arp broadcast-suppress enable

Function

The arp broadcast-suppress enable command enables ARP broadcast suppression in a BD.

The undo arp broadcast-suppress enable command disables ARP broadcast suppression in a BD.

By default, ARP broadcast suppression is disabled in a BD.

Format

arp broadcast-suppress [ mismatch-discard ] enable

undo arp broadcast-suppress [ mismatch-discard ] enable

Parameters

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

Views

BD view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

If a gateway receives a large number of ARP request packets within a short period and broadcasts the ARP request packets in a BD, excessive ARP request packets are forwarded. As a result, excessive network resources are used, traffic congestion may occur, and network performance may decline. ARP broadcast suppression can effectively ease the pressure on the gateway in handling ARP packets. After receiving an ARP request packet, the gateway searches the ARP broadcast suppression table that contains the mapping between the IP address and MAC address of each destination device.

If a matching entry is found, the gateway replaces the broadcast MAC address in the received ARP request packet with the MAC address of the destination device, and then sends the request packet out through the interface matching the destination MAC address.
If no matching entry is found:
- The gateway broadcasts the ARP request packet in the BD if the mismatch-discard parameter is not set in the arp broadcast-suppress enable command.
- The gateway drops the ARP request packet if the mismatch-discard parameter is set in the arp broadcast-suppress enable command.

Precautions

When ARP broadcast suppression is configured in the VXLAN scenario with a large number of users and the ARP 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 ARP request packets. In the VXLAN scenario, the CAR for ARP 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 arp broadcast-suppress enable command is configured to enable ARP broadcast suppression in a BD and the broadcast-suppress enable command is configured to enable broadcast suppression in the BD, ARP broadcast suppression in the BD has a higher priority.

Example

# Enable ARP broadcast suppression in BD 10.

<HUAWEI> system-view
[HUAWEI] bridge-domain 10 
[HUAWEI-bd10] arp broadcast-suppress enable

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

<HUAWEI> system-view
[HUAWEI] bridge-domain 20
[HUAWEI-bd20] arp broadcast-suppress mismatch-discard enable