mld require-router-alert

Function

The mld require-router-alert command configures an interface to discard MLD messages without the Router-Alert option.

The undo mld require-router-alert command disables an interface from checking for the Router-Alert option in MLD messages.

By default, all received MLD messages are processed, including the MLD messages without the Router-Alert option.

Format

mld require-router-alert

undo mld require-router-alert

Parameters

None

Views

GE interface view, XGE interface view, MultiGE interface view, 25GE interface view, 40GE interface view, 100GE interface view, Eth-Trunk interface view, VLANIF interface view, loopback interface view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

Generally, a network device sends a message to the routing protocol module for processing only when the destination address of the message is a local interface address. Destination addresses of MLD messages are multicast addresses but not addresses of interfaces on multicast devices. Therefore, multicast devices do not send MLD messages to the MLD module for processing, and the MLD module cannot maintain group memberships.

The Router-Alert option in the IPv6 header of an MLD message solves this problem. If an MLD message contains the Router-Alert option, the device sends the message to the MLD module.

You can configure the device to accept only MLD messages with the Router-Alert option to improve MLD security.

Prerequisites

Layer 3 IPv6 multicast has been enabled using the multicast ipv6 routing-enable command in the system view.

Precautions

The function of the mld require-router-alert command is the same as that of the require-router-alert (MLD view) command used in the MLD view. The configuration in the MLD view is globally valid, whereas the configuration in the interface view takes effect only for the specified interface. The system prefers the configuration in the interface view. The configuration in the MLD view is used only when no configuration is performed in the interface view.

Example

# Configure VLANIF100 to discard MLD messages without the Router-Alert option.

<HUAWEI> system-view
[HUAWEI] multicast ipv6 routing-enable
[HUAWEI] interface vlanif 100
[HUAWEI-Vlanif100] mld require-router-alert

# Configure GE0/0/1 to discard MLD messages without the Router-Alert option.

<HUAWEI> system-view
[HUAWEI] multicast ipv6 routing-enable
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] undo portswitch
[HUAWEI-GigabitEthernet0/0/1] mld require-router-alert