arp collect host enable (Bridge domain view)

Function

The arp collect host enable command enables BGP EVPN or EVPN MPLS to collect host information by BD.

The undo arp collect host enable command disables BGP EVPN or EVPN MPLS from collecting host information by BD.

By default, BGP EVPN or EVPN MPLS is disabled from collecting host information by BD.

Format

arp collect host enable

undo arp collect host enable

Parameters

None

Views

Bridge domain view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
arp	write

Usage Guidelines

Usage Scenario

On an EVPN, when a user terminal accesses a Layer 2 device through a BD, the terminal sends an ARP request packet to the device. The packet is broadcast in the BD. If the device receives a large number of ARP request packets within a period and broadcasts the packets, many network resources are consumed, causing network congestion. As a result, network performance deteriorates and user services are affected. To resolve this issue, run the arp collect host enable command on each Layer 2 device. After the command is run, the Layer 2 devices use EVPN routes (MAC/IP routes) to synchronize learned user ARP information from one another and add the information to their local ARP snooping binding entries. The information contains the source IP and source MAC addresses.

When a Layer 2 gateway receives another ARP request packet, the gateway searches its local ARP snooping binding entries (including the locally listened entries and those synchronized from other gateways) for an entry that matches the packet's destination IP address.

If the matching entry exists, the gateway directly sends an ARP reply packet based on the entry.
If no matching entry exits, the gateway broadcasts the ARP request packet.

Prerequisites

Layer 2 proxy ARP has been enabled by running the arp l2-proxy enable command.

Example

# Enable BGP EVPN to collect host information by BD.

<HUAWEI> system-view
[~HUAWEI] bridge-domain 10
[*HUAWEI-bd10] arp l2-proxy enable
[*HUAWEI-bd10] arp collect host enable

# Enable BGP EVPN or EVPN MPLS to collect host information by BD.

<HUAWEI> system-view
[~HUAWEI] bridge-domain 10
[*HUAWEI-bd10] arp l2-proxy enable
[*HUAWEI-bd10] arp collect host enable