Cabletron's VLS Protocol Specification
RFC 2642
Document | Type |
RFC - Informational
(August 1999; No errata)
Was draft-rfced-info-cabletron-vls (individual)
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Last updated | 2013-03-02 | ||
Stream | Legacy | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 2642 (Informational) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group L. Kane Request for Comments: 2642 Cabletron Systems Incorporated Category: Informational August 1999 Cabletron's VLS Protocol Specification Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (1999). All Rights Reserved. Abstract The Virtual LAN Link State Protocol (VLSP) is part of the InterSwitch Message Protocol (ISMP) which provides interswitch communication between switches running Cabletron's SecureFast VLAN (SFVLAN) product. VLSP is used to determine and maintain a fully connected mesh topology graph of the switch fabric. Each switch maintains an identical database describing the topology. Call-originating switches use the topology database to determine the path over which to route a call connection. VLSP provides support for equal-cost multipath routing, and recalculates routes quickly in the face of topological changes, utilizing a minimum of routing protocol traffic. Table of Contents 1. Introduction............................................ 3 1.1 Acknowledgments..................................... 3 1.2 Data Conventions.................................... 3 1.3 ISMP Overview....................................... 4 2. VLS Protocol Overview................................... 5 2.1 Definitions of Commonly Used Terms.................. 6 2.2 Differences Between VLSP and OSPF................... 7 2.2.1 Operation at the Physical Layer............... 8 2.2.2 All Links Treated as Point-to-Point........... 8 2.2.3 Routing Path Information...................... 9 2.2.4 Configurable Parameters....................... 9 2.2.5 Features Not supported........................ 9 2.3 Functional Summary.................................. 10 2.4 Protocol Packets.................................... 11 Kane Informational [Page 1] RFC 2642 Cabletron's VLS Protocol Specification August 1999 2.5 Protocol Data Structures............................ 12 2.6 Basic Implementation Requirements................... 12 2.7 Organization of the Remainder of This Document...... 13 3. Interface Data Structure................................ 14 3.1 Interface States.................................... 16 3.2 Events Causing Interface State Changes.............. 18 3.3 Interface State Machine............................. 21 4. Neighbor Data Structure................................. 23 4.1 Neighbor States..................................... 25 4.2 Events Causing Neighbor State Changes............... 27 4.3 Neighbor State Machine.............................. 29 5. Area Data Structure..................................... 33 5.1 Adding and Deleting Link State Advertisements....... 34 5.2 Accessing Link State Advertisements................. 35 5.3 Best Path Lookup.................................... 35 6. Discovery Process....................................... 35 6.1 Neighbor Discovery.................................. 36 6.2 Bidirectional Communication......................... 37 6.3 Designated Switch................................... 38 6.3.1 Selecting the Designated Switch............... 39 6.4 Adjacencies......................................... 41 7. Synchronizing the Databases............................. 42 7.1 Link State Advertisements........................... 43 7.1.1 Determining Which Link State Advertisement Is Newer............. 44 7.2 Database Exchange Process........................... 44 7.2.1 Database Description Packets.................. 44 7.2.2 Negotiating the Master/Slave Relationship..... 45 7.2.3 Exchanging Database Description Packets....... 46 7.3 Updating the Database............................... 48 7.4 An Example.......................................... 49 8. Maintaining the Databases............................... 51 8.1 Originating Link State Advertisements............... 52 8.1.1 Switch Link Advertisements.................... 52 8.1.2 Network Link Advertisements................... 55 8.2 Distributing Link State Advertisements.............. 56 8.2.1 Overview...................................... 57 8.2.2 Processing an Incoming Link State Update Packet............. 58 8.2.3 Forwarding Link State Advertisements.......... 60 8.2.4 Installing LinkShow full document text