Network Working Group                                          G. Malkin
Request for Comments: 1387                                Xylogics, Inc.
                                                           January 1993


                   RIP Version 2 Protocol Analysis

Status of this Memo

  This memo provides information for the Internet community.  It does
  not specify an Internet standard.  Distribution of this memo is
  unlimited.

Abstract

  As required by Routing Protocol Criteria (RFC 1264), this report
  documents the key features of the RIP-2 protocol and the current
  implementation experience.

Acknowledgements

  The RIP-2 protocol owes much to those who participated in the RIP-2
  Working Group of the Internet Engineering Task Force (IETF).  A
  special thanks goes to Fred Baker for his help on the MIB, and to
  Jeffrey Honig for the implementation experience.

1.  Protocol Documents

  The RIP-2 protocol description is defined in RFC 1388 [1].  This memo
  suggests an update to the "Routing Information Protocol" (RFC 1058)
  [3].  The RIP-2 MIB description is defined in RFC 1389 [2].

2.  Key Features

  While RIP-2 shares the same basic algorithms as RIP-1, it supports
  several new features.  They are: routing domains, external route
  tags, subnet masks, next hop addresses, and authentication.

2.1  Routing Domains

  Routing domains allow multiple RIP "clouds" to exist over the same
  physical network.  This is a feature requested by several members of
  the working group.  It allows simple policies to be constructed by
  grouping routers into domains which share routing information.







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2.2  External Route Tags

  The route tag field may be used to propagate information acquired
  from an EGP.  The definition of the contents of this field are beyond
  the scope of this protocol.  However, it may be used, for example, to
  propagate an EGP AS number.

2.3  Subnet Masks

  Inclusion of subnet masks was the original intent of opening the RIP
  protocol for improvement.  Subnet mask information makes RIP more
  useful in a variety of environments and allows the use of variable
  subnet masks on the network.  Subnet masks are also necessary for
  implementation of "classless" addressing, as the CIDR work proposes.

2.4  Next Hop Addresses

  Support for next hop addresses allows for optimization of routes in
  an environment which uses multiple routing protocols.  For example,
  if RIP-2 were being run on a network along with another IGP, and one
  router ran both protocols, then that router could indicate to the
  other RIP-2 routers that a better next hop than itself exists for a
  given destination.

2.5  Authentication

  One significant improvement RIP-2 offers over RIP-1, is the addition
  of an authentication mechanism.  Essentially, it is the same
  extensible mechanism provided by OSPF.  Currently, only a plain-text
  password is defined for authentication.  However, more sophisticated
  authentication schemes can easily be incorporated as they are
  defined.

2.6  Multicasting

  RIP-2 packets may be multicast instead of being broadcast.  The use
  of an IP multicast address reduces the load on hosts which do not
  support routing protocols.  It also allows RIP-2 routers to share
  information which RIP-1 routers cannot hear.  This is useful since a
  RIP-1 router may misinterpret route information because it cannot
  apply the supplied subnet mask.

3.  RIP-2 MIB

  The MIB for RIP-2 allows for monitoring and control of RIP's
  operation within the router.  In addition to global and per-interface
  counters and controls, there is are per-peer counters which provide
  the status of RIP-2 "neighbors".



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4.  Implementations

  Currently, there is one nearly complete implementation of RIP-2.  A
  "gated" implementation is now available with RIP-2, written by
  Jeffrey Honig at Cornell University.  It may be acquired by anonymous
  FTP from gated.cornell.edu as pub/gated/gated-alpha.tar.Z.  It
  implements multicasting, subnet masks, limited authentication, next-
  hop, and limited routing domain support.  A RIP-2 version of ripquery
  is also available.  The "gated" implementation does not yet support
  full subsumption rules, full authentication, full routing domains,
  and the MIB.  It has been tested against itself and various RIP-1
  implementations.

  A second, complete implementation is under development by a vendor
  who's identity cannot be disclosed at this time.

5. References

  [1] Malkin, G., "RIP Version 2 - Carrying Additional Information",
      RFC 1388, Xylogics, Inc., January 1993.

  [2] Malkin, G., and F. Baker, "RIP Version 2 MIB Extension", RFC
      1389, Xylogics, Inc., Advanced Computer Communications, January
      1993.

  [3] Hedrick, C., "Routing Information Protocol", RFC 1058, Rutgers
      University, June 1988.

6.  Security Considerations

      Security issues are discussed in section 2.5.

7.  Author's Address

      Gary Scott Malkin
      Xylogics, Inc.
      53 Third Avenue
      Burlington, MA 01803

      Phone:  (617) 272-8140
      EMail:  [email protected]










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