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Network Working Group G. Malkin Request for Comments: 1721 Xylogics, Inc. Obsoletes: 1387 November 1994 Category: Informational

                  RIP Version 2 Protocol Analysis

Status of this Memo

 This memo provides information for the Internet community.  This memo
 does not specify an Internet standard of any kind.  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.  This report is a prerequisite to
 advancing RIP-2 on the standards track.

Acknowledgements

 The RIP-2 protocol owes much to those who participated in the RIP-2
 working group.  A special thanks goes to Fred Baker, for his help on
 the MIB, and to Jeffrey Honig, for all his comments.

1. Protocol Documents

 The RIP-2 applicability statement is defined in RFC 1722 [1].

 The RIP-2 protocol description is defined in RFC 1723 [2].  This memo
 obsoletes RFC 1388, which specifies an update to the "Routing
 Information Protocol" RFC 1058 (STD 34).

 The RIP-2 MIB description is defined in RFC 1724 [3].  This memo
 obsoletes RFC 1389.

2. Key Features

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

 The significant change from RFC 1388 is the removal of the domain
 field.  There was no clear agreement as to how the field would be
 used, so it was determined to leave the field reserved for future
 expansion.

Malkin [Page 1]  RFC 1721 RIP-2 Analysis November 1994

2.1 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.

2.2 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.

2.3 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.

2.4 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.

2.5 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 are per-peer counters which provide the
 status of RIP-2 "neighbors".

Malkin [Page 2]  RFC 1721 RIP-2 Analysis November 1994

 The MIB was modified to deprecate the domain, which was removed from
 the protocol.  It has also been converted into version 2 format.

4. Implementations

 Currently, there are three complete implementations of RIP-2: GATED,
 written by Jeffrey Honig at Cornell University; Xylogics's Annex
 Communication server; and an implementation for NOS, written by Jeff
 White.  The GATED implementation is available by anonymous FTP from
 gated.cornell.edu as pub/gated/gated-alpha.tar.Z.  The implementation
 for NOS is available by anonymous FTP from ucsd.edu as
 /hamradio/packet/tcpip/incoming/rip2.zip.

 Additionally, Midnight Networks has produced a test suite which
 verifies an implementation's conformance to RFC 1388 implemented over
 RFC 1058.

 The author has conducted interoperability testing between the GATED
 and Xylogics implementations and found no incompatibilities.  This
 testing includes verification of protection provided by the
 authentication mechanism described in section 2.4.

5. Operational experience

 Xylogics has been running RIP-2 on its production systems for five
 months.  The topology includes seven subnets in a class B address and
 various, unregistered class C addresses used for dial-up access.  Six
 systems, in conjunction with three routers from other vendors and
 dozens of host systems, operate on those subnets.

 The only problem which has appeared is the reaction of some routers
 to Version 2 RIP packets.  Contrary to RFC 1058, these routers
 discard Version 2 packets rather than ignoring the fields not defined
 for Version 1.

6. References

 [1] Malkin, G., "RIP Version 2 Protocol Applicability Statement", RFC
     1722, Xylogics, Inc., November 1994.

 [2] Malkin, G., "RIP Version 2 - Carrying Additional Information",
     RFC 1723, Xylogics, Inc., November 1994.

 [3] Malkin, G., and F. Baker, "RIP Version 2 MIB Extension", RFC
     1724, Xylogics, Inc., Cisco Systems, November 1994.

Malkin [Page 3]  RFC 1721 RIP-2 Analysis November 1994

7. Security Considerations

 Security issues are discussed in sections 2.4 and 4.

8. Author's Address

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

 Phone:  (617) 272-8140
 EMail:  gmalkin@Xylogics.COM

Malkin [Page 4]