RIPv2: RIP Version 2 Protocol Analysis
An assessment of RIP-2 protocol features and early implementation results.
Malkin, G., "RIP Version 2 Protocol Analysis", RFC 1387, DOI 10.17487/RFC1387, January 1993, <https://www.rfc-editor.org/info/rfc1387>.
@misc{rfc1387,
series = {Request for Comments},
number = 1387,
howpublished = {RFC 1387},
publisher = {RFC Editor},
doi = {10.17487/RFC1387},
url = {https://www.rfc-editor.org/info/rfc1387},
author = {G. Malkin},
title = {{RIP Version 2 Protocol Analysis}},
pagetotal = 3,
year = 1993,
month = jan,
} RFC text
Contents
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.
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".
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
AI ELI5
On this page
§1Introduction
RIP version 2 extends the original Routing Information Protocol (RIP-1) from RFC 1058 with new features to make it more flexible and powerful. RFC 1388 defines the protocol itself, and RFC 1389 defines its MIB (management interface). RFC 1387 provides this analysis as required by the Routing Protocol Criteria (RFC 1264).
The analysis documents RIP-2's new capabilities and the implementation experience gained during development, serving as the technical review needed for protocol standardization.
RIP is a way routers share route information with each other. A new version adds helpful features. Before it could become official, someone had to check if it really works.
§2Key Features of RIP-2
RIP-2 adds six major improvements to RIP-1. Routing domains allow multiple independent RIP clouds to exist on the same physical network, enabling simple policy-based router grouping. External route tags carry information from other routing protocols (for example, AS numbers from BGP). Subnet masks allow variable-length masks, necessary for classless addressing (CIDR). Next-hop addresses let a router indicate better routes through other routers when multiple protocols are in use. Authentication protects RIP messages with passwords (extensible for stronger schemes). Multicasting reduces load on non-routing hosts by sending RIP packets to a multicast address instead of broadcasting to all.
RIP-2 adds six things: separate groups of routers, tags from other systems, flexible network masks, better path hints, password protection, and quieter messages. Each one solves a real problem from the original RIP.
§3Implementation Experience
At the time of publication, one nearly complete implementation existed: gated, written by Jeffrey Honig at Cornell University. It supported multicasting, subnet masks, limited authentication, next-hop, and limited routing domain support, with RIP-2 tools like ripquery available. The gated implementation had been tested against itself and RIP-1 implementations, though full support for subsumption rules, complete authentication, complete routing domains, and the MIB was still being developed.
A second complete implementation was under development by a vendor whose identity could not be disclosed at that time. This demonstrated that RIP-2 was implementable despite its added complexity.
Two companies were building RIP-2. One version (gated) was mostly working and was tested. The second was still in progress. This proved the new protocol could actually be built.