Re: A proposal for draft-ietf-6man-rfc4291bis-07

Lorenzo Colitti <lorenzo@google.com> Fri, 03 March 2017 04:31 UTC

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From: Lorenzo Colitti <lorenzo@google.com>
Date: Fri, 3 Mar 2017 13:31:06 +0900
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Subject: Re: A proposal for draft-ietf-6man-rfc4291bis-07
To: Brian E Carpenter <brian.e.carpenter@gmail.com>
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On Fri, Mar 3, 2017 at 10:29 AM, Brian E Carpenter <
brian.e.carpenter@gmail.com>; wrote:

> > I think that RFC 4291 bis should not retain a constraint that has been
> applied so far, out of convenience, in the earliest stages of IPv6
> deployment.
>
> Agreed. And I think there are actually two things to say here:
>
> 3.1. Any IPv6-over-foo spec must specify a recommended IID length.
> 3.2. In the absence of such a spec, the recommended IID length is 64 bits.
>

I disagree that we should leave it up to IPv6-over-foo documents to specify
an IID length. If we wanted to make a statement along these lines, the
statement should be that the IID length is 64 bits unless otherwise
specified in an IPv6-over-foo document.

If were to end up making such a statement in this document, then this
document would need to formally update RFC 7934, some of whose conclusions
rest on the fact that IID lengths are currently required to be 64 bits
long, to say that IID lengths of 64 are RECOMMENDED for any network that
provides addresses to general-purpose hosts.

We would therefore have to say, in this document, that any IPv6-over-foo
document that specifies an IID shorter than 64 bits should either be
specifying a technology not used by general-purpose hosts, or should bear
the burden of explaining why the link layer it defines does not follow the
addressing best practices in RFC 7934.