To add a permanent entry in the Address Resolution Protocol (ARP) cache, use the arp command in global configuration mode. To remove an entry from the ARP cache, enter the no form of this command.
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.
The software uses ARP cache entries to translate 32-bit IP addresses into 48-bit hardware addresses.
Because most hosts support dynamic resolution, you generally need not specify static ARP cache entries.
Static entries are permanent entries that map a network layer address (IPv4 address) to a data-link layer address (MAC address). If the alias keyword is specified when creating the entry, the interface to which the entry is attached will act as if it is the owner of the specified addresses, that is, it will respond to ARP request packets for this network layer address with the data link layer address in the entry.
The software does not respond to any ARP requests received for the specified IP address unless proxy ARP is enabled on the interface on which the request is received. When proxy ARP is enabled, the software responds to ARP requests with its own local interface hardware address.
To remove all nonstatic entries from the ARP cache, enter the clear arp-cache in EXEC mode.
The following is an example of a static ARP entry for a typical Ethernet host:
RP/0/RSP0/CPU0:router(config)# arp 192.168.7.19 0800.0900.1834 arpa