[asterisk-dev] RTP trunking - 58% savings on media bandwidth?

[Steve Underwood]

Will wrote:
> On Tue, Apr 7, 2009 at 3:56 AM,  <mctiew at yahoo.com> wrote:
>   
>> I search the mail archive and come across the idea of reducing RTP overhead :-
>>
>> http://www.mail-archive.com/asterisk-dev@lists.digium.com/msg35070.html
>>
>> I would like to mention the idea of muliplexing multiple calls trunking into the same destination thereby saving header, has already been implemented by some commercial entities. Natural Microsystems ( now part of Dialogic Intel ) has implemented such a scheme which they call it Trupacket (?). They never release their spec, but the implementation is only multiplexing the Media streams, and is de-coulpled from call control, meaning one could be using SIP call control but Trupacket media stream. This is contrast with IAX which include both call control and media stream.
>>     
>
>
> Is this method of trunking specified in a RFC somewhere?  IAX does
> trunking and has the ability to separate call control and the media
> stream in current implementations, IIRC.
>   
There have been several drafts for doing this. I think there is a 
current one right now. They never get followed through to RFC status, 
though. Its the same with merging RTP and RTCP on one port. It was 
allowed for in the way there originally assigned the reserved packet 
types, and the subject keeps coming up. Nobody takes it to completion, 
though. That said, a huge amount of the worlds RTP is carrying muxed 
calls in non-standard formats.

Steve