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 VSI.
The undo igmp-snooping require-router-alert command restores the default setting.
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 packets 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 with this option. This improves device performance, reduces cost, and enhances security of the upper-layer routing protocol.
Prerequisites
IGMP snooping has been enabled for VPLS using the igmp-snooping over-vpls enable command in the system view.
Precautions
The configuration takes effect only when IGMP snooping is enabled in the VSI using the igmp-snooping enable (VSI view) command.
# Configure the switch to discard the IGMP messages without the Router-Alert option in the IP header received from VSI company1.
<HUAWEI> system-view [HUAWEI] igmp-snooping enable [HUAWEI] igmp-snooping over-vpls enable [HUAWEI] vsi company1 [HUAWEI-vsi-company1] igmp-snooping enable [HUAWEI-vsi-company1] igmp-snooping require-router-alert