From 4bfd864f10b68b71482b35c818559068ef8d5797 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Wed, 27 Nov 2024 20:54:24 +0100 Subject: doc: Add RFC documents --- doc/rfc/rfc1923.txt | 171 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 171 insertions(+) create mode 100644 doc/rfc/rfc1923.txt (limited to 'doc/rfc/rfc1923.txt') diff --git a/doc/rfc/rfc1923.txt b/doc/rfc/rfc1923.txt new file mode 100644 index 0000000..853f859 --- /dev/null +++ b/doc/rfc/rfc1923.txt @@ -0,0 +1,171 @@ + + + + + + +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. + +Abstract + + 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. + +1.0 Introduction + + 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. + +2.1 Classfulness + + 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 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 [Page 2] + +RFC 1923 RIPv1 Applicability Statement for Historic Status March 1996 + + + RIPv1 itself should only be used in simple topologies, with simple + reachability. It may be used by any site which uses fixed subnetting + internally, and either uses a default route to deal with external + traffic or is not connected to the global Internet or to other + organizations. + + RIPv1 may also be used as a local advertising technology if the + information to be used fits within its capabilities. + +4.0 Security Considerations + + RIPv1 includes no security functions. RIPv2 includes a mechanism for + authenticating the sender of the routing information. Sites which + are worried about the vulnerability of their routing infrastructure + and which feel they must run a RIP-like protocol should use RIPv2. + +5.0 Authors' Addresses + + Joel M. Halpern + Newbridge Networks Inc. + 593 Herndon Parkway Herndon, + VA 22070-5241 + + Phone: +1 703 708 5954 + EMail: jhalpern@newbridge.com + + + Scott Bradner + Harvard University + 1350 Mass Ave, Rm 813 + Cambridge MA 02138 + + Phone: +1 617 495 3864 + EMail: sob@harvard.edu + + + + + + + + + + + + + + + + + +Halpern & Bradner Informational [Page 3] + -- cgit v1.2.3