F3215-HP Load Balancing Module Network Management Configuration Guide-6PW101

The master router of a VRRP group can periodically send gratuitous ARP packets to the hosts on the

local network, so that the hosts can update local ARP entries and avoid using the virtual IP address

of the VRRP group.

If the virtual IP address of the VRRP group is associated with a virtual MAC address, the sender

MAC address in the gratuitous ARP packet is the virtual MAC address of the virtual router. If the

virtual IP address of the VRRP group is associated with the real MAC address of an interface, the

sender MAC address in the gratuitous ARP packet is the MAC address of the interface on the

master router in the VRRP group.

• Update MAC entries of devices in the VLANs having ambiguous VLAN termination configured.

In VRRP configuration, if ambiguous VLAN termination is configured for many VLANs and VRRP

groups, interfaces configured with VLAN termination need to be disabled from transmitting

broadcast/multicast packets and a VRRP control VLAN needs to be configured so that VRRP

advertisements can be transmitted within the control VLAN only. In such cases, you can enable

periodic sending of gratuitous ARP packets containing the VRRP virtual IP address, and the primary

IP address or a manually configured secondary IP address of the sending interface on the

subinterfaces. In this way, when a VRRP failover occurs, devices in the VLANs having ambiguous

VLAN termination configured can use the gratuitous ARP packets to update their corresponding

MAC entries in time.

For more information about VRRP, see High Availability Configuration Guide.

Configuration guidelines

Follow these guidelines when you configure gratuitous ARP:

• You can enable periodic sending of gratuitous ARP packets on a maximum of 1024 interfaces.

• Periodic sending of gratuitous ARP packets takes effect only when the link of the enabled interface

goes up and an IP address has been assigned to the interface.

• If you change the interval for sending gratuitous ARP packets, the configuration is effective at the

next sending interval.

• The frequency of sending gratuitous ARP packets may be much lower than the sending interval set

by the user if this function is enabled on multiple interfaces, if each interface is configured with

multiple secondary IP addresses, or if a small sending interval is configured when the previous two

conditions exist.

Configuration procedure

To configure gratuitous ARP:

Ste

Command

Remarks

1. Enter system view.

system-view N/A

2. Enable learning of gratuitous

ARP packets.

gratuitous-arp-learning enable

Optional.

Enabled by default.