R2511-HP MSR Router Series Layer 3 - IP Services Configuration Guide(V5)

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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.
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 might 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:
Step 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.
3. Enable the device to send gratuitous
ARP packets upon receiving ARP
requests whose sender IP address
belongs to a different subnet.
gratuitous-arp-sending
enable
By default, a device does not send
gratuitous ARP packets upon
receiving ARP requests whose sender
IP address belongs to a different
subnet.
4. Enter interface view.
interface interface-type
interface-number
N/A
5. Enable periodic sending of gratuitous
ARP packets and set the sending
interval.
arp send-gratuitous-arp
[ interval milliseconds ]
By default, this feature is disabled.