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Re: [rtcweb] SIP Glare - Re: Minimal SDP negotiation mechanism

Hadriel Kaplan <HKaplan@acmepacket.com> Thu, 22 September 2011 14:38 UTC

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From: Hadriel Kaplan <HKaplan@acmepacket.com>
To: Tim Panton <tim@phonefromhere.com>
Thread-Topic: [rtcweb] SIP Glare - Re: Minimal SDP negotiation mechanism
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Date: Thu, 22 Sep 2011 14:40:33 +0000
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Subject: Re: [rtcweb] SIP Glare - Re: Minimal SDP negotiation mechanism
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On Sep 22, 2011, at 9:57 AM, Tim Panton wrote:

> At the risk of showing my ignorance - why are we expecting glare to be a problem? 
> To my mind glare only happens when you have a locked resource e.g. a busy line
> or number . Rtcweb does not contain either of those concepts, what's the resource
> that is being competed for here ?

The resource being competed for is SDP state/media info of the same session.  If both sides send a new SDP offer during the session at the same time, one side has to win.

One would think this would be ultra-rare, but in SIP it happens a lot in some deployments. 

-hadriel

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