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Network Working Group                                          G. MalkinRequest for Comments: 1721                                Xylogics, Inc.Obsoletes:1387                                            November 1994Category: InformationalRIP Version 2 Protocol AnalysisStatus 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 inRFC 1722 [1].   The RIP-2 protocol description is defined inRFC 1723 [2].  This memo   obsoletesRFC 1388, which specifies an update to the "Routing   Information Protocol"RFC 1058 (STD 34).   The RIP-2 MIB description is defined inRFC 1724 [3].  This memo   obsoletesRFC 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 fromRFC 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 19942.1  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 toRFC 1388 implemented overRFC 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 insection 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 toRFC 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",RFC1722, 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",RFC1724, Xylogics, Inc., Cisco Systems, November 1994.Malkin                                                          [Page 3]

RFC 1721                     RIP-2 Analysis                November 19947.  Security Considerations   Security issues are discussed in sections2.4 and4.8.  Author's Address   Gary Scott Malkin   Xylogics, Inc.   53 Third Avenue   Burlington, MA 01803   Phone:  (617) 272-8140   EMail:  gmalkin@Xylogics.COMMalkin                                                          [Page 4]