H3C Technologies H3C WA3600 Series Access Points - Manual (Page 114)

101
ARP configuration
Overview
Introduction to ARP
The Address Resolution Protocol (ARP) is used to resolve an IP address into an Ethernet MAC address (or
physical address).
In an Ethernet LAN, a device uses ARP to resolve the IP address of the next hop to the corresponding
MAC address.
NOTE:
For more information about ARP, see H3C WA Series Access Points Layer 3 Configuration Guide.
Introduction to gratuitous ARP
Gratuitous ARP packets
In a gratuitous ARP packet, the sender IP address and the target IP address are the IP address of the
sending device, the sender MAC address is the MAC address of the sending device, and the target MAC
address is the broadcast address ff:ff:ff:ff:ff:ff.
A device sends a gratuitous ARP packet for either of the following purposes:
• Determine whether its IP address is already used by another device. If the IP address is already used,
the device will be informed of the conflict by an ARP reply.
• Inform other devices of the change of its MAC address.
Learning of gratuitous ARP packets
With this feature enabled, a device, upon receiving a gratuitous ARP packet, adds an ARP entry that
contains the sender IP and MAC addresses in the packet to its ARP table. If the corresponding ARP entry
exists, the device updates the ARP entry.
With this feature disabled, the device uses the received gratuitous ARP packets to update existing ARP
entries, but not to create new ARP entries.
Displaying ARP entries
Select Network > ARP Management from the navigation tree to enter the default ARP Table page shown
in Figure 101 . All ARP entries are displayed on the page.