RIPng Protocol Applicability Statement (RFC2081)
Original Publication Date: 1997-Jan-01
Included in the Prior Art Database: 2019-Feb-16
Internet Society Requests For Comment (RFCs)
As required by Routing Protocol Criteria (RFC 1264), this report defines the applicability of the RIPng protocol within the Internet. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.
Network Working Group G. Malkin Request for Comments: 2081 Xylogics Category: Informational January 1997
RIPng Protocol Applicability Statement
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.
As required by Routing Protocol Criteria (RFC 1264), this report defines the applicability of the RIPng protocol within the Internet. This report is a prerequisite to advancing RIPng on the standards track.
1. Protocol Documents
The RIPng protocol description is defined in RFC 2080.
This report describes how RIPng may be useful within the new IPv6 Internet. In essence, the environments in which RIPng is the IGP of choice is comparable to the environments in which RIP-2 (RFC 1723) is used in the IPv4 Internet. It is important to remember that RIPng is a simple extrapolation of RIP-2; RIPng has nothing conceptually new. Thus, the operational aspects of distance-vector routing protocols, and RIP-2 in particular, within an autonomous system are well understood.
It should be noted that RIPng is not intended to be a substitute for OSPFng in large autonomous systems; the restrictions on AS diameter and complexity which applied to RIP-2 also apply to RIPng. Rather, RIPng allows the smaller, simpler, distance-vector protocol to be used in environments which require authentication or the use of variable length subnet masks, but are not of a size or complexity which require the use of the larger, more complex, link-state protocol.
The remainder of this report describes how each of the features of RIPng is useful within IPv6.
Malkin Informational [Page 1]
RFC 2081 RIP-2 Applicability January 1997
A goal in developing RIPng was to make the minimum necessary change to RIP-2 to produce RIPng. In essence, the IPv4 address was expanded into an IPv6 address, the IPv4 subnet mask was replaced with an IPv6 prefix length, the next-hop field was eliminated but the functionality has been preserved, and authentication was removed. The route tag field has been preserved. The maximum diameter of the network (the maximum metric value) is 15; 16 still means infinity (unreachable).
The basic RIP header is unchanged. However, the size of a routing packet is no longer arbitrarily limited. Because routing updates are never forwarded, the routing packet size is now determined by the physical media and the sizes of the headers which precede the routing data (i.e., media MTU minus the combined header lengths). The number routes which may be included in a routing update is the routing data length divided by the size of a routing entry.
The address field of a routing entry is 128 bits in length, expanded from the 32 bits available in RIP-2. This allows the RIP entry to carry an IPv6 prefix.
3.2 Prefix Length
The 32-bit RIP-2 subnet mask field is replaced by an 8-bit prefix length field. It allows the specific...