D-Link DGS-1510 Series Reference Manual page 280

DGS-1510 Series Gigabit Ethernet SmartPro Switch CLI Reference Guide
A gratuitous ARP request packet is an ARP request packet where the source and the destination IP
address are both set to the IP address of the sending device and the destination MAC address is the
broadcast address.
Generally, a device use the gratuitous ARP request packet to discover whether the IP address is
duplicated by other hosts or to preload or reconfigure the ARP cache entry of hosts connected to the
interface.
Use the ip gratuitous-arps command to enable transmission of gratuitous ARP request. The device
will send out the packet when an IP interface becomes link-up or when the IP address of an interface
is configured or modified.
Use the ip gratuitous-arps dad-reply command to enable the transmission of gratuitous ARP
requests. The device will send out the packet while a duplicate IP address is detected.
Example
This example shows how to sending of gratuitous ARP messages.
Switch# configure terminal
Switch(config)# ip gratuitous-arps dad-reply
switch(config)#
32-3 arp gratuitous-send
This command is used to set the interval for regularly sending of gratuitous ARP request messages
on the interface. Use the no form of this command to disable this function on the interface.
arp gratuitous-send interval SECONDS
no arp gratuitous-send
Parameters
SECONDS
Default
By default, this option is disabled.
Command Mode
Interface Configuration Mode.
Command Default Level
Level: 12.
Usage Guideline
If an interface on the Switch is used as the gateway of its downlink devices and counterfeit gateway
behavior occurs in the downlink devices, administrators can configure to send gratuitous ARP request
messages regularly on this interface to notify that the Switch is the real gateway.
Example
This example shows how to enable the sending of gratuitous ARP messages.
Switch# configure terminal
Switch(config)# ip gratuitous-arps
switch(config)# interface vlan100
Switch(config-if)# arp gratuitous-send interval 1
Switch(config-if)#
Specifies the time interval to send the gratuitous ARP request
message in the range from 1 to 3600 seconds.
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