892 ARP CommandsARP AgingDynamic entries in the ARP cache are aged. When an entry for a neighborrouter reaches its maximum age, the system sends an ARP request to theneighbor router to renew the entry. Entries for neighbor routers shouldremain in the ARP cache as long as the neighbor continues to respond to ARPrequests. ARP cache entries for neighbor hosts are renewed more selectively.When an ARP cache entry for a neighbor host reaches its maximum age, thesystem checks if the cache entry has been used recently to forward datatraffic. If so, the system sends an ARP request to the entry's target IP address.If a response is received, the cache entry is retained and its age is reset to 0. Byenabling the dynamic renew option, the system administrator can configureARP to attempt to renew aged ARP entries regardless of their use forforwarding.If the system learns a new ARP entry but the hardware does not have space toadd the new ARP entry, the system attempts to remove entries that have notbeen used for forwarding recently. This action may create space for newentries in the hardware's ARP table.Commands in this ChapterThis chapter explains the following commands:arpUse the arp command in Global Configuration mode to create an AddressResolution Protocol (ARP) entry. Use the no form of the command to removethe entry.arp clear arp-cachearp cachesize clear arp-cache managementarp purge ip local-proxy-arparp resptime ip proxy-arparp retries show arparp timeout –
