Concurrent Support for Multicast Routing and Snooping

Multicast routing and multicast snooping instances work concurrently on the same device. For example, you can configure PIM routing on certain virtual Ethernet (VE) interfaces and snooping on other VLANs. The limitation is that either multicast snooping or routing can be enabled on a VE interface or a VLAN, but not both. This is because all of the multicast data and control packets (IGMP, PIM) received on the snooping VLAN are handled by multicast snooping and do not reach the multicast routing component. Similarly, any multicast data or control packets received on a VE interface enabled with PIM routing are handled by the PIM routing component and are not seen by the IGMP or PIM snooping component.

The following considerations apply when configuring concurrent operation of Multicast Routing and Snooping.

  1. Either multicast snooping or routing can be enabled on a VE or VLAN, but not both.
  2. Snooping can be enabled globally by configuring the ip multicast command with either the active or passive keyword.
  3. The global snooping configuration is inherited by all current VLANs that are not enabled for multicast routing.
  4. The global snooping configuration is also inherited by all new VLANs. Enabling multicast routing on a newly created VLAN or VE automatically disables snooping on the VLAN or VE.
  5. When a VLAN-level snooping is configured, it is displayed.