    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]