The arp expire-time vlanif command sets the aging time of dynamic Address Resolution Protocol (ARP) entries on all VLANIF interfaces.
The undo arp expire-time vlanif command restores the default aging time of dynamic ARP entries on all VLANIF interfaces.
By default, the aging time of dynamic ARP entries on VLANIF interfaces is 1200s (20 minutes).
Usage Scenario
After receiving a unicast packet, a VLANIF interface searches the ARP table for the destination MAC address of the unicast packet, and searches the MAC table for the Layer 2 outbound interface based on the obtained destination MAC address. Then the Layer 2 outbound interface is allowed to forward the unicast packet. In specific scenarios, after entries in the MAC table are aged and not refreshed in time, the VLANIF interface fails to obtain the Layer 2 outbound interface and broadcasts the unicast packet in the VLAN.
To ensure service security, run the arp expire-time vlanif command to set the aging time for dynamic ARP entries on all VLANIF interfaces to a value smaller than the aging time for MAC entries. This prevents unicast packets from being broadcast due to a Layer 2 outbound interface mismatch.