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Re: Allowing RTCIceServer to contain multiple URLs

From: Cullen Jennings (fluffy) <fluffy@cisco.com>
Date: Fri, 7 Jun 2013 19:12:36 +0000
To: Eric Rescorla <ekr@rtfm.com>
CC: Justin Uberti <juberti@google.com>, Martin Thomson <martin.thomson@gmail.com>, "public-webrtc@w3.org" <public-webrtc@w3.org>
Message-ID: <69F140AD-5CB7-4441-9CC8-9B67D6D4C8A6@cisco.com>

I"m not aware of srv having any issues for sip but I'm also unaware of any project to test it across a huge data set - but as you know I"m pretty skeptical about some the conclusions of some of the  published research on web and DNS.

On Jun 7, 2013, at 11:44 PM, "Eric Rescorla" <ekr@rtfm.com<mailto:ekr@rtfm.com>> wrote:




On Fri, Jun 7, 2013 at 4:11 AM, Cullen Jennings (fluffy) <fluffy@cisco.com<mailto:fluffy@cisco.com>> wrote:

On Jun 7, 2013, at 11:55 AM, Eric Rescorla <ekr@rtfm.com<mailto:ekr@rtfm.com>>
 wrote:

>
>
>
> On Thu, Jun 6, 2013 at 9:42 PM, Cullen Jennings (fluffy) <fluffy@cisco.com<mailto:fluffy@cisco.com>> wrote:
>
> On Jun 6, 2013, at 10:30 PM, Justin Uberti <juberti@google.com<mailto:juberti@google.com>> wrote:
>
> > The sections you are pointing to discuss the use of SRV to perform a lookup of a STUN or TURN server for a particular domain. How did you see this working with a TURN URI?
> >
> > That is, if the TURN URI specifies turn:foo.example.com<http://foo.example.com>, are you expecting the browser to do a SRV lookup of _turn._udp.foo.example.com<http://udp.foo.example.com>, _turn._tcp.foo.example.com<http://tcp.foo.example.com>, and _turns._tcp.foo.example.com<http://tcp.foo.example.com> - each of which will return a DNS name that will require another query to obtain the IP address?
> >
> >
>
> Yes. Pretty much. Keep in mind the server has no idea which will works so you are going to need to try the transports to see what works.
>
> A TURN client could lookup the UDP, start trying that  and in parallel go get DNS for tcp and test the TCP. If UPD (or TCP) does not work, it takes awhile to detect so parallel works out better.
>
> Do we have measurements on the SRV success rate from typical browser clients?

Any reason to think it might be less than say A records?

Yes. The Web doesn't work without A records but it works just fine w/o SRV.

I've heard fairly negative reports about TXT, so naturally this is a concern.

 -Ekr
Received on Friday, 7 June 2013 19:13:39 UTC

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