Restrictions and guidelines: PIM snooping configuration
PIM snooping does not take effect on secondary VLANs. As a best practice, do not configure PIM snooping for secondary VLANs. For more information about secondary VLANs, see Layer 2—LAN Switching Configuration Guide.
Make sure the maximum size of a PIM join or prune message is smaller than the path MTU of devices connected to PIM snooping devices. Otherwise, fragmented PIM join or prune messages prevent PIM snooping from correctly forwarding multicast data. For more information about setting the maximum size of a join or prune message, see "Configuring PIM."
PIM snooping is supported only for PIM-SM and PIM-SSM. As a best practice, do not configure PIM snooping for PIM-DM and BIDIR-PIM. For more information about PIM, see "Configuring PIM."
After you configure PIM snooping for a VLAN, PIM snooping takes effect only on ports that belong to the VLAN.