Configuring Gratuitous ARP 785
ARP Configuration
Example
Network requirements
■ Enable the ARP entry check.
■ Set the aging time for dynamic ARP entries to 10 minutes.
■ Set the maximum number of dynamic ARP entries that VLAN-interface 10 can
learn to 1000.
■ Add a static ARP entry, with the IP address being 192.168.1.1/24, the MAC
address being 000f-e201-0000, and the outbound port being GigabitEthernet
1/0/10 of VLAN 10.
Configuration procedure
<Sysname> system-view
[Sysname] arp check enable
[Sysname] arp timer aging 10
[Sysname] vlan 10
[Sysname-vlan10] port gigabitethernet 1/0/10
[Sysname-vlan10] quit
[Sysname] interface vlan-interface 10
[Sysname-vlan-interface10] arp max-learning-num 1000
[Sysname-vlan-interface10] quit
[Sysname] arp static 192.168.1.1 000f-e201-0000 10 gigabitethernet1/0/10
Configuring
Gratuitous ARP
Introduction to
Gratuitous ARP
A gratuitous ARP packet is a special ARP packet, in which the source IP address
and destination IP address are both the IP address of the sender, the source MAC
address is the MAC address of the sender, and the destination MAC address is a
broadcast address.
A device can implement the following functions by sending gratuitous ARP
packets:
■ Determining whether its IP address is already used by another device.
■ Informing other devices of its MAC address change so that they can update
their ARP entries.
A device receiving a gratuitous ARP packet can add the information carried in the
packet to its own dynamic ARP mapping 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… Use the command… Remarks
Enter system view system-view -
Enable the device to send
gratuitous ARP packets when
receiving ARP requests from
another network segment
gratuitous-arp-sending
enable
Required
By default, a device cannot
send gratuitous ARP packets
when receiving ARP requests
from another network
segment.
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