Subject: [MMUSIC] Muticast in RTSP.

From: "Pradip Gajjar" <[email-masked]>
Date: Sat, 7 Oct 2006 15:47:12 +0530

Hi All,

I have one doubt on multicast mechanism of transport in RTSP.
Please refer following example of SETUP request.

C->M: SETUP rtsp://live.example.com/concert/audio RTSP/1.0

      CSeq: 2

*      Transport: RTP/AVP;multicast    // Here it says it is multicast
session but client doesn't mention client port.*

M->C: RTSP/1.0 200 OK

      CSeq: 2

*      Transport:
RTP/AVP;multicast;destination=224.2.0.1;port=3456-3457;ttl=16
//here server responds with the port no.*

      Session: 0456804596

Now session is established but how multicast router would be able to send
the response to the client as client hasn't published it's port no in SETUP
request?

Rgrds,

Pradip Gajjar.
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---

From: "Andrew Large" <[email-masked]>
Date: Sun, 8 Oct 2006 12:58:23 -0700

Hmmm.  Maybe I'm not understanding your question properly, but here
goes...
 
Only one port pair is needed here.  When the client gets the setup
response, it creates a pair of UDP sockets, binds them to the given
addresses (including port), and joins the appropriate multicast group.
 
The multicast group join is what informs the router to forward the
packets to the client host.  The bind is what distributes the received
packets to the right sockets on the client host.

--
Andrew Large
[email-masked] 

-----Original Message-----
From: Pradip Gajjar [mailto:[email-masked]] 
Sent: Saturday, October 07, 2006 3:17 am
To: mmusic
Subject: [MMUSIC] Muticast in RTSP.

Hi All,

      CSeq: 2

      Transport: RTP/AVP;multicast    // Here it says it is multicast
session but client doesn't mention client port.

M->C: RTSP/1.0 200 OK

      CSeq: 2

      Transport:
RTP/AVP;multicast;destination=224.2.0.1;port=3456-3457;ttl=16   //here
server responds with the port no.

      Session: 0456804596

Now session is established but how multicast router would be able to
send the response to the client as client hasn't published it's port no
in SETUP request?

Rgrds,

Pradip Gajjar.