Re: Last Call: <draft-ietf-6man-rfc4291bis-07.txt> (IP Version 6 Addressing Architecture) to Internet Standard

David Farmer <farmer@umn.edu> Thu, 23 February 2017 22:43 UTC

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From: David Farmer <farmer@umn.edu>
Date: Thu, 23 Feb 2017 16:43:51 -0600
Message-ID: <CAN-Dau0xpjB4Z8CgSfW0W7y4F_wnXNS+Ws1UNBC-YnBDrPiTjQ@mail.gmail.com>
Subject: Re: Last Call: <draft-ietf-6man-rfc4291bis-07.txt> (IP Version 6 Addressing Architecture) to Internet Standard
To: Lorenzo Colitti <lorenzo@google.com>
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Cc: 6man WG <ipv6@ietf.org>, IETF-Discussion Discussion <ietf@ietf.org>, draft-ietf-6man-rfc4291bis@ietf.org, 6man-chairs@ietf.org
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On Wed, Feb 22, 2017 at 10:16 PM, Lorenzo Colitti <lorenzo@google.com>;
wrote:
>
> Help he understand, then. There is widely-deployed code that assumes that
> the interface ID is 64 and does not work on anything other than 64 bit
> prefix lengths. Currently that code is correct on all unicast space. If you
> change RFC 4291, won't that code be incorrect?
>

OK, what if we said something like this;

   IPv6 unicast routing is based on prefixes of any valid length up to
   128 [BCP198]. However, all implementations of IPv6 are REQUIRED to
   support an IID length of 64 bits, other IID lengths are OPTIONAL.
   Subnet prefixes of /64 are RECOMMENDED for general purpose use,
   subnet prefixes of /127 are RECOMMENDED for point-to-point router
   links [RFC6164], other subnet prefix lengths are NOT RECOMMENDED,
   as their use could be incompatible with some implementations of IPv6.
   The rationale for the 64 bit boundary in IPv6 addresses can be found
   in [RFC7421].

I'd prefer other IID lengths to be RECOMMENDED for implementations, but I
can live with OPTIONAL.



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