following two notes were copied from the cisco ios document,
1----
For networks that include links over X.25 packet switched networks (PSNs), the neighbor router configuration command can be used to defeat the split horizon feature. You can as an alternative explicitly specify the no ip split-horizon command in your configuration. However, if you do so you must similarly disable split horizon for all routers in any relevant multicast groups on that network.
2-------
In general, changing the state of the default for the ip split-horizon command is not recommended, unless you are certain that your application requires a change in order to properly advertise routes. If split horizon is disabled on a serial interface (and that interface is attached to a PSN), you must disable split horizon for all routers and access servers in any relevant multicast groups on that network.
My question is what is the influnce about the ip split-horizon command do with multicast?
