Re: [Cbor] changes to draft-ietf-cbor-network-addresses-01.txt

Carsten Bormann <cabo@tzi.org> Mon, 08 March 2021 07:53 UTC

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From: Carsten Bormann <cabo@tzi.org>
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Date: Mon, 8 Mar 2021 08:53:00 +0100
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Subject: Re: [Cbor] changes to draft-ietf-cbor-network-addresses-01.txt
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I think prefixes and addresses are completely separate use cases.

There is rarely a point in suppressing trailing zeroes in an address.
We shouldn’t burden implementations to cater to this 0.4 % case (probably less in practice).

Prefixes are different, and they should indeed always be tail-cut.
(They are usually /64 or shorter, so there is a real win.)

We could imagine an alternate world where IIDs are carefully chosen so that actual addresses have as many trailing zeroes as possible.
But that’s not what happens today.  If we were to compress inner zero runs (as in “::”), we’d need to give the byte position where that happens (the length would be implied by the length of the remaining byte string).
I’m not proposing we cater to that.

Grüße, Carsten

(The /24 IPv4 example in the draft is wrong.)