Re: [MMUSIC] FW: New Version Notification for draft-reddy-mmusic-ice-happy-eyeballs-02.txt

"Tirumaleswar Reddy (tireddy)" <tireddy@cisco.com> Wed, 06 November 2013 09:56 UTC

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From: "Tirumaleswar Reddy (tireddy)" <tireddy@cisco.com>
To: Ari Keränen <ari.keranen@ericsson.com>
Thread-Topic: [MMUSIC] FW: New Version Notification for draft-reddy-mmusic-ice-happy-eyeballs-02.txt
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Date: Wed, 06 Nov 2013 09:56:41 +0000
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Cc: "mmusic@ietf.org" <mmusic@ietf.org>
Subject: Re: [MMUSIC] FW: New Version Notification for draft-reddy-mmusic-ice-happy-eyeballs-02.txt
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> -----Original Message-----
> From: Ari Keränen [mailto:ari.keranen@ericsson.com]
> Sent: Monday, November 04, 2013 9:25 PM
> To: Tirumaleswar Reddy (tireddy)
> Cc: mmusic@ietf.org
> Subject: Re: [MMUSIC] FW: New Version Notification for draft-reddy-mmusic-ice-
> happy-eyeballs-02.txt
> 
> 
> On Nov 4, 2013, at 6:00 AM, Tirumaleswar Reddy (tireddy) wrote:
> 
> >> -----Original Message-----
> >> From: Ari Keränen [mailto:ari.keranen@ericsson.com]
> >> Sent: Monday, November 04, 2013 12:10 PM
> >> To: Tirumaleswar Reddy (tireddy); mmusic@ietf.org
> >> Subject: Re: [MMUSIC] FW: New Version Notification for draft-reddy-mmusic-
> ice-
> >> happy-eyeballs-02.txt
> >>
> >> Hi,
> >>
> >> I think the algorithm starts to make sense, but how do you envision to
> >> choose the "N" and should there be a negotiation mechanism that ensures
> >> that both endpoints choose the same N ?
> >
> > I don't think there is any need to negotiate about "N" because it's only
> local prioritization of candidates. ICE agent can use Happy Eyeballs Extension
> for ICE algorithm independent of whether remote agent supports it or not.
> 
> Have you done an exercise (or better, implementation?) on how the candidate
> pairs would then look like? Since ICE uses MAX/MIN sorting of the pairs (see
> http://tools.ietf.org/html/rfc5245#appendix-B.5) simply having high priority
> on the other side may not give the results you want.

MAX/MIN logic used for calculating candidate-pair priority ensures that for a particular agent, a lower-priority candidate is never used until all higher-priority candidates have been tried. So even if the remote peer does not support Happy Eyeballs Extension algorithm, the ICE agent would start ICE connectivity checks based on the local prioritization and if IPv4 ICE connectivity is received by the remote peer then it would cause Triggered Checks for IPv4 candidate-pair. Hence IPv4 candidate-pair will be tested earlier even if remote peer does not Happy Eyeballs Extension algorithm. So effectively even if just one of the end points supports the algorithm, connectivity checks are optimized and should see better results. 

-Tiru.

> 
> 
> Cheers,
> Ari