Configuring Gratuitous Arp; Introduction To Gratuitous Arp - H3C S5120-SI Series Configuration Manual

Configuration procedure
Configure Switch
Create VLAN 10.
<Switch> system-view
[Switch] vlan 10
[Switch-vlan10] quit
Add interface GigabitEthernet 1/0/1 to VLAN 10.
[Switch] interface GigabitEthernet 1/0/1
[Switch-GigabitEthernet1/0/1] port access vlan 10
[Switch-GigabitEthernet1/0/1] quit
Create interface VLAN-interace 10 and configure its IP address.
[Switch] interface vlan-interface 10
[Switch-vlan-interface10] ip address 192.168.1.2 8
[Switch-vlan-interface10] quit
Configure a static ARP entry with IP address 192.168.1.1 and MAC address 00e0-fc01-0000. The
outgoing interface corresponding to the static ARP entry is GigabitEthernet 1/0/1 belonging to VLAN
10.
[Switch] arp static 192.168.1.1 00e0-fc01-0000 10 GigabitEthernet 1/0/1
View information about static ARP entries.
[Switch] display arp static
IP Address
192.168.1.1

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 device issuing the packet, the sender MAC address is the MAC address of
the device, 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.
•
Informing other devices of a change in its MAC address, 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 that no corresponding ARP entry exists in the cache.
Configuring gratuitous ARP
To configure gratuitous ARP:
Type: S-Static D-Dynamic
MAC Address VLAN ID
00e0-fc01-0000 10
Interface
GE1/0/1
16
Aging Type
N/A S