RIPv1 Applicability Statement for Historic Status (RFC1923)
Original Publication Date: 1996-Mar-01
Included in the Prior Art Database: 2019-Feb-12
Internet Society Requests For Comment (RFCs)
J. Halpern: AUTHOR [+1]
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. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.
Network Working Group J. Halpern Request for Comments: 1923 Newbridge Networks Category: Informational S. Bradner Harvard University March 1996
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
Halpern & Bradner Informational [Page 1]
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...