RIPv1 Applicability Statement for Historic Status (RFC1923)
Original Publication Date: 1996-Mar-01
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
RIP Version 1 [RFC-1058] has been declared an historic document. This Applicability statement provides the supporting motivation for that declaration. The primary reason, as described below, is the Classful nature of RIPv1.
Network Working Group J. Halpern
Request for Comments: 1923 Newbridge Networks
Category: Informational S. Bradner
RIPv1 Applicability Statement for Historic Status
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.
RIP Version 1 [RFC-1058] has been declared an historic document.
This Applicability statement provides the supporting motivation for
that declaration. The primary reason, as described below, is the
Classful nature of RIPv1.
RIP version 1 (RIPv1) (as defined by RFC 1058) was one of the first
dynamic routing protocols used in the internet. It was developed as
a technique for passing around network reachability information for
what we now consider relatively simple topologies.
The Internet has changed significantly since RIPv1 was defined,
particularly with the introduction and use of subnets and CIDR.
While RIPv1 is widely used in private networks, it can no longer be
considered applicable for use in the global Internet.
2.0 RIPv1 restrictions
RIPv1 has a number of restrictions and behaviors which restrict its
useability in the global Internet.
Chief among these is that it is a classful routing protocol. RIP
packets do not carry prefix masks. The prefix length is inferred
from the address. For non-local addresses, the prefix is always the
"natural" (classful) length. (e.g., 24 bits for a "Class C" network
address.) For networks to which a local interface exists, if the
interface is subnetted with some specific mask, then RIPv1 assumes
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"
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