Re: [rtcweb] Minimal SDP negotiation mechanism

Magnus Westerlund <magnus.westerlund@ericsson.com> Wed, 21 September 2011 08:20 UTC

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Date: Wed, 21 Sep 2011 10:22:36 +0200
From: Magnus Westerlund <magnus.westerlund@ericsson.com>
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To: Cullen Jennings <fluffy@cisco.com>
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Subject: Re: [rtcweb] Minimal SDP negotiation mechanism
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On 2011-09-20 21:58, Cullen Jennings wrote:
> 
> On Sep 20, 2011, at 7:24 AM, Magnus Westerlund wrote:
> 
>> 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
> 
> I think it has to be possible to gateway what happens here to what
> happens in SIP with glare - I suspect that more or less puts us on
> using the SIP glare mechanism.

I agree with that it needs to be possible to gateway with SIP. I will
think about if my proposal really is that difficult to interact with SIP.

And why, did you design such a poor glare handling algorithm for SIP? ;-)

Cheers

Magnus Westerlund

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