* A closer look at Multicast Source Discovery Protocol
In a multicast network, sources and receivers register with their local rendezvous points to announce sessions and enable receivers to find content. Large multicast networks typically have several rendezvous points at different locations or domains. The trouble is, there’s no way for a rendezvous point to inform remote rendezvous points of all the sources it knows about.
Protocol extends reach of multicast
By Paul Gilbert
In a multicast network, sources and receivers register with their local rendezvous points to announce sessions and enable receivers to find content. Large multicast networks typically have several rendezvous points at different locations or domains.
The trouble is, there’s no way for a rendezvous point to inform remote rendezvous points of all the sources it knows about. If a user in the U.S. is looking for a source in its network that is multicasting live TV from Europe, it will go to its local rendezvous point. Because the European source is not registered with the user’s local rendezvous point, the user will not be able to access the session. The session will be available only to users who are local to the rendezvous point with which the source is registered.
Multicast Source Discovery Protocol (MSDP) solves this problem by enabling rendezvous points to inform each other about the sources that are known to them, thereby enabling access to these sources from any domain or location. An experimental protocol described in IETF RFC 3618, MSDP can be used between multicast domains and within domains.
A large organization with several rendezvous points located across the globe would use MSDP. In the scenario described above, the multicast session of live TV will begin in Europe and the source will register with its local rendezvous point. The local rendezvous point will then use MSDP to tell all the other rendezvous points on the network about the source and group that is using this session. When a user wants to receive this multicast feed, it will go to its local rendezvous point and request the data to be delivered from the source. The rendezvous point then will have the source and group addresses of this session and connect the user to the live TV.
For the full story, please go to:
https://www.nwfusion.com/news/tech/2004/120604techupdate.html?tu1
