The igmp-snooping require-router-alert command configures the switch to drop the IGMP messages without the Router-Alert option in the IP header received from a VLAN.
The undo igmp-snooping require-router-alert command restores the default configuration.
By default, the switch does not check the Router-Alert option of IGMP messages and processes all the received IGMP messages, regardless of whether they carry the Router-Alert option in the IP header.
Usage Scenario
The Router-Alert option identifies the protocol messages that need to be processed by upper-layer routing protocols.
By default, the switch does not check whether IGMP messages contain the Router-Alert option and sends all the IGMP messages to the upper-layer routing protocol. After the igmp-snooping require-router-alert command is executed, the switch checks each IGMP message for the Router-Alert option and discards those IGMP messages without this option. This improves device performance, reduces cost, and enhances security of the upper-layer routing protocol
Prerequisites
IGMP snooping has been enabled globally using the igmp-snooping enable (system view) command.
Precautions
The configuration takes effect only after you run the igmp-snooping enable (VLAN view) command to enable IGMP snooping in the VLAN.