[mif] Domain name issue in draft-stenberg-mif-mpvd-dns

Ray Bellis <ray@bellis.me.uk> Tue, 15 March 2016 10:26 UTC

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From: Ray Bellis <ray@bellis.me.uk>
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Date: Tue, 15 Mar 2016 10:26:37 +0000
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Subject: [mif] Domain name issue in draft-stenberg-mif-mpvd-dns
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Looking at section 3 of this draft, I have a problem with the
specification where it says that for e.g. a /64 the DNS lookup should be
for _pvd.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.x....ip6.arpa, and likewise the
/80 example (with 12 leading zeros).

Taking the /80 example, it would be impossible given this specification
to distinguish between a /80 where the bits between 64 and 80 were all
zeros and the corresponding /64 - they would both end up at the same
point in the ip6.arpa hierarchy.

In my opinion (and I do have some prior art in this space, see RFC 7216)
the "_pvd" label must be at the point in the ip6.arpa that presents the
same level as the prefix being queried for.  Any leading zeros below
that point (i.e. to the left in the domain name) MUST be omitted.

Hence in the /80 case, it would be _pvd.<20 labels>.ip6.arpa and in the
/64 case it would be _pvd.<16 labels>.ip6.arpa

Ray