Huawei Quidway S6500 Series Operation Manual page 101

Operation Manual - Network Protocol
Quidway S6500 Series Ethernet Switches
If the device which sends the gratuitous ARP packet changed its hardware
address (probably, it turns off, has its interface card changed, and then reboots),
this packet can make old hardware address in the cache of other devices update
accordingly. For example, when a device receives a gratuitous ARP request
existing in the cache of the device from an IP address, then the sending hardware
address (such as Ethernet address) in the gratuitous ARP request needs to
update the content in the cache. The above operation must be done when a
device receives any gratuitous ARP request. ARP request is broadcast on the
network, so all hosts on the network must do this every time the ARP request is
sent.
Characteristics of gratuitous ARP packets:
The source and destination IP addresses are all native addresses, and the source
MAC address of the packet is native MAC address.
If another device receives a gratuitous ARP packet and finds out that the IP
address in the ARP packet conflicts with that of its own, it reports the conflict to the
device sending the gratuitous ARP packet.
2.3.2 Configuration Tasks
The configuration tasks of the gratuitous ARP are described in the following table:
Table 2-4 Configure gratuitous ARP
Sequence
number
1
2
Use the corresponding undo command to cancel the configuration.
2.3.3 Configuration Example
I. Network requirements
Enable gratuitous ARP packet learning on the switch Quidway A.
II. Configuration procedure
<QuidwayA> system-view
[QuidwayA] gratuitous-arp-learning enable
Configuration item
Enter system view
Enable ARP packet
learning
Huawei Technologies Proprietary
2-4
Chapter 2 ARP Configuration
Command
<Quidway> system-view
[Quidway]
gratuitous-arp-learning
enable
Description
—
Required