The mld-snooping require-router-alert command configures the switch to check the received MLD messages for the Router-Alert option and discard the MLD messages without the Router-Alert option.
The undo mld-snooping require-router-alert command restores the default configuration.
By default, the switch processes the received MLD messages regardless of whether the messages contain the Router-Alert option.
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 MLD messages contain the Router-Alert option and sends all the MLD messages to the upper-layer routing protocol. After the mld-snooping require-router-alert command is executed, the switch checks each MLD message for the Router-Alert option and discards those MLD messages without this option. This improves device performance, reduces cost, and enhances security of the upper-layer routing protocol.
Prerequisites
MLD snooping has been enabled globally using the mld-snooping enable command.
Precautions
If MLD snooping is disabled in the specified VLAN, the configuration succeeds but does not take effect until MLD snooping is enabled in the VLAN. To enable MLD snooping in a VLAN, run the mld-snooping enable command in the VLAN view.