An Address Resolution Protocol (ARP) Miss message is reported by a device to the upper-layer software when the device fails to find a matching ARP entry for IP datagram forwarding. After receiving the ARP Miss message, the upper-layer software generates a fake ARP entry and sends it to the device. The upper-layer software then sends an ARP request packet to the destination IP address of the ARP Miss message to request the destination MAC address. After receiving the ARP reply packet, the upper-layer software learns address information in the packet and sends the actual ARP entry to the device to replace the fake ARP entry. The device can then forward IP datagrams. If the device receives a large number of ARP Miss messages, these messages consume a lot of CPU resources, and the processing of other services is affected.
This problem can be solved by configuring an ARP Miss message rate limit on the device. After the ARP Miss message rate limit is configured, the device counts the number of received ARP Miss messages. If the number of ARP Miss messages received in a specified period exceeds an upper limit, the device does not process the excess ARP Miss messages.
Source IP addresses: This mode allows you to configure an ARP Miss message rate limit for all source IP addresses. This prevents user packets from consuming excessive CPU resources.
ARP Miss message rate limit is deployed on access and aggregation devices.
ARP Miss message rate limit helps prevent CPU exhaustion.