Subject: Re: [MMUSIC] RTSP and NATs

From: [email-masked]
Date: Wed, 12 Feb 2003 16:11:43 +0100

magnus you wrote:

>Also all the clients need to reside on the same port number
> which creates a multiplexing nightmare.

why? if the server _chooses_ its ports and puts them in the SDP ?

(anyway demultiplexing using SSRC was already discussed:
it is maybe not always a very good idea but it is doable...)

regards,

Philippe Gentric
Software Architect
Philips MP4Net
"philippe dot gentric at philips dot com"
http://www.platform4.philips.com

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From: Magnus Westerlund <[email-masked]>
Date: Wed, 12 Feb 2003 17:08:29 +0100

Hi Philippe,

Comments inline.

>why? if the server _chooses_ its ports and puts them in the SDP ?
Sorry, was not making clear that I assumed a known port which does not 
require signaling or spending extra RTTs. If you would send out the 
ports within the SDP then it gets simpler. However as discussed in 
another mail, co-locating is not a clean well engineered solution.

>it is maybe not always a very good idea but it is doable...)
We have discussed for symmetric RTP to use SSRC as an random identifier 
ensuring that it not another user that tries to hijack the session. With 
symmetric RTP it is after all the server that gives the client what 
ports to connect to. That allow the server to place a single user on 
each port pair. This way we can avoid doing SSRC multiplexing of 
different RTP sessions.

Best Regards

Magnus Westerlund 

Multimedia Technologies, Ericsson Research ERA/TVA/A
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