Re: v6 vs gif

[Daniel Hagerty <hag%linnaean.org@localhost>]

Greg Troxel <gdt%ir.bbn.com@localhost> writes:

> I agree this is non-intuitive, and should certainly be documented, maybe
> in gif(4).  I had the impression v6 was always /64, but p2p links seem
> to have two /128s even if a whole /64 is assigned to the link.  If
> standards really do say that /128 is right, gif should deal with just
> addresses.

    Non /64 prefix lengths is contrary to du jure standard for
prefixes in 2000::/3.  (rfc4291 section 2.5.4)

    De facto reality is a completely different matter.  There is a
notable amount of operational resistence to /64 on p2p links.  RFC3627
documents a "considered harmful" configuration and points at a couple
of alternatives, including /128.