Hello!

I am building an RTP point to multipoint multiplexer. For this, when a 
packet comes in, I need to send it in to all receivers excepting the one 
which sent me the packet. It would be conveniant if I knew the ssrc of 
all receivers in order to do this but how do I know this before the 
packet is sent?

Hence, I am looking for some information which allows me to extract the 
SSRC of the receiver of an RTP session from the SDP answer. Is such 
information present in the SDP answer and where?   I sifted through the 
SDP offer/answer RFC but I dont seem to find any information about this 
issue.


Another way I can do this is to rely on IP address and port and make 
assumptions such apriori knowledge of IP and port where the sending 
socket will be bound ( this way I can look it up in the incoming RTP 
packet and avoid routing the packet back to the sender ). However, I 
dont find any information in the RTP RFC that obliges the sender to bind 
to any speicific IP address and port (only the receiver needs to bind to 
the IP and port in the SDP answer and not the sender). Please correct me 
if I am wrong in this assumption.

   
Thanks.

Ranga

-- 
M. Ranganathan 

Advanced Networking Technologies Division,
National Institute of Standards and Technology (NIST),
100 Bureau Drive, Stop 8920, Gaithersburg, MD 20899. 
tel:301 975 3664 , fax:301 590 0932 http://w3.antd.nist.gov/
Advanced Networking Technologies For the People!  


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