Rockson Li (zhengyli) wrote: >Hi folks, > >Recently, I am confused on the identity of a RTP session. > >per RFC3550 > > RTP session: An association among a set of participants > communicating with RTP. ... A participant distinguishes > multiple RTP sessions by reception of different sessions using > <NOTE>different pairs of destination transport addresses,</NOTE> >where a pair > of transport addresses comprises one network address plus a pair > of ports for RTP and RTCP. > >So I draw the conclusion as follows, > >a RTP session is identified as a network plus two destination ports(RTP >&& RTCP port). > >therefore suppose two SIP UAs taking with each other on unicast UDP. > >UA1 >UA2 >IP: ip1 >IP: ip2 >RTP port: port1 >RTP port: port2 >RTCP port: port1+1 RTCP >port: port2+1 > > >so there will be two destination paris (ip1+ (port1,port1+1)), >(ip2+(port2,port2+1)) >so based on definition above, this should be thought as two RTP >sessions, shouldn't it? > >However, the same section of RFC3550. > ><snip> > For example, consider a three- > party conference implemented using unicast UDP with <NOTE>each > participant receiving from the other two on separate port >pairs.</NOTE> > If each participant sends RTCP feedback about data received from > one other participant only back to that participant, then the > conference is composed of three separate point-to-point RTP > sessions. ></snip> > >why there're only three RTP sessions, I think it should be six? >since "each participant receiving from the other two on separate port >pairs" >which means each pariticipant should listen on two separate port paris >for incoming RTP packets, >so there're two RTP sessions for each participant, and should be six for >three participants. > >Confunsed.... > +1. I'm also confused and still can't find the answer.
-- Regards, Evgeniy Khramtsov, ProcessOne. xmpp:[EMAIL PROTECTED] _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
