About address allocating (IPv6, variable length SLA/prefixes?)

[ot@cisco.com (Ole Troan)]

> Architecturally, IPv6 has the equivalent of variable length subnet masks
> built in. There are really only two boundaries that are not flexible-
> the boundary between the format prefix and the rest of the address, and the
> /64 boundary. (The format prefix is in fact variable length, but it is
> architecturally defined.) So any IGP or EGP design needs to be fully flexible
> to the left of /64. Subnetting to the right of /64 would be tricky.

all IGP's and EGP's have to support all prefix-lengths. e.g you
want to announce host routes, /96 for NAT-PT, etc.
for that matter, the implementation(s) I know will let you create
subnets of whatever size you like.

/ot