RFC 2091 (rfc2091) - Page 2 of 22

Triggered Extensions to RIP to Support Demand Circuits

RFC 2091                      Trigger RIP                   January 1997


   o  MAY or optional -- the item is truly optional and may be followed
      or ignored according to the needs of the implementor.

      The words "should" and "may" are also used, in lower case, in
      their more ordinary senses.

Table of Contents

   1. Introduction ...........................................  2
   2. Overview ...............................................  3
   3. The Routing Database ...................................  5
       3.1. Presumption of Reachability ......................  6
       3.2. Alternative Routes ...............................  6
       3.3. Split Horizon with Poisoned Reverse ..............  7
       3.4. Managing Updates .................................  7
       3.5. Retransmissions ..................................  7
   4. New Packet Types .......................................  8
       4.1. Update Request (9) ...............................  9
       4.2. Update Response (10) .............................  9
       4.3. Update Acknowledge (11) .......................... 10
   5. Packet Formats ......................................... 10
       5.1. Update Header .................................... 10
       5.2. IP Routing Information Protocol Version 1 ........ 11
       5.3. IP Routing Information Protocol Version 2 ........ 11
       5.4. Netware Routing Information Protocol ............. 12
       5.5. Netware Service Advertising Protocol ............. 12
   6. Timers ................................................. 17
       6.1. Database Timer ................................... 17
       6.2. Hold Down Timer .................................. 17
       6.3. Retransmission Timer ............................. 18
       6.4. Over-subscription Timer .......................... 18
   7. Security Considerations ................................ 19
   Appendix A - Implementation Suggestion .................... 20
   References ................................................ 21
   Authors' Addresses ........................................ 22

1. Introduction

   Routers are used on connection oriented networks, such as X.25 packet
   switched networks and ISDN networks, to allow potential connectivity
   to a large number of remote destinations.  Circuits on the Wide Area
   Network (WAN) are established on demand and are relinquished when the
   traffic subsides.  Depending on the application, the connection
   between any two sites for user data might actually be short and
   relatively infrequent.






Meyer & Sherry              Standards Track