The igmp require-router-alert command configures an interface to discard IGMP messages without the Router-Alert Option.
The undo igmp require-router-alert command disables an interface from checking for the Router-Alert Option in IGMP messages.
By default, the device does not check for the Router-Alert Option in IGMP messages and processes all the IGMP messages received on an interface.
GE interface view, XGE interface view, MultiGE interface view, 25GE interface view, 40GE interface view, 100GE interface view, Eth-Trunk interface view, GE sub-interface view, XGE sub-interface view, MultiGE sub-interface view, 25GE sub-interface view, 40GE sub-interface view, 100GE sub-interface view, Eth-Trunk sub-interface view, VLANIF interface view, loopback interface view
Usage Scenario
Generally, a network device sends a packet to the corresponding protocol module for processing only when the destination address of the packet is a local interface address. Destination addresses of IGMP packets are multicast addresses but not interface addresses of multicast devices. Therefore, multicast devices do not send IGMP packets to the IGMP module, and the IGMP module cannot maintain group memberships.
The Router-Alert option in the IP header of an IGMP message solves this problem. If an IGMP message contains the Router-Alert option, the device sends the message to the routing protocol module.
You can configure the device to accept only IGMP messages with the Router-Alert option to improve IGMP security.
Prerequisites
IP multicast routing has been enabled using the multicast routing-enable command.
Precautions
This command has the same function as the require-router-alert command used in the IGMP view. The configuration in the IGMP view takes effect for all interfaces, whereas the configuration in the interface view takes effect only for the specified interface. The configuration in the interface view takes precedence over the configuration in the IGMP view. The configuration in the IGMP view is used only when no configuration is performed in the interface view.
# Configure VLANIF100 to discard IGMP messages without the Router-Alert option.
<HUAWEI> system-view [HUAWEI] multicast routing-enable [HUAWEI] interface vlanif 100 [HUAWEI-Vlanif100] igmp require-router-alert
<HUAWEI> system-view [HUAWEI] multicast routing-enable [HUAWEI] interface gigabitethernet 0/0/1 [HUAWEI-GigabitEthernet0/0/1] undo portswitch [HUAWEI-GigabitEthernet0/0/1] igmp require-router-alert