arp(6P)                         TCP/IP R4.11                         arp(6P)


NAME
       ARP - Address Resolution Protocol

DESCRIPTION
       ARP is a protocol that dynamically maps between the DARPA Internet
       and the hardware (Ethernet, token ring, or FDDI) addresses on a local
       network.  ARP is used by all the Ethernet and token ring interfaces
       and is not directly accessible to users.

       ARP caches Internet address mappings.  When a network interface
       requests a mapping for an Internet address not in the cache, ARP
       queues the message that requires the mapping so that it may be sent
       later, and broadcasts an ARP message on the associated network
       requesting the address mapping.  If a response is provided, the new
       mapping is cached and any queued messages are transmitted using the
       newly obtained hardware address.

       In addition to finding out Internet-Ethernet or Internet-token ring
       address pairs and storing these pairs in its table, ARP listens for
       ARP requests that are directed to the local machine.  If it receives
       a request, ARP replies with an ARP packet that contains the
       appropriate addressing information.

DIAGNOSTICS
       duplicate IP address!! sent from Ethernet address: 08:00:1B:35:26:74.

       ARP has discovered another host on the local network that claims to
       have the same Internet address as itself.  This is typically due to
       inconsistencies between host files (/etc/hosts) on various hosts on
       the network.

SEE ALSO
       arp(1M).


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