[Users] SDP Parser

Michel Bensoussan michel at extricom.com
Tue Feb 20 14:23:08 CET 2007


"If the media goes directly from caller to callee I wonder why you need 
to know the bandwidth at all as the RTP packets may be out of your network."

I need to write a CAC (Call Admission Control) module for an 802.11 AP 
(Access Point).
The idea is to use a SIP Proxy to monitoring bandwith utilization 
according to codec, and allow or disallow new sessions, depending on 
resources.

Regards,
Michel.

Klaus Darilion wrote:
> Michel Bensoussan wrote:
>> Klaus Darilion wrote:
>>> Parsing the SDP does not give you the used codec as there may be 
>>> several codecs in the SDP and you do not know which codec is used by 
>>> the clients.
>> This is true for INVITE message but as I understand (but I'm not 
>> familiar with SIP), in the OK message, we can determine which codec 
>> is used. No?
>
> Not always. Often the 200 OK contains only one codec which will be 
> used by both parties. But I think there may also be asynchronous codec 
> (caller sends G711, callee sends G729).
>
>>> But for example you can use mediaproxy. Mediaproxy allows you to 
>>> retrieve the status of all current calls (codecs, bandwidth, ...)
>> Well, the mediaproxy module needs an external proxy server. So it 
>> seems to be too heavy for my needs.
>> The real time session statistics (from MediaProxy Server) will be 
>> very useful but I'm not sure it's a good idea to use the server it if 
>> I don't need the NAT traversal features.
>
> If the media goes directly from caller to callee I wonder why you need 
> to know the bandwidth at all as the RTP packets may be out of your 
> network.
>
> regards
> klaus
>
>>>
>>> regards
>>> klaus
>>>
>>> Michel Bensoussan wrote:
>>>> Hello
>>>> For each voice session I need to know the used codec (for bandwith 
>>>> calculation). For that I need to parse the SIP message body.
>>>> I didn't find in OpenSER such a functionality.
>>>> Is there a module that doing that?
>>>> Or maybe someone is working on it?
>>>> A suggestion for an open source?
>>>>
>>>> Thanks.
>>>>
>>>> Regards,
>>>> Michel.
>>>>
>>>>
>>>>
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>>>> http://openser.org/cgi-bin/mailman/listinfo/users
>>>
>>>
>
>




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