Interface Statistics Block: + + (32 bits) ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Packets Received | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Packets Received with CRC Errors | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Packets Received with Framing Errors | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Overruns | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Packets Dropped Due to Congestion | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Frame Aborts | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Broadcast Packets Received | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Packets Received with Errors | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Packets Dropped Due to Lack of Buffer | +| Descriptors | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Runts (Too Small Packets) Received | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Time of Last Packet Received | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Average Data Rate | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Average Packet Rate | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Octets Received | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Input, Number of Packets Dropped Due to Lack of Buffers | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Output, Number of Packets Transmitted | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Output, Number of Packets Transmitted with Errors | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Output, Number of Under-runs | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Output, Number of Collisions (Ethernet) | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Output, Number of Packets in Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + + +Chapman, et al Informational [Page 42] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + +| LAN Output, Queue Size | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Output, Number of Packets Dropped in Queue | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Output, Time of Last Packet Transmitted | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Output, Transmit Data Rate | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Output, Transmit Packet Rate | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN Output, Number of Octets Transmitted | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LAN, Number of Interface Resets | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Note: Counts are cumulative since last counter reset. Time stamps + are in milliseconds since last given event. Packet rates are in + packets per second (averaged). + + Summary Field Descriptions + + For complete descriptions of the fields in the PPP Header, the LAN + Extension Protocol Header, and the LAN Extension Remote Command + Option, refer to the "Remote Command Options" section earlier in this + document. The following table provides a summary of these fields for + a LEX_RCMD_ACK packet that sends statistics to the host router. + + Table 15 Field Values for LEX_RCMD_ACK Packet - Request Statistics + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x41 (LEX_RCMD_ACK packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length Minimum length = 120 octets + Maximum length = 140 octets + Option-Type 0x07 (Request Statistics) + Option-Flags The LAN extension interface unit always sets + this field to reflect the actions taken in + response to the LEX_RCMD_ACK packet. Valid + values: + * 0x01 - Reset serial statistics in the LAN + extension interface unit + * 0x02 - Return serial statistics from the + LAN extension interface unit + * 0x04 - Return LAN statistics from the LAN + + + +Chapman, et al Informational [Page 43] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + extension interface unit + * 0x08 - Reset LAN statistics in the LAN + extension interface unit + If both serial and LAN statistics are + returned, the corresponding bits of this + field should are set (that is, 0x06). The + serial interface statistics appear in the + response packet before the LAN statistics. + Option-Length Minimum length = 116 octets + Maximum length = 136 octets + Option-Data The Serial Interface Statistics Block, the + LAN Interface Statistics Block, or both the + Serial Interface and LAN Interface + Statistics blocks. When the Option-Data + contains both blocks, the Serial Interface + Block precedes the LAN Interface Block. + Statistics values that the LAN extension + interface unit does not collect/support + are retuned with a value of zero. + + Implementation Notes + + If the LAN extension interface unit does not implement the capability + of sending the serial and LAN interface statistics blocks separately, + the implementation may always return both statistics blocks (with the + Option-Flags and Option-Length fields containing the appropriate + corresponding values). + + An implementation, such as a Token Ring LAN implementation, can + collect a different set of statistics than shown above by defining a + new statistics request type remote command option. + +9.3 LEX RCMD_NAK/LEX