RFC 1638 (rfc1638) - Page 2 of 28

PPP Bridging Control Protocol (BCP)

RFC 1638                      PPP Bridging                     June 1994


           4.1.4  Separation of Spanning Tree Domains .............   11
        4.2       Bridged LAN Traffic .............................   12
        4.3       Spanning Tree Bridge PDU ........................   16
     5.     BCP Configuration Options .............................   17
        5.1       Bridge-Identification ...........................   17
        5.2       Line-Identification .............................   19
        5.3       MAC-Support .....................................   20
        5.4       Tinygram-Compression ............................   21
        5.5       LAN-Identification ..............................   22
        5.6       MAC-Address .....................................   23
        5.7       Spanning-Tree-Protocol ..........................   24
        APPENDICES ................................................   26
        A.     Tinygram-Compression Pseudo-Code ...................   26
        SECURITY CONSIDERATIONS ...................................   27
        REFERENCES ................................................   27
     ACKNOWLEDGEMENTS .............................................   28
     CHAIR'S ADDRESS ..............................................   28
     AUTHOR'S ADDRESS .............................................   28

1.  Historical Perspective

   Two basic algorithms are ambient in the industry for Bridging of
   Local Area Networks.  The more common algorithm is called
   "Transparent Bridging", and has been standardized for Extended LAN
   configurations by IEEE 802.1.  The other is called "Source Route
   Bridging", and is prevalent on IEEE 802.5 Token Ring LANs.

   The IEEE has combined these two methods into a device called a Source
   Routing Transparent (SRT) bridge, which concurrently provides both
   Source Route and Transparent bridging.  Transparent and SRT bridges
   are specified in IEEE standard 802.1D [3].

   Although IEEE committee 802.1G is addressing remote bridging [2],
   neither standard directly defines the mechanisms for implementing
   remote bridging.  Technically, that would be beyond the IEEE 802
   committee's charter.  However, both 802.1D and 802.1G allow for it.
   The implementor may model the line either as a component within a
   single MAC Relay Entity, or as the LAN media between two remote
   bridges.












Baker & Bowen