Configuring the Aging Time of Temporary ARP Entries
Context
- In the aging time of temporary ARP entries:
- Before receiving an ARP reply packet, the device discards the IP packets matching the temporary ARP entry and does not generate ARP Miss messages.
- After receiving an ARP Reply packet, the device generates a correct ARP entry to replace the temporary entry.
- When temporary ARP entries age out, the device clears them. If no ARP entry matches the IP packets forwarded by the device, ARP Miss messages and temporary ARP entries are repeatedly generated.
You can limit the rate of ARP Miss messages by setting the aging time of temporary ARP entries. When a device undergoes an ARP Miss attack, you can extend the aging time of temporary ARP entries to reduce the frequency of triggering ARP Miss messages so that the impact on the device is minimized.
Procedure
- Run system-view
The system view is displayed.
- Run interface interface-type interface-number
The interface view is displayed.
- On an Ethernet interface, run undo portswitch
The interface is switched to Layer 3 mode.
By default, an Ethernet interface works in Layer 2 mode.
The mode switching function takes effect when the interface only has attribute configurations (for example, shutdown and description configurations). Alternatively, if configuration information supported by both Layer 2 and Layer 3 interfaces exists (for example, mode lacp and lacp system-id configurations), no configuration that is not supported after the working mode of the interface is switched can exist. If unsupported configurations exist on the interface, delete the configurations first and then run the undo portswitch command.
If many Ethernet interfaces need to be switched to Layer 3 mode, run the undo portswitch batch interface-type { interface-number1 [ to interface-number2 ] } &<1-10> command in the system view to switch these interfaces to Layer 3 mode in batches.
- Run arp fake timeout expire-time
The aging time of temporary ARP entries is set.
By default, the aging time of temporary ARP entries is 5 seconds.
- Run commit
The configuration is committed.