RCMD_REJ - Request Statistics + + The LAN extension interface unit sends a LEX_RCMD_NAK packet when the + Statistics Request LEX_RCMD_REQUEST packet did not specify the type + of statistics the host router wants. That is, the request's Option- + Flags field equals zero. + + Refer to the "Conditions for Sending PPP-LEX Packets" section earlier + in this document for information on when the LAN extension interface + unit sends a Request Statistics LEX_RCMD_REJ packet. + + The frame format for the LEX_RCMD_NAK and LEX_RCMD_REJ packets is the + same as that of the Statistics Request LEX_RCMD_REQUEST packet. Table + 16 summarizes the appropriate field values for the Statistics Request + LEX_RCMD_NAK and LEX_RCMD_REJ packets. + + + + +Chapman, et al Informational [Page 44] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Table 16 Field Values for LEX_RCMD_NAK/LEX_RCMD_REJ Packets - + Request Statistics + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length 12 octets + Option-Type 0x07 (Request Statistics) + Option-Flags The same value as that sent by the + LEX_RCMD_REQUEST packet + Option-Length 4 octets + Option-Data None + +10.0 Download Request + + The host router sends a LEX_RCMD_REQUEST packet with an Option-Type + of 0x08 to alert the LAN extension interface unit that the host + router will be issuing a software download to Flash memory. When the + LAN extension interface unit acknowledges the command, the host + router starts sending download data. + + + + + + + + + + + + + + + + + + + + + + + + + +Chapman, et al Informational [Page 45] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + +10.1 LEX RCMD_REQUEST - Download Request + + Figure 14 shows a summary frame format of a LEX_RCMD_REQUEST packet + for a Download Request remote command option. The host router + transmits the fields from left to right. + + Figure 14 LEX_RCMD_REQUEST Packet Frame Format - Download Request + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + LAN Extension Interface Remote Command Option +<-------------------------------- + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) + + -----------------------------------------------> + 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Length | Option-Data | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2) + + Where the Option-Data field contains the following fields: + + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Block Number (16 bits) | File Size (32 bits).... ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Filename (Max. 64 octets)....... ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + + + +Chapman, et al Informational [Page 46] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Summary Field Descriptions + + For a complete description of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Option, refer to the "Remote Command Options" section + earlier in this document. Table 17 provides a summary of these fields + when sending a LEX_RCMD_REQUEST packet that informs the LAN extension + interface unit of an upcoming software download to Flash memory. + + Table 17 Field Values for LEX_RCMD_REQUEST Packet - Download Request + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + Identifier Valid values: 0x01-0xFF + Length Variable depending on size of filename in + the Filename field. Valid range: + Minimum length = 19 octets + Maximum length = 82 octets + Option-Type 0x08 (Download Request) + Option-Flags None + Option-Length Variable depending on size of filename in + the Filename field. Valid range: + Minimum length = 11 octets + Maximum length = 74 octets + Option-Data Block Number, File Size, and Filename of + the code/image to be downloaded. See the + following "Option-Data Field Descriptions" + section for details. + + Option-Data Field Descriptions + + The Option-Data field contains the following fields: + + * Block Number + + The Block Number field contains a value that identifies a contiguous + group of code bits to be downloaded to the LAN extension interface + unit. In the LEX_RCMD_REQUEST packet, the Block Number is always + zero. + + * File Size + + The File Size field contains the size (in octets) of the code to be + downloaded to the LAN extension interface unit. + + + + +Chapman, et al Informational [Page 47] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + * Filename + + The Filename field contains the name of the image to be transferred + to the LAN extension interface unit. + +10.2 Response Packets - Download Request + + The following packets are valid responses to a Download Request + LEX_RCMD_REQUEST packet: + + * LEX_RCMD_ACK - Download Request + + Refer to the "Conditions for Sending PPP-LEX Packets" section earlier + in this document for more information on when the LAN extension + interface unit sends this packet. + + * LEX_RCMD_NAK - Download Request + + The LAN extension interface unit sends a Download Request + LEX_RCMD_NAK packet when the LAN Extension interface unit is + currently programming Flash, when the File Size field value in the + request is greater than the unit's available Flash bytes, when the + LAN extension