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rfc:rfc1387

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.

Malkin [Page 1] RFC 1387 RIP-2 Analysis January 1993

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".

Malkin [Page 2] RFC 1387 RIP-2 Analysis January 1993

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:  gmalkin@Xylogics.COM

Malkin [Page 3]

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