Layer 3 Routing Commands 1192arp dynamicrenewUse the arp dynamicrenew command in Global Configuration mode toenable the ARP component to automatically renew dynamic ARP entrieswhen they age out. To disable the automatic renewal of dynamic ARP entrieswhen they age out, use the no form of the command.Syntaxarp dynamicrenewno arp dynamicrenewDefault ConfigurationThe default state is enabled.Command ModeGlobal Configuration modeUser GuidelinesWhen an ARP entry reaches its maximum age, the system must decidewhether to retain or delete the entry. If the entry has recently been used toforward data packets, the system will renew the entry by sending an ARPrequest to the neighbor. If the neighbor responds, the age of the ARP cacheentry is reset to 0 without removing the entry from the hardware. Traffic tothe host continues to be forwarded in hardware without interruption. If theentry is not being used to forward data packets, the system sends an ARPrequest to renew the entry. When an entry is not renewed, it is removed fromthe hardware and subsequent data packets to the host trigger an ARP request.Traffic to the host is lost until the router receives an ARP reply from the host.Gateway entries, and entries for a neighbor router, are always renewed. Thedynamic renew option only applies to host entries.The disadvantage of enabling dynamic renew is that once an ARP cache entryis created, that cache entry continues to take space in the ARP cache as longas the neighbor continues to respond to ARP requests, even if no traffic isbeing forwarded to the neighbor. If the ARP cache is full and a new host islearned, the oldest ARP cache entry is replaced with the new host entry.In anetwork where the number of potential neighbors is greater than the ARP
