The arp detect-mode unicast command sets an interface to send an Address Resolution Protocol (ARP) aging detection packet in unicast mode.
The undo arp detect-mode unicast command restores the default setting.
By default, an interface sends the last ARP aging detection packet in broadcast mode, and the rest ARP aging detection packets are sent in unicast mode.
Usage Scenario
Before aging ARP entries, an interface sends ARP aging detection packets at the specified aging detection interval. If responses are received, the device updates ARP entries on the interface. If no response is received for some ARP entries within the specified interval, the device ages these ARP entries. The aging detection packet can be a unicast or broadcast packet. To configure an interface to send aging detection packets in unicast mode, run the arp detect-mode unicast command.
If a non-Huawei device receives an ARP aging detection packet with the destination MAC address as the broadcast address from a Huawei FW, but the IP-MAC mapping of the Huawei FW already exists in its ARP table, the non-Huawei device discards the ARP aging detection packet. Because the Huawei FW fails to receive a response to the ARP aging detection packet, the Huawei FW deletes the corresponding ARP entry. As a result, the traffic from the network side is interrupted. To resolve this problem, the Huawei FW must be configured to send ARP aging detection packets in unicast mode, and non-Huawei devices must be configured to respond to unicast ARP aging detection packets.
Precautions
If the IP address of the peer device remains the same but the MAC address changes frequently, configuring an interface to send ARP aging detection packets in broadcast mode is recommended.
If the MAC address of the peer device remains the same, the network bandwidth is insufficient, and the aging time of ARP entries is set to a small value, configuring an interface to send ARP aging detection packets in unicast mode is recommended.