ipv6 nd multicast-suppress enable

Function

The ipv6 nd multicast-suppress enable command enables NS multicast suppression in a BD.

The undo ipv6 nd multicast-suppress enable command disables NS multicast suppression in a BD.

By default, NS multicast suppression is disabled in a BD.

Format

ipv6 nd multicast-suppress [ mismatch-discard ] enable

undo ipv6 nd multicast-suppress [ mismatch-discard ] enable

Parameters

Parameter	Description	Value
mismatch-discard	Indicates that the device drops NS packets that do not match any entries in the NS multicast suppression table.	-

Views

BD view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

When a network device receives an NS message to implement address resolution, the device forwards the NS message within its own BD. This NS message is received only by the nodes with the last 24 bits the same as the multicast address. If a device receives a large number of NS messages within a specified period, forwarding these NS messages uses excessive network resources and leads to network congestion and deteriorated network performance. As a result, user services are affected.

To resolve this problem, run the ipv6 nd multicast-suppress enable command to enable NS multicast suppression. With NS multicast suppression enabled, upon receipt of an NS message, a device checks whether the NS message contains information about the end user. If so, the device simply implements converts multicast streams to unicast streams. If not, the device forwards the NS message based on the original process. This reduces or suppresses message flooding occurred during address resolution.

Precautions

When NS multicast suppression is configured in the VXLAN scenario with a large number of users and the NS packets received by the gateway exceeds the committed access rate (CAR), run the car packet-type vpls-arp cir cir-value [ cbs cbs-value] command to adjust the CAR of the NS request packets. In the VXLAN scenario, the CAR for NS request packets is the same as that for vpls-arp packets. You can run the display cpu-defend configuration command to query the CAR. If the central processor CAR (CPCAR) is adjusted to an improper value, network services are affected. To adjust the CPCAR for packets, contact Huawei technical support.
If the ipv6 nd multicast-suppress enable command is configured to enable NS multicast suppression in a BD and the multicast-suppress enable command is configured to enable multicast suppression in the BD, NS multicast suppression in the BD has a higher priority.

Example

# Enable NS multicast suppression in BD 10.

<HUAWEI> system-view
[HUAWEI] bridge-domain 10 
[HUAWEI-bd10] ipv6 nd multicast-suppress enable

# Enable NS multicast suppression in BD 20 and configure the switch to discard ARP request packets if no matching entry is found in the NS multicast suppression table.

<HUAWEI> system-view
[HUAWEI] bridge-domain 20
[HUAWEI-bd20] ipv6 nd multicast-suppress mismatch-discard enable