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Re: [rtcweb] Minimal SDP negotiation mechanism

Magnus Westerlund <magnus.westerlund@ericsson.com> Tue, 20 September 2011 13:22 UTC

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Date: Tue, 20 Sep 2011 15:24:28 +0200
From: Magnus Westerlund <magnus.westerlund@ericsson.com>
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To: Harald Alvestrand <harald@alvestrand.no>
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Subject: Re: [rtcweb] Minimal SDP negotiation mechanism
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On 2011-09-19 18:59, Harald Alvestrand wrote:

> We need to handle glare - when one sends an OFFER and gets back an 
> OFFER, reply with SDP ERROR, enter a "glare" state, wait a bit, and send 
> out an offer again.
> 

I think that is a bad design for glare handling. I agree it needs to be
handled. I think the ICE version of glare handling could work pretty
well here. Any offer needs to include a random 32 bit number. If the
end-point receive an offer in relation to a peer-connection while it has
an outstanding offer then it compares these codes. Who ever has the
greatest numerical value wins and that offer is handled the other is
responded with an error stating GLARE. Thus there is no extra delay and
more clear resolution of the glare case.

Cheers

Magnus Westerlund

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