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Re: I-D Action:draft-ietf-v6ops-ipv6-cpe-router-03.txt
Hi Wes,
On Wed, 13 Jan 2010 09:42:29 -0600
"Wes Beebee (wbeebee)" <wbeebee@cisco.com> wrote:
> > I'm generally happy with the above text. I think the last sentence in
> > (b) would be slightly better if it said "greater than" rather than
> "different than".
>
> Actually, "different than" captures the scenario where the PD is a
> longer prefix than the hint indicated, in which case the CPE router may
> not be able to number all of the interfaces in such a way as to enable
> SLAAC. What to do in this case is unclear, and we leave it up to the
> vendor.
I'm not quite sure then I can see the value in this mechanism at all
then. I've seen this mechanism as a "Hey ISP, I really need this amount
of address space, otherwise I'm in trouble". If it's less
significant than that, and the CPE will have to deal with a smaller
prefix than requested (how is an interesting issue - interface
priorities?), then I'm not sure I can see that much value in what it
provides, other than some slightly useful information to the ISP about
how many downstream interfaces their customers' CPE has. That might be
useful to an ISP for addressing allocation purposes, although I'd think
they're being unnecessarily conservative if they're counting how many
individual subnets are required downstream of their customers' CPE.
Have I completely misunderstood the intent of this request/mechanism?
Thanks,
Mark.
>
> It also captures the case where the PD is a shorter prefix than the hint
> indicated, which is not really a problem for the CPE router.
>
> - Wes
>
>