Sean Doran <smd(_at_)ebone(_dot_)net> writes:
Unfortunately, IPv6's current addressing architecture makes it very
difficult to do this sort of traditional multihoming if one is not
a TLA.
This is not true. IPv6's TLA scheme has as its primary goal placing an
upper bound on the number of routing prefixes that are needed in the
core. I.e., a backbone provider is only required to maintain routes
for each individual TLA in order to have reachability to ALL
destinations. Contrast that with today's IPv4 where the number of
prefixes that need to be maintained in the DFZ in order to have global
reachability is more-or-less unbounded, so some prefixes are not
reachable from everywhere.
That doesn't mean that all or even any of these routes will be
optimal. An individual provider, may, maintain longer prefixes for
selected destinations in order to provide better contectivity, say, to
those willing to pay. Thus, traditional multihoming is still quite
possible, assuming the various ISPs that need to handle the routes
agree to do so. But the goal is to make such routes exceptions that
are value-add rather than are a fundamental requirement in order to
insure global reachability for all.
Thomas