H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 188)

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Configuring ARP
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.
For more information about ARP, see "
About the H3C Access Controllers Web-Based 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 to perform the following tasks:
• Determines 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.
• Informs other devices of the change of its MAC address, if any.
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
From the navigation tree, select Network > ARP Management. The default ARP Table page appears, as
shown in
Figure 134 . All ARP entries are displayed on the page.