RFC 2892 (rfc2892) - Page 2 of 52

The Cisco SRP MAC Layer Protocol

RFC 2892            The Cisco SRP MAC Layer Protocol         August 2000


Table of Contents

    1.  Differences between SRP V1 and V2 .......................  3
    2.  Terms and Taxonomy ......................................  4
        2.1.  Ring Terminology ..................................  4
        2.2.  Spatial Reuse .....................................  5
        2.3.  Fairness ..........................................  6
        2.4.  Transit Buffer ....................................  7
    3.  SRP Overview ............................................  8
        3.1.  Receive Operation Overview ........................  8
        3.2.  Transmit Operation Overview .......................  8
        3.3.  SRP Fairness Algorithm (SRP-fa) Overview ..........  9
        3.4.  Intelligent Protection Switching (IPS) Protocol
              Overview ..........................................  9
    4.  Packet Formats .......................................... 13
        4.1.  Overall Packet Format ............................. 13
        4.2.  Generic Packet Header Format ...................... 14
             4.2.1.  Time To Live (TTL) ......................... 14
             4.2.2.  Ring Identifier (R) ........................ 15
             4.2.3.  Priority Field (PRI) ....................... 15
             4.2.4.  MODE ....................................... 15
             4.2.5.  Parity Bit (P-bit) ......................... 16
             4.2.6.  Destination Address ........................ 16
             4.2.7.  Source Address ............................. 16
             4.2.8.  Protocol Type .............................. 16
        4.3.  SRP Cell Format ................................... 16
        4.4.  SRP Usage Packet Format ........................... 17
        4.5.  SRP Control Packet Format ......................... 18
             4.5.1.  Control Ver ................................ 19
             4.5.2.  Control Type ............................... 19
             4.5.3.  Control TTL ................................ 19
             4.5.4.  Control Checksum ........................... 19
             4.5.5.  Payload .................................... 20
             4.5.6.  Addressing ................................. 20
        4.6.  Topology Discovery ................................ 20
             4.6.1.  Topology Length ............................ 22
             4.6.2.  Topology Originator ........................ 22
             4.6.3.  MAC bindings ............................... 22
             4.6.4.  MAC Type Format ............................ 22
        4.7.  Intelligent Protection Switching (IPS) ............ 23
             4.7.1.  Originator MAC Address ..................... 23
             4.7.2.  IPS Octet .................................. 24
        4.8.  Circulating packet detection (stripping) .......... 24
    5.  Packet acceptance and stripping ......................... 25
        5.1.  Transmission and forwarding with priority ......... 27
        5.2.  Wrapping of Data .................................. 28
    6.  SRP-fa Rules Of Operation ............................... 28
        6.1.  SRP-fa pseudo-code ................................ 30



Tsiang & Suwala              Informational