ipv6 nd multicast-suppress enable

Function

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

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

By default, NS multicast suppression is not enabled.

Format

ipv6 nd multicast-suppress { proxy-reply [ unknown-options-unicast ] | unicast-forward } [ mismatch-discard ] enable

undo ipv6 nd multicast-suppress { proxy-reply [ unknown-options-unicast ] | unicast-forward } [ mismatch-discard ] enable

undo ipv6 nd multicast-suppress enable

Parameters

Parameter	Description	Value
proxy-reply	When the destination address of an NS multicast message is not of the local host but can match a proxy ND entry on the local device, the device implements proxy ND and replies with an NA message.	-
unknown-options-unicast	When the destination address of an NS multicast message is not of the local host but can match a proxy ND entry on the local device, the device converts multicast streams to unicast streams for the packets carrying unrecognized options. By default, the device does not process unrecognized options in NS messages.	-
unicast-forward	When the destination address of an NS multicast message is not of the local host but can match a proxy ND entry on the local device, the device converts the NS multicast message to an NS unicast message and forwards the NS unicast message.	-
mismatch-discard	When the destination address of an NS multicast message is not of the local host and does not match a proxy ND entry on the local device, the device discards the NS multicast message. By default, the device replicates and forwards the NS multicast messages that do not match a proxy ND entry on the local device.	-

Views

Bridge domain view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
nd	write

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 proxy ND or 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

Before enabling NS multicast suppression, ensure that the encapsulation type of the Layer 2 sub-interface bound to the BD is not any of the following types:

Default type
Dot1q type. If no traffic behavior is configured on the EVC Layer 2 sub-interface, the sub-interface transparently transmits received packets without modifying them by default.
QinQ type. If no traffic behavior is configured on the EVC Layer 2 sub-interface, the sub-interface transparently transmits received packets without modifying them by default.

Before NS multicast suppression is enabled, if the encapsulation type of the EVC Layer 2 sub-interface bound to the BD is dot1q or QinQ:

If the encapsulation type of the EVC Layer 2 sub-interface bound to the BD is dot1q, you must run the rewrite pop single command on the EVC Layer 2 sub-interface to configure the EVC Layer 2 sub-interface to remove one VLAN tag from received packets.
If the encapsulation type of the EVC Layer 2 sub-interface bound to the BD is QinQ, you must run the rewrite pop double command on the EVC Layer 2 sub-interface to configure the EVC Layer 2 sub-interface to remove double VLAN tags from received packets.

Example

# Enable NS multicast suppression to allow the device to convert a multicast message to a unicast message and then forward the unicast message when the destination address of an NS multicast message is not of the local host but can match a proxy ND entry on the local device.

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

# Enable NS multicast suppression to allow the device to reply with an NA message when the destination address of an NS multicast message is not of the local host but can match a proxy ND entry on the local device.

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