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Dynamic ARP entry
ARP automatically creates and updates dynamic entries. A dynamic ARP entry is removed when its aging
timer expires or the output interface goes down. In addition, a dynamic ARP entry can be overwritten by
a static ARP entry.
Static ARP entry
A static ARP entry is manually configured and maintained. It does not age out and cannot be overwritten
by any dynamic ARP entry.
Using static ARP entries enhances communication security. After a static ARP entry is specified, only a
specific MAC address is associated with the specified IP address. Attack packets cannot modify the
IP-to-MAC mapping. Thus, communications between devices are protected.
NOTE:
Usually ARP dynamically resolves IP addresses to MAC addresses, without manual intervention.
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.
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 a MAC address change.
Gratuitous ARP packets learning
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 only.
Configuring ARP entries
Displaying ARP entries
From the navigation tree, select
Network
>
ARP Management
. The
ARP Table
page appears, as shown
in
Figure 231
.
All ARP entries are displayed on the page.
Содержание Compaq Presario,Presario 1910
Страница 35: ...22 Figure 16 Sort display based on MAC address in the ascending order ...
Страница 54: ...41 Figure 27 Configuration finishes ...
Страница 70: ...57 Figure 42 Configuring idle timeout period 3 Set the idle timeout period for logged in users 4 Click Apply ...
Страница 98: ...85 Figure 67 Displaying the rate settings of ports ...
Страница 114: ...101 Figure 82 Port traffic statistics NOTE When the bandwidth utilization is lower than 1 1 is displayed ...
Страница 158: ...145 Field Description OutErrors Number of invalid packets sent through the interface ...
Страница 202: ...189 Figure 177 Creating a static MAC address entry ...
Страница 230: ...217 Figure 193 Configuring MSTP globally on Switch D ...
Страница 359: ...346 5 View the operation result in the Summary area Figure 316 IPv6 traceroute operation result ...