[h323plus] Symmetrical negotiation

Simon Horne s.horne at packetizer.com
Tue Jun 19 01:37:38 EDT 2012


There should be no need to alter the terminal capability set in h323plus
since they merge so you only use the common between the two devices so has
the same effect as waiting for what the remote has before sending your own
unless there is a compatibility issue then perhaps you don't want to
advertise certain known issue codecs. I have done this in the past by
creating an text exception list with PConfig and checking the device name
and adding/removing codecs from the TCS on OnLocalCapabilities.

 

The issue with the payload number is exactly the issue with SIP Generic
Payload Types are not generic they are fixed. In H.323 they are generic.
There really is no way to delay sending the OLC  besides it really won't
work anyway. The issue is H.323 OLC are sent for the media it wants to
RECEIVE so the receiver of the media (ie remote) makes the decision on the
payload. In SIP it's what is will be sending. This means you have no control
of the payload type in the OLC from the remote end.  So there are 2
solutions   1. Proxy the media  and correct the payload type number in the
SIP -> H.323 direction. OR. 2. Send the correct PayloadTypeNumber in the
OLCack to tell the remote what you actually will be sending. The problem not
all endpoints support this.

 

Simon

 

From: h323plus-bounces at lists.packetizer.com
[mailto:h323plus-bounces at lists.packetizer.com] On Behalf Of Diego Carvalho
Sent: 19 June 2012 05:07
To: h323plus at lists.packetizer.com
Subject: [h323plus] Symmetrical negotiation

 

Hi all, Does anyone know if there is a way to wait the remote endpoint's OLC
message before sending ours? I want to make the negotiation symmetric (have
same codecs) and also video payload type (e.g If remote sends pt = 96 in its
OLC I also want to send pt = 96 in my OLC). So that's why I need to wait
remote's OLC first. I appreciate any help. Thanks. 

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