RFC 2338 (rfc2338) - Page 2 of 27

Virtual Router Redundancy Protocol

RFC 2338                          VRRP                        April 1998


Table of Contents

   1.  Introduction...............................................2
   2.  Required Features..........................................5
   3.  VRRP Overview..............................................6
   4.  Sample Configurations......................................8
   5.  Protocol...................................................9
      5.1  VRRP Packet Format....................................10
      5.2  IP Field Descriptions.................................10
      5.3  VRRP Field Descriptions...............................11
   6.  Protocol State Machine....................................13
      6.1  Parameters............................................13
      6.2  Timers................................................15
      6.3  State Transition Diagram..............................15
      6.4  State Descriptions....................................15
   7.  Sending and Receiving VRRP Packets........................18
      7.1  Receiving VRRP Packets................................18
      7.2  Transmitting Packets..................................19
      7.3  Virtual MAC Address...................................19
   8.  Operational Issues........................................20
      8.1  ICMP Redirects........................................20
      8.2  Host ARP Requests.....................................20
      8.3  Proxy ARP.............................................20
   9.  Operation over FDDI and Token Ring........................21
      9.1  Operation over FDDI...................................21
      9.2  Operation over Token Ring.............................21
   10. Security Considerations...................................23
      10.1  No Authentication....................................23
      10.2  Simple Text Password.................................23
      10.3  IP Authentication Header.............................24
   11. Acknowledgments...........................................24
   12. References................................................24
   13. Authors' Addresses........................................25
   14. Full Copyright Statement..................................27

1.  Introduction

   There are a number of methods that an end-host can use to determine
   its first hop router towards a particular IP destination.  These
   include running (or snooping) a dynamic routing protocol such as
   Routing Information Protocol [RIP] or OSPF version 2 [OSPF], running
   an ICMP router discovery client [DISC] or using a statically
   configured default route.

   Running a dynamic routing protocol on every end-host may be
   infeasible for a number of reasons, including administrative
   overhead, processing overhead, security issues, or lack of a protocol
   implementation for some platforms.  Neighbor or router discovery



Knight, et. al.             Standards Track