You can configure a device to deny IGMP messages that do not contain the Router-Alert option and the device to send IGMP messages that contain the Router-Alert option.
To allow IGMP packets to be sent to the routing protocol layer, the Router-Alert option mechanism is used to mark protocol packets. If a packet contains the Router-Alert option, the packet must be sent to and processed by the routing protocol layer. After a multicast device receives an IGMP packet:
By default, the multicast device does not check the Router-Alert option and sends the IGMP packet to the routing protocol layer, irrespective of whether the IGMP packet contains the Route-Alert option.
If the multicast device is configured to check the Router-Alert option, the multicast device sends the IGMP packet to the routing protocol layer only if the packet contains the Route-Alert option.
IGMP message transmit and receive ends must have the same Router-Alert option configuration on the same network segment. If the two ends do not have the same Router-Alert option configuration, change the configuration on one end.
You can perform configurations either globally or on an interface.
Global configuration: takes effect on all interfaces.
Interface-specific configuration: takes precedence over the global configuration. If an interface-specific configuration is not available, the interface uses the global configuration.