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

Ray Bellis <ray@bellis.me.uk> Tue, 15 March 2016 11:22 UTC

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To: Markus Stenberg <markus.stenberg@iki.fi>
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From: Ray Bellis <ray@bellis.me.uk>
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Date: Tue, 15 Mar 2016 11:22:08 +0000
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Cc: draft-stenberg-mif-mpvd-dns@ietf.org, mif@ietf.org
Subject: Re: [mif] Domain name issue in draft-stenberg-mif-mpvd-dns
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On 15/03/2016 11:08, Markus Stenberg wrote:
> Actually we considered it a feature and not a bug, i.e. subdelegation
> would still result in same PVD available. I am not sure your scheme
> would work with subdelegation though.

OK, I see that, but I still think you have a problem since:

   2001:0:0:0::/64

and

   2001:0:0:0:0::/80

and even:

   2001::/16

will end up at the same domain name.

> Given broad example, ISP has /40 for home users, but ultimately the
> prefix in use may be e.g. /64 (or even something more narrow). Having
> the _pvd.* in 'all' prefix lengths would be obviously available, or
> performing (up to 128) lookups with subsequently shorter/longer
> prefix lengths.
> 
> I am not sure how client would know to start lookups from /40, or
> from /56 assigned to a home, if the link has /64.

In RFC 7216 we took a "minimal" tree climbing approach, putting the
records at "common" LIR / RIR prefix boundaries of /64, /56, /48, or
/32.   Anything more would have angered the DNS Gods...

Is there no other way for the client to learn the size of the upstream
PD from which its /64 has been carved out?

Ray