Arp command, Cisco
From NetworkCommands
A command available on most Cisco platforms; used to create, modify or delete static ARP entries as well as specify use of ARP access-lists.
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Usage Syntax
The arp command is used to modify global, device-wide ARP configuration and interface specific configuration.
Configuration Context: global
arp ip_address mac_address [type] [interface]
The hardware address type parameter can be one of;
- arpa - ARPA (Ethernet) - this is the default type
- sap - SAP (HP's ARP type)
- smds - SMDS
- snap - SNAP (FDDI and TokenRing)
- srp-a - SRP (side A)
- srp-b - SRP (side B)
The optional interface parameter specifies the interface the specified MAC address is available through. See the usage notes below for more information.
Configuration Context: Interface
arp type
Valid values for type are:
- arpa
- frame-relay
- probe
- snap
arp timeout seconds - specify the ARP timeout for this interface in seconds using a value between 0 and 2147483. The default is 14400 (4hrs)
Usage Examples
arp 1.1.1.1 1234.ABCD.1234 arpa - create a static entry
no arp 1.1.1.1 1234.ABCD.1234 arpa - delete an existing static entry
arp timeout 1200 - specify an ARP timeout of 20 minutes for the interface
Usage Notes
Use the no form of this command to delete an ARP entry, static or dynamic
The MAC address should be specified in this format XXXX.XXXX.XXXX
The ARP timeout setting is interface specific
The default ARP timeout is 14400 seconds (4hrs)
Although an ARP timeout of less than 60 seconds can be specified, stale or timed-out ARP table entries are only removed from the ARP table once a minute
The Interface Parameter
The interface parameter is only significant if traffic is not routed out of the interface specified (because the destination host is on a locally attached network.) If the traffic is routed (because the destination host is on a remote network,) the MAC address of the next hop gateway is looked up and used, not the MAC address of the destination host.
Thus, only specify an interface if that interface is directly connected to the network the specified host resides on. (A route may point to an interface rather than a next hop but this still applies as the interface will, by definition, be attached to the local network the destination host is on.) A router will only look up the MAC address for a host if that host is on a directly connected network.
The following diagram provides and example of this:
Related Commands
Use the show arp command to view all dynamic and static ARP entries on a device
Use the clear arp-cache command to remove dynamic entries in a devices ARP table
Command Equivalents
The Windows command equivalent has the same name: arp command, Windows
The Linux command equivalent has the same name: arp command, Linux
Related Articles
The Linux ifconfig command displays the MAC address(es) of network interfaces installed in the system
The Windows getmac command displays the MAC address(es) of network interfaces installed in the system
Information on other Cisco commands 
Information on Vyatta commands 
Information on Extreme commands 
Information on Linux commands 
Information on F5 BigIP commands 
Information on Blue Coat SGOS commands
Information on Nokia IPSO commands
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