D-Link DES-3550 Product Manual - Page 149

Gratuitous ARP Settings, Configuration > Layer 3 IP Networking &gt, Apply, Modify

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xStack® DES-3500 Series Layer 2 Stackable Fast Ethernet Managed Switch User Manual Gratuitous ARP Settings An ARP announcement (also known as Gratuitous ARP) is a packet (usually an ARP Request) containing a valid SHA (Sender Hardware Address) and SPA (Sender Protocol Address) for the host which sent it, with TPA (Target Protocol Address) equal to SPA. Such a request is not intended to solicit a reply, but merely update the ARP caches of other hosts which receive the packet. This is commonly done by many operating systems on startup, and helps to resolve problems which would otherwise occur if, for example, a network card had recently been changed (changing the IP address to MAC address mapping) and other hosts still had the old mapping in their ARP cache. To open the Gratuitous ARP Settings window, click Configuration > Layer 3 IP Networking > Gratuitous ARP Settings. Figure 6- 118. Gratuitous ARP Settings Table Once you have made the desired gratuitous ARP setting changes, click Apply. To modify a current entry, click the corresponding Modify button of the entry to be modified, revealing the following window to configure: Figure 6- 119. Gratuitous ARP Settings - Edit window The following fields can be set or viewed: Parameter Description Send on IPIF status This is used to enable/disable the sending of gratuitous ARP request packets while an IPIF up interface comes up. This is used to automatically announce the interface's IP address to other nodes. By default, the state is Enabled, and only one ARP packet will be broadcast. Send on Duplicate IP- Detected This is used to enable/disable the sending of gratuitous ARP request packets while a duplicate IP is detected. By default, the state is Enabled. Duplicate IP detected means that the system received an ARP request packet that is sent by an IP address that matches the system's own IP address. 134

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xStack
®
DES-3500 Series Layer 2 Stackable Fast Ethernet Managed Switch User Manual
134
Gratuitous ARP Settings
An ARP announcement (also known as Gratuitous ARP) is a packet (usually an ARP Request) containing a valid SHA (Sender
Hardware Address) and SPA (Sender Protocol Address) for the host which sent it, with TPA (Target Protocol Address) equal to
SPA. Such a request is not intended to solicit a reply, but merely update the ARP caches of other hosts which receive the packet.
This is commonly done by many operating systems on startup, and helps to resolve problems which would otherwise occur if, for
example, a network card had recently been changed (changing the IP address to MAC address mapping) and other hosts still had
the old mapping in their ARP cache.
To open the
Gratuitous ARP Settings
window, click
Configuration > Layer 3 IP Networking >
Gratuitous ARP Settings
.
Figure 6- 118. Gratuitous ARP Settings Table
Once you have made the desired gratuitous ARP setting changes, click
Apply
.
To modify a current entry, click the corresponding
Modify
button of the entry to be modified, revealing the following window to
configure:
Figure 6- 119. Gratuitous ARP Settings – Edit window
The following fields can be set or viewed:
Parameter
Description
Send on IPIF status
up
This is used to enable/disable the sending of gratuitous ARP request packets while an IPIF
interface comes up. This is used to automatically announce the interface’s IP address to other
nodes. By default, the state is
Enabled
, and only one ARP packet will be broadcast.
Send on Duplicate
IP- Detected
This is used to enable/disable the sending of gratuitous ARP request packets while a duplicate
IP is detected. By default, the state is
Enabled
. Duplicate IP detected means that the system
received an ARP request packet that is sent by an IP address that matches the system’s own
IP address.