Enabling PIM SM Snooping

Use PIM SM snooping only in topologies where multiple PIM sparse routers connect through a device. PIM SM snooping does not work on a PIM dense mode router which does not send join messages and traffic to PIM dense ports is stopped. A PIM SM snooping-enabled device displays a warning if it receives PIM dense join or prune messages.

The PIM SM traffic snooping feature assumes that the network has routers that are running PIM SM.
  1. Enter global configuration mode.
    device# configure terminal
  2. To enable PIM sparse snooping globally, enter the ip pimsm-snooping command.
    device(config)# ip pimsm-snooping
    Note: The device must be in passive mode before it can be configured for PIM SM snooping.