interface unit is out of memory, or when the Block + Number field value in the request is not zero. + + * LEX_RCMD_REJ - Download Request + + Refer to the "Conditions for Sending PPP-LEX Packets" section earlier + in this document for more information on when the LAN extension + interface unit sends this packet. + + Table 18 summarizes the field values of the Download Request + LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets. + + Table 18 Field Values for Response Packets - Download Request + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x41 (LEX_RCMD_ACK packet) + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length The same value as that sent by the + LEX_RCMD_REQUEST packet + + + +Chapman, et al Informational [Page 48] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Option-Type 0x08 (Download Request) + Option-Flags None + Option-Length The same value as that sent by the + LEX_RCMD_REQUEST packet + Option-Data Block Number, File Size, and Filename of + the code/image to be downloaded. + +11.0 Download Data + + Once the host router receives a Download Request LEX_RCMD_ACK packet + from the LAN extension interface unit, the host router downloads the + data to be written to Flash memory by sending a LEX_RCMD_REQUEST + packet with an Option-Type of 0x09. The host router sends multiple + Download Data LEX_RCMD_REQUEST packets, each with 512 octets of + Option-Data containing the binary data to be programmed into Flash + memory. + + A packet containing Option-Data with less than 512 octets signals the + end of the download data (that is, the end of tile). If the size of + the file being downloaded is an even multiple of 512 bytes, then the + last packet transferred should have an Option-Length of 6. That is, + the last packet transferred should have Option-Data containing the + Block Number field value but no data. A Block Number field value + without data alerts the LAN extension interface unit that this is the + last block to be transmitted. + +11.1 LEX RCMD_REQUEST - Download Data + + The frame format for the Download Data LEX_RCMD_REQUEST packet is + similar to a TFTP frame format. Figure 15 shows a summary frame + format. The host router transmits the fields from left to right. + + Figure 15 LEX_RCMD_REQUEST Packet Frame Format - Download Data + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + + + + + + + + + +Chapman, et al Informational [Page 49] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + LAN Extension Interface Remote Command Option +<-------------------------------- + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) + + -----------------------------------------------> + 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Length | Option-Data | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2) + + Where the Option-Data field contains the following fields: + + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Block Number (16 bits) | | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +| Binary Download Data (Max. 512 octets)..... | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Summary Field Descriptions + + For a complete descriptions of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Option, refer to the "Remote Command Options" section + earlier in this document. The following table provides a summary of + these fields when sending a LEX_RCMD_REQUEST packet that download + software to the LAN extension interface unit. + + Table 19 Field Values for LEX_RCMD_REQUEST Packet - Download Data + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + + + +Chapman, et al Informational [Page 50] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Identifier Valid values: 0x01-0xFF + Length Minimum length = 14 octets + Maximum length = 526 octets + Option-Type 0x09 (Download Data) + Option-Flags None + Option-Length Minimum length = 6 octets (signals end of + data transfer for a file with a file size + of an even multiple of 512 bytes) + Maximum length = 518 octets + Option-Data Block Number and Download Data. See the + following "Option-Data Field Descriptions" + section for details. + + Option-Data Field Descriptions + + The following Option-Data fields provide the LAN extension interface + unit with download data: + + * Block Number + + The Block Number identifies the contiguous group of code bits to be + downloaded. The host router automatically generates this number. The + first Download Data packet gets a block number of one. The host + router increments this Block Number value by one with every Download + Data LEX_RCMD_REQUEST packet sent to the LAN extension interface + unit. The maximum value of the Block Number is dependent on the + unit's Flash memory size. + + * Download Data + + The Download Data are the actual code bits being downloaded to the + LAN extension interface unit. A maximum of 512 octets of download + data can sent in one Download Data LEX_RCMD_REQUEST packet. + +11.2 Response Packets - Download Data + + The following packets are valid responses to a Download Data + LEX_RCMD_REQUEST packet: + + * LEX_RCMD_ACK - Download Data + + Refer to the "Conditions for Sending PPP-LEX Packets" section earlier + in the document for more information on this packet. + + + + + + + + +Chapman, et al Informational [Page 51] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + * LEX_RCMD_NAK - Download Data + + The LAN extension interface unit sends a Download Data LEX_RCMD_NAK + packet when the LAN extension interface unit is not in the proper + state or when accepting the data will over-run the download buffer. + + * LEX_RCMD_REJ - Download Data + + Refer to the "Conditions for Sending PPP-LEX Packets" section earlier + in the document for more information on this packet. + + Table 20 summarizes the field values of the Download Data + LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets. + + Table 20 Field Values for Response Packets - Download Data + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x41 (LEX_RCMD_ACK packet) + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length 14 octets + Option-Type 0x09 (Download Data) + Option-Flags None + Option-Length 6 octets + Option-Data Block Number only + +12.0 Download Status + + Upon completion of a Download Data sequence, the host router issues a + LEX_RCMD_REQUEST packet with an Option-Type of 0x0A to request status + of the success or failure of the download. A bad checksum of the + image or a malfunctioning Flash memory could cause the download to + fail. + + + + + + + + + + + + +Chapman, et al Informational [Page 52] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + +12.1 LEX RCMD_REQUEST - Download Status + + Figure 16 shows the frame format summary of a LEX_RCMD_REQUEST packet + for a Download Status remote command option. The host router + transmits the fields from left to right. + + Figure 16 LEX_RCMD_REQUEST Packet Frame Format - Download Status + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + LAN Extension Interface Remote Command Option +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | Option-Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + Summary Field Descriptions + + For a complete descriptions of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Option, refer to the "Remote Command Options" section + earlier in this document. Table 21 provides a summary of these fields + when sending a LEX_RCMD_REQUEST packet that requests the download + status of the LAN extension interface unit. + + Table 21 Field Values for LEX_RCMD_REQUEST Packet - Download Status + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + + + +Chapman, et al Informational [Page 53] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Identifier Valid values: 0x01-0xFF + Length 12 octets + Option-Type 0x0A (Download Status) + Option-Flags None + Option-Length 4 octets + Option-Data None + +12.2 LEX RCMD_REQUEST - Download Status + + When the LAN extension interface unit correctly receives the Download + Status LEX_RCMD_REQUEST packet, it returns a LEX_RCMD_ACK packet + containing the appropriate status information in the Option-Data + field. + + Figure 17 shows the frame format for the Download Status LEX_RCMD_ACK + packet. The LAN extension interface unit transmits the fields from + left to right. + + Figure 17 LEX_RCMD_ACK Packet Frame Format - Download Status + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + + + + + + + + + + + + + + + +Chapman, et al Informational [Page 54] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LAN Extension Interface Remote Command Option +<-------------------------------- + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) + + -----------------------------------------------> + 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Length | Option-Data | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2) + + Where the Option-Data field contains the following fields: + + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Status (16 bits) | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Summary Field Descriptions + + For a complete descriptions of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Option, refer to the "Remote Command Options" section + earlier in this document. Table 22 provides a summary of these fields + when sending a status information to the host router. + + Table 22 Field Values for LEX_RCMD_ACK Packet - Download Status + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x41 (LEX_RCMD_ACK packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length 14 octets + Option-Type 0x0A (Download Status) + Option-Flags None + Option-Length 6 octets + Option-Data Status information. See the following + "Option-Data Field Descriptions" section + for details. + + + + + +Chapman, et al Informational [Page 55] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Option-Data Field Descriptions + + The Option-Data field uses the Status field to send the download + status to the host router. The Status field reports the following + status information: + + * 1 - Acknowledgment that no errors occurred + * 3 - Sequence error occurred + * 6 - Flash write error occurred + * 7 - Checksum error + +12.3 LEX RCMD_NAK/LEX RCMD_REJ - Download Status + + Refer to the "Conditions for Sending PPP-LEX Packets" section earlier + in this document for information on when the LAN extension interface + unit sends a Download Status LEX_RCMD_NAK packet and Download Status + LEX_RCMD_REJ packet. + + The frame format for these two response packets mirror the frame + format of the Download Status LEX_RCMD_REQUEST packet. Table 23 + summarizes the field values of the Download Status LEX_RCMD_NAK and + LEX_RCMD_REJ packets. + + Table 23 Field Values for LEX_RCMD_NAK/LEX_RCMD_REJ Packets - Download + Status + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length 12 octets + Option-Type 0x0A (Download Status) + Option-Flags None + Option-Length 4 octets + Option-Data None + +13.0 Inventory Request + + The host router sends a LEX_RCMD_REQUEST packet with an Option-Type + of 0x0B to the LAN extension interface unit to request inventory + information. The host router may use this remote command option to + accomplish the following: + + + + +Chapman, et al Informational [Page 56] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + * Distinguish between different versions of the LAN extension + interface unit for determining their capabilities + + * Determine whether a new version of Flash code should be downloaded + +13.1 LEX RCMD_REQUEST - Inventory Request + + Figure 18 shows the frame format for a LEX_RCMD_REQUEST packet with + an Inventory Request remote command option. The host router transmits + the fields from left to right. + + Figure 18 LEX_RCMD_REQUEST Packet Frame Format - Inventory Request + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + LAN Extension Interface Remote Command Option +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | Option-Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + Summary Field Descriptions + + For a complete description of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Option, refer to the "Remote Command Options" section + earlier in this document. Table 24 provides a summary of these fields + when sending a LEX_RCMD_REQUEST packet that requests inventory + information. + + + + + + +Chapman, et al Informational [Page 57] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Table 24 Field Values for LEX_RCMD_REQUEST Packet-Inventory Request + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x40 (LEX_RCMD_REQUEST packet) + Identifier Valid values: 0x01-0xFF + Length 12 octets + Option-Type 0x0B (Inventory Request) + Option-Flags None + Option-Length 4 octets + Option-Data None + +13.2 LEX RCMD_ACK - Inventory Request + + When it correctly receives the Inventory Request remote command + option and retrieves the inventory information, the LAN extension + interface unit responds with an acknowledgment. This acknowledgment + contains the requested inventory information in the Option-Data + field. + + Figure 19 shows the frame format for the Inventory Request + LEX_RCMD_ACK packet. + + Figure 19 LEX_RCMD_ACK Packet Frame Format - Inventory Request + + PPP Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF03 | Protocol-Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2 octets) (2) + + LAN Extension Interface Protocol Header +<--------------------------------------------------------------> + 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 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Code | Identifier | Length | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) (2) + + + + + + + + + +Chapman, et al Informational [Page 58] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LAN Extension Interface Remote Command Option +<-------------------------------- + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Option-Type | Option-Flags | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (1) (1) + + -----------------------------------------------> + 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Option-Length | Option-Data | + -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + (2) + + Where the Option-Data field contains the following fields: + + (32 bits) ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Flash Size | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Serial Number | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| HW Version | PROM Major Ver| PROM Minor Ver|Flash Major Ver| ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +|Flash Minor Ver| FLAGS | RAM Major Ver | RAM Minor Ver | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| | ++ Mac Address (6 octets) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Summary Field Descriptions + + For a complete description of the fields in the PPP Header, the LAN + Extension Interface Protocol Header, and the LAN Extension Interface + Remote Command Option, refer to the "Remote Command Options" section + earlier in this document. Table 25 provides a summary of these fields + when acknowledging a LEX_RCMD_REQUEST packet that requests inventory + information. + + Table 25 Field Values for LEX_RCMD_ACK Packet - Inventory Request + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code 0x41 (LEX_RCMD_ACK packet) + + + +Chapman, et al Informational [Page 59] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Identifier The same value as that sent by + LEX_RCMD_REQUEST packet + Length 34 octets + Option-Type 0x0B (Inventory Request) + Option-Flags None + Option-Length 26 octets + Option-Data Inventory data. See the following + "Option-Data Field Descriptions" section + for details. + + Option-Data Field Descriptions + + The Option-Data field of the LEX_RCMD_ACK packet uses the following + fields to send inventory data to the host router about the LAN + extension interface unit. + + * Flash Size + + This field contains the LAN extension interface unit's Flash size in + bytes. + + * Serial Number + + This field provides the LAN extension interface unit's serial number. + This is an unassigned, 32-bit number. + + * HW Version + + This field contains the version number of the LAN extension interface + hardware unit. + + * PROM Major Ver + + This field contains part of the version number of the PROM image. + "Major" indicates which major software release this revision belongs + to. For example, if the PROM version number is 1.2, then the major + version number is 1. + + * PROM Minor Ver + + This field contains part of the version number of the PROM image. + "Minor" indicates which minor software release this revision belongs + to. For example, if the PROM version number is 1.2, then the minor + version number is 2. + + + + + + + +Chapman, et al Informational [Page 60] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + * Flash Major Ver + + This field contains the "major" version number of the Flash image. + For example, if the Flash image version number is 1.2, then the major + version number is 1. + + * Flash Minor Ver + + This field contains the "minor" version number of the Flash image. + For example, if the Flash image version number is 1.2, then the minor + version number is 2. + + * FLAGS + + FLAGS report the boot status of the LAN extension interface unit. The + flags are as follows: + + - 0x01 - Running PROM image + - 0x02 - Running Flash image + - 0x04 - PROM image passed checksum + - 0x08 - Flash image passed checksum + + * RAM Major Ver + + This field contains the "major" version number of the running image + in RAM. For example, if the RAM image version number is 1.2, then the + major version number is 1. + + * RAM Minor Ver + + This field contains the "minor" version number of the running image + in RAM. For example, if the RAM image version number is 1.2, then the + minor version number is 2. + + * MAC Address + + The MAC Address is the LAN extension interface unit's burned-in MAC + address in canonical format. This field is six octets. + +13.3 LEX RCMD_NAK/LEX RCMD_REJ - Inventory Request + + Refer to the "Conditions for Sending PPP-LEX Packets" section earlier + in this document for information on when the LAN extension interface + unit sends an Inventory Request LEX_RCMD_NAK packet and Inventory + Request LEX_RCMD_REJ packet. + + The frame format of these two response packets mirrors that of the + request. Table 26 summarizes the field values for such Inventory + + + +Chapman, et al Informational [Page 61] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Request LEX_RCMD_NAK/LEX_RCMD_REJ packets. + + Table 26 Field Values for LEX_RCMD_NAK/LEX_RCMD_REJ Packets - + Inventory Request + + Field Value + Address/Control 0xFF03 (Broadcast address/Unnumbered + information) + Protocol-Type 0x8041 (Control packet) + Code Valid values: + * 0x42 (LEX_RCMD_NAK packet) + * 0x43 (LEX_RCMD_REJ packet) + Identifier The same value as that sent by the + LEX_RCMD_REQUEST packet + Length 12 octets + Option-Type 0x0B (Inventory Request) + Option-Flags None + Option-Length 4 octets + Option-Data None + +14.0 LAN Extension Interface Protocol Data Packets + + When the PPP-LEX NCP is in an "opened" state, the LAN extension + interface unit and the host router also exchange PPP-LEX data packets + (as well as control packets). There is only one type of PPP-LEX data + packet. This data packet is a subset of the PPP-BCP packet format. + + The format subsetting is such that a PPP-BCP implementation will + successfully process a LAN extension interface protocol packet. The + differences are as follows: + + * LAN ID field will not be present. + * LAN FCS field will never be present (that is, the F flag will + always be off [=0]). + * LAN ID flag (I) will always be off. + * Pad field for the serial link will never be present, and the + count field will be 0. + + For detailed information on PPP-BCP packets, refer to the "PPP + Bridging Control Protocol (BCP)" RFC. (References, [2]) + +14.1 Frame Format + + Figure 20 shows the frame format for a PPP-LEX data packet. The MAC + frame is transferred except for the FCS field. The LAN extension + interface unit computes the FCS for packets transferred to the LAN + and strips the FCS for packets destined for the host router. + + + + +Chapman, et al Informational [Page 62] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + Figure 20 PPP-LEX Data Packet Frame Format + + (8 bits) (8 bits) (8 bits) (8 bits) ++-+-+-+-+-+-+-+-+ +| HDLC FLAG | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| 0xFF | 0x03 | 0x0041 | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| F|I|Z|0| Pad | Mac Type | Destination MAC Address | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Destination MAC Address | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Source MAC Address | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| Source MAC Address | Length/Type | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| LLC Data | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| ... | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +| (Serial) HDLC CRC | HDLC FLAG | ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +14.2 Summary Field Descriptions + + HDLC FLAG + + HDLC Frame delimiter. + + 0xFF + + This Address field contains the broadcast address. + + 0x03 + + This Control field contains unnumbered information. + + 0x0041 + + This field contains the IETF-assigned protocol type value for a + PPP-LEX data packet. In this case this field will always contain + 0x0041. + + Flags + + The flags F, I, Z, 0 have the following meanings: + + + + + +Chapman, et al Informational [Page 63] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + * F: Set bit F if the LAN FCS field is present. Because PPP-LEX + data packets do not contain the LAN FCS field, this bit should + not be set (field=0). + + * I: Set bit I if the LAN ID field is present. Because PPP-LEX + data packets do not contain the field, this bit should not be + set (field=0). + + * Z: Set bit Z if IEEE 802.3 Pad must be zero filled to minimum + size. + + * 0: Reserved, must be zero. + + Pad + + Any PPP frame may have padding inserted in the Optional Data Link + Layer Padding field. The value tells the receiving system how many + pad octets to strip off. The LAN extension interface protocol does + not support the Optional Data Link Layer Padding field, so the + value of this field should be zero. + + MAC Type + + This field contains the most up-to-date value of the MAC type as + specified in the most recent "Assigned Numbers" RFC. The current + value is as follows: + + * 1: IEEE 802.3/Ethernet with canonical addresses + + Destination MAC Address + + This field is 6 octets and contains the MAC address of the + destination system as defined by IEEE. The MAC Type field defines + the bit ordering. + + Source MAC Address + + This field is 6 octets and contains the MAC address of the + destination system as defined by IEEE. The MAC Type field defines + the bit ordering. + + Length/Type + + This field is any Ethernet protocol type (See RFC 1700 in the + references "Assigned Numbers"). For IEEE 802.3 frames, this is a + length field. + + + + + +Chapman, et al Informational [Page 64] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + + LLC Data + + This field is the remainder of the MAC frame which is (or would be + if it were present) protected by the LAN FCS. + + (Serial) HDLC CRC + + This is a 16 bit Cyclic Redundancy Check field. + + For complete information on the above fields and their relationship + to PPP-BCP packets, refer to the "PPP Bridging Control Protocol + (BCP)" RFC. (References, [2]) + +Notes + + 1. The LAN extension interface protocol does allow the segmentation + of individual LAN packets across the serial link. Each LAN + packet must be transmitted across the serial link as one PPP-LEX + encapsulation. + + 2. MAC addresses in PPP-LEX packets should be in canonical format. + +References + + [1] Simpson, W., "The Point-To-Point Protocol (PPP) for the + Transmission of Multi-protocol Datagrams over Point-To-Point + Links", RFC 1331, Daydreamer, May 1992. + + [2] Baker, F., and R. Bowen, "PPP Bridging Control Protocol (BCP)", + RFC 1638, ACC, IBM, June 1994. + + [3] Lloyd, B., and W. Simpson, "PPP Authentication Protocols", RFC + 1334, Lloyd & Associates, Daydreamer, October 1992. + + [4] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC 1700, + USC/Information Sciences Institute, October 1994. + + [5] Reynolds, J., and J. Postel, "Standard for the transmission of IP + datagrams over IEEE 802 networks", RFC 1042, USC/Information + Sciences Institute, February 1988. + + + + + + + + + + + +Chapman, et al Informational [Page 65] + +RFC 1841 LAN Extension Interface Protocol September 1995 + + +Security Considerations + + Security issues are not discussed in this memo. + +Authors' Addresses + + Joelle Bafile Chapman, Technical Writer + Cisco Systems, Inc. + 170 West Tasman Drive + San Jose, CA 95134-1706 + + EMail: joelle@cisco.com + + + Dave Coli, Software Engineer + Cisco Systems, Inc. + 170 West Tasman Drive + San Jose, CA 95134-1706 + + EMail: dcoli@cisco.com + + + Andy Harvey, Software Engineer + Cisco Systems, Inc. + 170 West Tasman Drive + San Jose, CA 95134-1706 + + EMail: agh@cisco.com + + + Bent Jensen, Engineering Manager + Cisco Systems, Inc. + 170 West Tasman Drive + San Jose, CA 95134-1706 + + EMail: bent@cisco.com + + + Kevin Rowett, Software Engineer + Cisco Systems, Inc. + 170 West Tasman Drive + San Jose, CA 95134-1706 + + EMail: krowett@cisco.com + + + + + + + +Chapman, et al Informational [Page 66] + |