RFC 3178 (rfc3178) - Page 2 of 12
IPv6 Multihoming Support at Site Exit Routers
Alternative Format: Original Text Document
RFC 3178 IPv6 Multihoming Support at Site Exit Routers October 2001
o Obtain a portable IPv4 address prefix, and announce it from
multiple upstream providers.
o Obtain a single IPv4 address prefix from ISP A, and announce it
from multiple upstream providers the site is connected to.
Since the above two methodologies effectively inject additional
routes to the worldwide routing table, they have negative impact on
the worldwide routing table size issue. They also are not compatible
with current IPv6 operational practice.
This document provides a way to configure site exit routers and ISP
routers, so that the site can achieve better reachability from
multihomed connectivity, without impacting worldwide routing table
size issues. The technique uses multiple distinct IPv6 address
prefixes, assigned from multiple upstream ISPs. The technique uses
an already-defined routing protocol (BGP or RIPng) and tunneling of
IPv6 packets; therefore, this document introduces no new protocol
standard (the document describes how to operate the configuration).
This document is largely based on RFC 2260 [Bates, 1998] by Tony
Bates.
2. Goals and non-goals
The goal of this document is to achieve better packet delivery from a
site to the outside, or from the outside to the site, even when some
of the site exit links are down.
Non goals are:
o Choose the "best" exit link as possible. Note that there can be
no common definition of the "best" exit link.
o Achieve load-balancing between multiple exit links.
o Cope with breakage of any of the upstream ISPs.
3. Basic mechanisms
We use the technique described in RFC 2260 section 5.2 in our
configuration. To summarize, for IPv4-only networks, RFC 2260 says
that:
o We assume that our site is connected to 2 ISPs, ISP-A and ISP-B.
Hagino & Snyder Informational