Re: Review of draft-ietf-tram-turn-server-discovery-08

Ralph Droms <rdroms.ietf@gmail.com> Thu, 01 September 2016 11:06 UTC

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Subject: Re: Review of draft-ietf-tram-turn-server-discovery-08
From: Ralph Droms <rdroms.ietf@gmail.com>
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Date: Thu, 1 Sep 2016 07:06:02 -0400
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To: Jari Arkko <jari.arkko@piuha.net>
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Cc: "draft-ietf-tram-turn-server-discovery.all@ietf.org" <draft-ietf-tram-turn-server-discovery.all@ietf.org>, "Review Area gen-art@ietf.org Team" <gen-art@ietf.org>, IETF discussion list <ietf@ietf.org>, "Tirumaleswar Reddy \(tireddy\)" <tireddy@cisco.com>
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RI just completed a quick review of draft-ietf-tram-turn-server-discovery-08.  The DNS Service Discovery section is much improved.  I have a couple of comments on the revised text:

I suggest adding a reference to the IANa "Service Name and Transport Protocol Port Number Registry", http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=Turn, as the source of the service  names "turn" and "turns".

While the example DNS records for "exampleco TURN Server" are technically correct, they would most likely be generated by the DNS-SD/mDNS library in a server, rather than appearing in a DNS server zone file somewhere.  For clarity, it might be better to use the unicast DNS versions of the DNS-SD records by substituting "example.com" for "local".

In my opinion, the details in section 5.1 are redundant with and (possibly) not identical to the specification in RFC 6762 and RFC 6763.  Specifically, Figure 1 includes a typo; there should be separate A/AAAA query and reply messages.  More generally, DNS-SD/mDNS servers may return the SRV, TXT, A and AAAA records in the first reply, as an optimization.  I think it would be better, in this document, to specify simply that TURN servers and clients use the message exchanges specified in those RFCs for TURN server discovery.  

- Ralph

> On Sep 1, 2016, at 4:05 AM, Jari Arkko <jari.arkko@piuha.net> wrote:
> 
> Ralph, Tiru — thanks for the updates and the review. I’ve looked at the change draft and I think it is fine now.
> 
> Jari
> 
>