Re: draft-bourbaki-6man-classless-ipv6-00

[神明達哉 <[e-mail]>]

At Sat, 10 Jun 2017 13:44:34 -0700,
Fred Baker <[e-mail]> wrote:

> The only place it makes sense to me to talk about a specific length
> for an IID is with SLAAC; if a network is allocating addresses
> manually or using DHCP, they are in control and can do whatever they
> like - I dare you to stop them. But the IID is the part that is
> never a prefix - the last N bits of a /128, and by convention 64
> bits.

I'm afraid this is not really a correct description of the current
specification (if you're actually proposing to change the current
specifications on this, it would be more helpful if you could clarify
it's a proposal, not an explanation of the current spec).  It's
subtle, but I suspect this subtlety is part of the controversy we've
seen that should actually be unnecessary to have.

If the address is manually configured or configured using DHCPv6 with
some "prefix", that prefix is actually an on-link prefix and has
nothing to do with IID.  The IID length would still be defined by the
link-type specification, and since that should be consistent with the
addressing architecture, it *must* be 64 bits in practice.  But that
doesn't matter for actual operation - when the address is configured
manually or using DHCPv6, only on-link prefix matters in the actual
host behavior, and it can have an arbitrary length.

--
JINMEI, Tatuya