Dear Michael; This is not the scenario that SSM was created for. SSM intends that each sourcing participant is its own source; in that case the SDP file is straightforward. What you are describing really sounds more like the older ASM service model or even the BiDir model.
(I am not saying that this cannot be done, just that this is not the intention behind SSM, which is why you will not find much help in the RFC's.) So, wouldn't it make more sense in a SSM scenario if you want to have a conference center for sending participants to create their own SDP files and forward them to to the center, which could then redistribute those files (so that other participants could join directly to each source they want) ? Regards Marshall Eubanks On Thu, 10 Feb 2005 20:36:11 +0100, Michael Gl�ssel <[EMAIL PROTECTED]> wrote: > Hi, > > SSM Scenario: > In a single-source multicast model (SSM), each participant sends its > media stream to a central point, using unicast. The central point then > redistributes the media to all participants using multicast. > > My question is how must a SDP be constructed if a participant wants to > join a conference. As the participant receives multicast he doesn't need > to provide a unicast contact in his offer. He only needs the answer from > the conference focus to know where to send his unicast stream and the > mulicast announcement. > So, is should really the offer/answer model be used for that scenario? > Or does the participant sends a blank SDP to the focus and the focus > consucts a SDP with the multicast media description and the unicast > media description for reception? > > I couln't find any information in the RFCs and IETF drafts. > > regards, Michael... > _______________________________________________ > Sip-implementors mailing list > [email protected] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
