Subject: [Dime] Suresh Krishnan's Discuss on draft-ietf-dime-rfc4006bis-08: (with DISCUSS and COMMENT)

From: Suresh Krishnan <[email-masked]>
Date: Wed, 23 May 2018 13:55:26 -0700

Suresh Krishnan has entered the following ballot position for
draft-ietf-dime-rfc4006bis-08: Discuss

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DISCUSS:
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Section 8.38.

RFC5952 contains significant changes in text representation from RFC3513 and I
am concerned that there might be RFC4006 compliant implementations that will no
longer be legal with a MUST level use of RFC5952. e.g. Addresses with upper
case hex digits, with leading zeroes in 16 bit fields etc. Has the working
group considered this break in compatibility already in its discussions?

If it has, this text should still be finessed a bit because RFC5952
recommendations (even at the MUST level) are a SHOULD for senders with the
receivers being required to handle all possible legal formats as per RFC4291.
So at least the sender rules and receiver rules need to be written differently.

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COMMENT:
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Section 8.65

Any reason you are allowing encoding an IPv4 address as a IPv4-Mapped IPv6
Address while you can directly use address family 1 to encode it directly as an
IPv4 address? This allows for two different encodings for the same address.

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From: Dave Dolson <[email-masked]>
Date: Wed, 23 May 2018 22:03:28 -0400

Suresh,

Please see inline.

> https://datatracker.ietf.org/doc/draft-ietf-dime-rfc4006bis/
If I recall correctly, we did give this some thought. RFC 5952 was 
presumably done for a reason, due to flaws in previous descriptions of 
address format. Hence it is prudent to use the new requirements. 
Implementations are free to be liberal in what they receive, for 
backwards compatibility with RFC 4006.
So I think it's fair to say this standard requires use of RFC 5952 syntax.

Because IPv4-mapped IPv6 is a good idea. It allows coders to ignore IPv4 
and just develop for IPv6.
If we hadn't mentioned it explicitly, I think some people would have 
assumed it to be supported and others not.
So we had the choice of allowing it or prohibiting it. We chose to allow.

-Dave