Design simple PIM networks where VLANs do not span several switches.
PIM relies on unicast routing protocols to perform its multicast forwarding. As a result, include in your PIM network design, a unicast design where the unicast routing table has a route to every source and receiver of multicast traffic, as well as a route to the RP router and Bootstrap router (BSR) in the network. Ensure that the path between a sender and receiver contains PIM-enabled interfaces. Receiver subnets are not always required in the routing table.
Use the following guidelines:
Ensure that every PIM-SM domain is configured with an RP, either by static definition or via BSR.
Ensure that every group address used in multicast applications has an RP in the network.
As a redundancy option, you can configure several RPs for the same group in a PIM domain.
As a load sharing option, you can have several RPs in a PIM-SM domain map to different groups.
In order to configure an RP to cover the entire multicast range, configure an RP to use the IP address of 224.0.0.0 and the mask of 240.0.0.0.
Configure an RP to handle a range of multicast groups by using the mask parameter. For example, an entry for group value of 224.1.1.0 with a mask of 255.255.255.192 covers groups 224.1.1.0 to 224.1.1.63.
In a PIM domain with both static and dynamic RP switches, you cannot configure one of the (local) interfaces for the static RP switches as the RP. For example, in the following scenario:
(static RP switch) Sw1 ------ Sw2 (BSR/Cand-RP1) -----Sw3
You cannot configure one of the interfaces on switch Sw1 as static RP because the BSR cannot learn this information and propagate it to Sw2 and Sw3. PIM requires that you consistently configure RP on all the routers of the PIM domain, so you can only add the remote interface Candidate-RP1 (Cand-RP) to the static RP table on Sw1.
If a switch needs to learn an RP-set, and has a unicast route to reach the BSR through this switch, you cannot enable or configure static RP on a switch in a mixed mode of candidate RP and static RP switches. For examples, see the following two figures.
