new to multicast configuration

[dennis.su]

Our University is looking to enable multicast/CGMP on our core router and several wan routers which connect to branches via leased circuits. I have been trialling dense mode in the main campus and now am in a position to extend it to branches. From the Q&A in this forum, it looks like spare-dense mode is a better choise than dense mode to reserve bandwidth. Is this correct? Another question is that, would spare mode increase the time to join and leave a group? Thanks in advance.

Dennis

[stphillips]

Sparse mode configurations will save you bandwidth based on the fact that dense mode uses the " flood and prune" method of propagating multicast traffic. What sparse mode gives you in bandwidth it takes away in the fact that you have t o configure Rendevous points for the multicast traffic to work across your network.

This will require a little more planning in that the RP should be close to the sources, and in multicast virtually anything could be a source.

Sparse mode does not increase the time to join and leave a group. Remember this is a function of IGMP. Depending on the version and implementation, the leaving of the group may even be faster. Since the routers all learn of the RP through the multicast groups 224.0.1.39, they will build trees for multicast rather quickly. I would not use dense mode unless it is a very small network. If you have newer switches, it is probaby better to use IGMP snooping than CGMP. Hope this helps.,