Re: [DNSOP] [Doh] [EXTERNAL] Re: New I-D: draft-reid-doh-operator

Tony Finch <dot@dotat.at> Mon, 25 March 2019 16:13 UTC

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Date: Mon, 25 Mar 2019 16:13:19 +0000
From: Tony Finch <dot@dotat.at>
To: Ted Lemon <mellon@fugue.com>
cc: "doh@ietf.org" <doh@ietf.org>, "dnsop@ietf.org" <dnsop@ietf.org>
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Subject: Re: [DNSOP] [Doh] [EXTERNAL] Re: New I-D: draft-reid-doh-operator
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Ted Lemon <mellon@fugue.com>; wrote:
> On Mar 25, 2019, at 4:04 PM, Tony Finch <dot@dotat.at>; wrote:
> > If I understand it correctly, DTLS leaves MTU and fragmentation up to the
> > application protocol. The DNS has horrible packet size problems, so it
> > needs a lot more help than DTLS provides. QUIC is much better.
>
> Indeed.  My point was simply that this avoids ordering problems, just as
> QUIC does.  I suspect that it is worth having DNS-over-DTLS; QUIC is
> great, but based on what I’ve been seeing, quite a lot, and probably not
> appropriate for a lot of use cases where DNS-over-DTLS would do just
> fine.

It isn't so much ordering that is the problem, but not delaying answer B
when answer A suffers packet loss. I'm kind of curious about what the
relative trade-offs might be between DoQ and DoT with a decent SACK
implementation, when there is not much latency between the client and the
resolver. DNS-over-DTLS will need its own application layer retry
strategy. I kind of prefer the idea of DNS being able to re-use a good
off-the-shelf transport protocol rather than doing its own thing.

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>;  http://dotat.at/
Irish Sea: West or northwest 4 or 5. Smooth or slight. Showers. Good.