RFC 1923 (rfc1923) - Page 2 of 3
RIPv1 Applicability Statement for Historic Status
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RFC 1923 RIPv1 Applicability Statement for Historic Status March 1996
that the mask used locally is the correct mask to apply for all
subnets of that network.
This has a number of effects.
1) RIPv1 can not be used with variable length subnetting. In the
presence of variable length subnetting it will consistently
misinterpret prefix lengths.
2) RIPv1 is difficult to use with supernetting. All CIDR supernets
must be exploded and advertised to RIPv1 as individual "natural"
classful advertisements.
3) Even when the networks running RIPv1 are themselves only subnetted
in fixed ways, if the remainder of the network has variable
subnetting then one must carefully make sure that RIPv1 does not
destroy the mask information when it passes through those subnets
running RIPv1. Put another way, co-existence with mutual
information exchange between RIPv1 and more advanced routing
protocols is problematic at best. Note that this applies even when
the other routing protocol is RIPv2.
4) The Internet will soon be making use of addresses which appear to
RIPv1 to be parts of Class A networks. Networks using RIPv1 may not
be able to reach all sites assigned the subsections of a single A.
2.2 Simple Distance Vector
RIPv1 is a simple distance vector protocol. It has been enhanced
with various techniques, including Split Horizon and Poison Reverse
in order to enable it to perform better in somewhat complicated
networks.
However, being a simple distance vector protocol, it will run into
difficulty. First and foremost, it will occasionally have to count to
infinity in order to purge bad routes. This delays the convergence
of routing. In order to keep this short, RIPv1 defines infinity as
16 hops. That means that networks with diameters larger than that
can not use RIP. Even getting close to that limit can cause
confusion for some implementations.
3.0 Conclusion
The recommendation of this Applicability statement is that if there
is reason to run RIP in a network environment, one should use RIPv2
(RFC 1723).
Halpern & Bradner Informational