Disabling an Interface from Learning ARP Entries
Context
If a user host connected to an interface initiates an ARP attack, ARP resources of the device may be exhausted. When a large number of dynamic ARP entries have been learned by an interface, disable the interface from learning more ARP entries on the gateway to ensure device security.
After dynamic ARP entry learning is disabled on an interface, the system will not automatically delete the ARP entries that were learned previously on this interface. Delete or retain these dynamic ARP entries as required.
If dynamic ARP entry learning is disabled on an interface, traffic forwarding may fail on this interface.
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 learning disable
The interface is disabled from learning ARP entries.
By default, an interface learns ARP entries dynamically.
- Run commit
The configuration is committed.
