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

Brian E Carpenter <brian.e.carpenter@gmail.com> Fri, 03 March 2017 01:29 UTC

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Subject: Re: A proposal for draft-ietf-6man-rfc4291bis-07
To: "Manfredi, Albert E" <albert.e.manfredi@boeing.com>, David Farmer <farmer@umn.edu>, 6man WG <ipv6@ietf.org>
References: <CAN-Dau17q_BrUuzfvB1mLDt6p5UxYikphWaHpa8VQ2L-3kx-DA@mail.gmail.com> <a484b60f9d9b4fcea24dc320c550da2c@XCH15-06-11.nw.nos.boeing.com> <ee764408573b4db4b22e58c4ea5f289c@XCH15-06-11.nw.nos.boeing.com>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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Date: Fri, 3 Mar 2017 14:29:23 +1300
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On 03/03/2017 13:34, Manfredi, Albert E wrote:
> From: ipv6 [mailto:ipv6-bounces@ietf.org] On Behalf Of David Farmer
> 
>> 3. IIDs are REQUIRED to be 64 bits
> 
> 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.

Again, that breaks no running code, and it respects the architectural
statement that prefix_length + IID_length == 128, and the use of CIDR
routing and variable-length subnet masks.

    Brian