Network Working Group G. Malkin
Internet Draft Xylogics
August 1992
RIP Version 2 Protocol Analysis
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 entering
RIP-2 into the standards track.
Status of this Memo
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts.
Internet Drafts are draft documents valid for a maximum of six
months. Internet Drafts may be updated, replaced, or obsoleted by
other documents at any time. It is not appropriate to use Internet
Drafts as reference material or to cite them other than as a "working
draft" or "work in progress."
Please check the I-D abstract listing contained in each Internet
Draft directory to learn the current status of this or any other
Internet Draft.
It is intended that this document will be submitted to the IESG for
consideration as a standards document. Distribution of this document
is unlimited.
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 the implementation experience.
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1. Protocol Documents
The RIP-2 protocol description is defined in Internet Draft "draft-
ietf-malkin-rip-04.txt". This draft specifies an update to the
"Routing Information Protocol" RFC 1058.
The RIP-2 MIB description is defined in Internet Draft "draft-ietf-
ripv2-mibext-02.txt". This draft has been approved by the Network
Management Area Directorate, and has passed two independent MIB
compiler checks.
2. Key Features
While RIP-2 shares the same basic algorythms 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.
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,
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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 missinterpret 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".
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
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who's identity cannot be disclosed at this time.
5. Security
Security issues are discussed in section 2.5.
6. Author's Address
Gary Scott Malkin
Xylogics, Inc.
53 Third Avenue
Burlington, MA 01803
Phone: (617) 272-8140
EMail: gmalkin@Xylogics.COM
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