Configuring Gratuitous Arp; Introduction To Gratuitous Arp; Displaying And Maintaining Arp - HP 4800G Series Configuration Manual

Configuring Gratuitous ARP

Introduction to Gratuitous ARP

A gratuitous ARP packet is a special ARP packet, in which the sender IP address and the target IP
address are both the IP address of the sender, the sender MAC address is the MAC address of the
sender, and the target MAC address is the broadcast address ff:ff:ff:ff:ff:ff.
A device implements the following functions by sending gratuitous ARP packets:
Determining whether its IP address is already used by another device. If the IP address is already
used, the device issuing the gratuitous ARP packet will be informed by an ARP reply of the conflict.
Informing other devices of its MAC address change so that they can update their ARP entries.
A device receiving a gratuitous ARP packet adds the information carried in the packet to its own
dynamic ARP table if it finds no corresponding ARP entry for the ARP packet in the cache.
Configuring Gratuitous ARP
Follow these steps to configure gratuitous ARP:
To do...
Enter system view
Enable the device to send
gratuitous ARP packets when
receiving ARP requests from
another network segment
Enable the gratuitous ARP
packet learning function

Displaying and Maintaining ARP

To do...
Display ARP entries in the
ARP table
Display the ARP entry for a
specified IP address
Display the ARP entries for
a specified VPN instance
Display the aging time for
dynamic ARP entries
Clear ARP entries from the
ARP table
For distributed devices
Use the command...
system-view
gratuitous-arp-sending
enable
gratuitous-arp-learning
enable
Use the command...
display arp [ [ all | dynamic | static ] [ slot
slot-number ] | vlan vlan-id | interface
interface-type interface-number ]
[ [ verbose ] [ | { begin | exclude | include }
regular-expression ] | count ]
display arp ip-address [ slot slot-number ]
[ verbose ] [ | { begin | exclude | include }
regular-expression ]
display arp vpn-instance
vpn-instance-name [ | { begin | exclude |
include } regular-expression | count ]
display arp timer aging
reset arp { all | dynamic | static | slot
slot-number | interface interface-type
interface-number }
1-6
Remarks
—
Required
By default, a device cannot
send gratuitous ARP packets
when receiving ARP requests
from another network segment.
Optional
Enabled by default.
Remarks
Available in any view
Available in any view
Available in any view
Available in any view
Available in user view