Re: [MMUSIC] Question about RTSP proxy

Hi Jaehwan

well, for the above 2 examples, I am considering the second case. Two requests/responses on one TCP connection.

By the latest above example, I meant when the two SETUP requests for same resource transmitted through one TCP connection, server will have difficult to differentiate them.

By the example in my first email, I meant when two responses sent by one server through one TCP connection to Proxy, Proxy

may have difficult to differentiate them.

Surely, RTSP proxy, when implemented, can handle the problem by compromised solutions, e.g. CSeq. While proxy has to guarantee to generate different initial CSeq for each session by, e.g. ,comparing the current CSeq with those generated before. How many concurrent sessions can a proxy support, maybe 10000, then comparing CSeq would be a huge burden, because that will be a large order of magnitude.

Here is another assumption. Proxy send 2 RTSP requests to 2 servers, but, unfortunately, the 2 servers response the same session ID, by what mean will the proxy handle the following messages of the 2 sessions? Maybe take session ID and TCP connection together into consideration. Proxy has to do this every time it receive a message from the servers. That will be a huge workload. Besides, that will tie RTSP closely toTransport protocol, however RTSP 2.0 is in no way tied to a Transport protocol according to RFC2326.

Basically, I think the existing solutions to proxy can work but are very much compromised and result in complexity. We should find a easy and clear way to resolve the problem.

BTW,Multicast is just an example, the problem doesn't limit to multicast.

Regards

Yingjie Gu

From: Jaehwan Kim [mailto:jhkim at vidiator.com]
Sent: Wednesday, August 12, 2009 1:09 PM
To: Y.J. Gu; mmusic at ietf.org
Subject: RE: [MMUSIC] Question about RTSP proxy

Hi Yingjie,

On P<->S side, there would be two cases:

1/ using two different TCP sessions(typical case): Although the same cseq is found, Proxy should be able to handle different TCP sessions. And Proxy should map two different Client requests with these.

2/ using just one TCP session for two different RTSP sessions: Simple solution is to manage cseq well because proxy assign the value.

Which one do you consider?

And you may consider also non-permanent connection case, but still proxy could manage them and deliver Session ID generated from the server from my understanding.

Anyway it looks not multicast issue. And there are already many off-the-shelf RTSP proxy handle this matter without any problem.

Regards,

Jaehwan