Subject: [MMUSIC] RTSP session renegotiation

From: "valeria calcagni" <[email-masked]>
Date: Wed, 09 Aug 2006 10:31:35 +0000

Dear all,
I’m actually doing researches on how it would be possible to renegotiate an already established session when the characteristics of the link radio changes over time.

In RFC 2326 it’s stated that for fixed networks, a new SETUP request should be issued by the client for this purpose, can you confirm it?

It also stated that: “The server generates session identifiers in response to SETUP requests. If a SETUP request to a server includes a session identifier, the server MUST bundle this setup request into the existing session or return error 459 Aggregate Operation Not Allowed”, but this is not against with what is stated in section 12 regarding the usage of Session header:               ” Session    Rr     req.      all but SETUP, OPTIONS”?

Should in the scenario described above the new SETUP contain a new SDP body or only the Transport Header updated accordingly?

Talking about wireless environment, if the radio link characteristics change over time causing a renegotiation of the an already established session, which is the most appropriate message to use? SETUP or SET_Parameter? Are they two equivalent implementations?

I’d really appreciate if you can help me to find the correct answers to my questions.

Many thanks and best regards

Valeria Calcagni

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From: Kylin Wei <[email-masked]>
Date: Tue, 15 Aug 2006 14:01:13 +0800

Hi Valeria:

Follow is my notion. But please correct me if I'm wrong.

A client MAY issue a SETUP request for a stream that is already set

   up or playing in the session to change transport parameters, which a

   server MAY allow. If it does not allow changing of parameters, it

   MUST respond with error 455 (Method Not Valid in This State).

I think this new SETUP request should contain current session identifier and
other necessary information, not only Transport header.

Note: transport parameters for the media stream MUST only be set with the
SETUP command. 

Restricting setting transport parameters to SETUP is for the benefit of
firewalls. 

Kylin Wei 

  _____  

From: valeria calcagni [mailto:[email-masked]] 
Sent: Wednesday, August 09, 2006 6:32 PM
To: [email-masked]
Subject: [MMUSIC] RTSP session renegotiation

Dear all, 

Im actually doing researches on how it would be possible to renegotiate an
already established session when the characteristics of the link radio
changes over time. 

In RFC 2326 its stated that for fixed networks, a new SETUP request should
be issued by the client for this purpose, can you confirm it?   

It also stated that: The server generates session identifiers in response
to SETUP requests. If a SETUP request to a server includes a session
identifier, the server MUST bundle this setup request into the existing
session or return error 459 Aggregate Operation Not Allowed, but this is
not against with what is stated in section 12 regarding the usage of Session
header:                Session    Rr     req.      all but SETUP, OPTIONS?

Should in the scenario described above the new SETUP contain a new SDP body
or only the Transport Header updated accordingly? 

Talking about wireless environment, if the radio link characteristics change
over time causing a renegotiation of the an already established session,
which is the most appropriate message to use? SETUP or SET_Parameter? Are
they two equivalent implementations? 

Id really appreciate if you can help me to find the correct answers to my
questions.

Valeria Calcagni