(Optional) Configuring Proxy ARP

When users access each other for the first time, they send ARP request packets. These packets are broadcast on Layer 2 networks. Proxy ARP can be configured to reduce the number of ARP broadcast packets.

Context

On an EVPN MPLS network, after a device receives an ARP request packet, it broadcasts the packet within a BD. If the device receives a large number of ARP request packets within a specified period and broadcasts these packets, excessive ARP request packets are forwarded on the EVPN MPLS network, consuming excessive network resources and causing network congestion. As a result, the network performance deteriorates, and user services are affected.

To address this problem, configure proxy ARP on the device. Proxy ARP allows a device to listen to a received ARP packet and generate an ARP snooping entry to record the source user information, including the packet's source IP address, source MAC address, and inbound interface. If proxy ARP is enabled on a device and an ARP request packet is received, the device preferentially responds to the request if an ARP snooping entry matches the user information in the ARP request.

Procedure

Run system-view
The system view is displayed.
(Optional) Run arp host ip-conflict-check period period-value retry-times retry-times-value
Host IP address conflict check is configured.
Run bgp { as-number-plain | as-number-dot }
The BGP view is displayed.
Run l2vpn-family evpn
The BGP-EVPN address family view is displayed.
Run peer { ipv4-address | group-name } advertise arp
ARP route advertisement is configured.
Run quit
The BGP view is displayed.
Run quit
The system view is displayed.
Run bridge-domain bd-id
The BD vew is displayed.
Run arp l2-proxy enable
Proxy ARP is enabled.
(Optional) Run arp l2-proxy timeout expire-time
An aging time is configured for ARP snooping entries.

Each ARP snooping entry has a life cycle, which is called the aging time. If an ARP snooping entry is not updated before its aging time expires, the entry will be deleted. If the corresponding ARP snooping entries are not released after a user goes offline, CPU resources are wasted and ARP snooping entries for new users cannot be properly generated. To resolve this problem, perform this step to set an aging time so that ARP snooping entries are updated regularly.
Perform the following operations as required:
- If a device needs to carry Layer 2 services, run the arp collect host enable command to enable the EVPN MPLS network to collect host information by BD.
- If a device needs to carry Layer 3 services or both Layer 2 and Layer 3 services, run the following commands:
  1. Run quit
    
    The system view is displayed.
  2. Run interface vbdif bd-id
    
    A VBDIF interface is created, and the VBDIF interface view is displayed.
  3. Run arp collect host enable
    
    The EVPN MPLS network is enabled to collect host information by VBDIF interface.
Run commit
The configuration is committed.