RFC 3178 (rfc3178) - Page 1 of 12
IPv6 Multihoming Support at Site Exit Routers
Alternative Format: Original Text Document
Network Working Group J. Hagino
Request for Comments: 3178 Research Laboratory, IIJ
Category: Informational H. Snyder
Vail Systems
October 2001
IPv6 Multihoming Support at Site Exit Routers
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2001). All Rights Reserved.
Abstract
The document describes a mechanism for basic IPv6 multihoming
support, and its operational requirements. Unlike currently-
practiced IPv4 multihoming, the technique does not impact the
worldwide routing table size, nor IGP (Interior Gateway Protocol)
routing table size in upstream ISPs. The mechanism can be combined
with more sophisticated (or complex) multihoming support mechanisms,
and can be used as a foundation for other mechanisms. The document
is largely based on RFC 2260 by Tony Bates.
1. Problem
Routing table size has been a major issue for both IPv4 and IPv6. As
IPv6 addresses are 4 times larger in bit width than IPv4, the routing
table size issue would have more serious negative effects on router
memory usage, as well as routing table lookup performance. To cope
with this problem, the IPv6 addressing architecture [Hinden, 1998] is
designed to take advantage of aggregated routing announcements to
reduce the number of routes in default-free zone. Also, 6bone
operation guideline [Rockell, 2000] (which is the currently-practiced
guideline for IPv6 network operation) suggests that ASes not announce
non-aggregatable announcements to the default-free zone, if there is
no special agreement with the peer.
In IPv4, a multihomed site uses either of the following techniques to
achieve better reachability:
Hagino & Snyder Informational