H3C Technologies H3C S3100 Series Switches - Manual (Page 373)

Operation Manual – ARP
H3C S3100-52P Ethernet Switch Chapter 1 ARP Configuration
1-6
z
If a device finds that the IP addresses carried in a received gratuitous packet
conflict with those of its own, it returns an ARP response to the sending device to
notify of the IP address conflict.
By sending gratuitous ARP packets, a network device can:
z
Determine whether or not IP address conflicts exist between it and other network
devices.
z
Trigger other network devices to update its hardware address stored in their
caches.
The gratuitous ARP packet learning function:
When the gratuitous ARP packet learning function is enabled on a switch and the
switch receives a gratuitous ARP packet, the switch updates the existing ARP entry
(contained in the cache of the switch) that matches the received gratuitous ARP packet
using the hardware address of the sender carried in the gratuitous ARP packet. A
switch operates like this whenever it receives a gratuitous ARP packet.
1.2 ARP Configuration
ARP entries in an S3100-52P Ethernet switch can either be static entries or dynamic
entries, as described in Table 1-4.
Table 1-4
ARP entries
ARP entry Generation Method Maintenance Mode
Static ARP entry Manually configured Manual maintenance
Dynamic ARP entry Dynamically generated
ARP entries of this type age with
time. The aging period is set by
the ARP aging timer.
1.2.1 Adding a Static ARP Mapping Entry Manually
Table 1-5
Add a static ARP mapping entry manually
Operation Command Description
Enter system view
system-view
—
Add a static ARP
mapping entry
manually
arp static ip-address
mac-address
[ vlan-id
interface-type
interface-number
]
Required
By default, the ARP
mapping table is empty,
and the address mapping
entries are created
dynamically by ARP.