The Address Resolution Protocol reference article from the English Wikipedia on 24-Jul-2004
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Address Resolution Protocol

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Internet protocol suite
Application layer FTP SMTP HTTP IRC ...
Transport layer TCP UDP SCTP ICMP ...
Network layer IP IPv6 ARP DHCP ...
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In computer networking using the internet protocol suite, the Address Resolution Protocol is a method for finding a host's Ethernet (MAC) address from its IP address. The sender broadcasts an ARP packet containing the Internet address of another host and waits for it (or some other host) to send back its Ethernet address. Each host maintains a cache of address translations to reduce delay and loading. ARP allows the Internet address to be independent of the Ethernet address but it only works if all hosts support it.

ARP is defined in RFC 826 .

The alternative for hosts that do not do ARP is to use a pre-configured mapping of IP addresses to MAC addresses.

Table of contents
1 Variants of the ARP protocol
2 See also
3 External links

Variants of the ARP protocol

ARP was not originally designed as an IP-only protocol, even though it is in practice used almost exclusively to resolve IP addresses to MAC addresses.

ARP can be used to resolve MAC addresses for many different Layer 3 protocols. ARP has also been adapted to resolve other kinds of Layer 2 addresses: for example, ATMARP is used to resolve ATM NSAP addresses in the Classical IP over ATM protocol.


See also

External links


This article was originally based on material from the Free On-line Dictionary of Computing and is used with permission under the GFDL.