Overview of ARP
This section describes the definition and purpose of ARP.
Definition
Address Resolution Protocol (ARP) is used to map IP addresses to MAC addresses.
Purpose
On a local area network (LAN), before sending data, a host or a Layer 3 network device must learn the network layer address (IP address) of the destination host or device. Additionally, the host or network device must learn the physical address (MAC address) of the destination host or device because IP packets must be encapsulated into frames for transmission over a physical network. Therefore, mapping from IP addresses to MAC addresses is required. ARP can resolve IP addresses into MAC addresses. Each host or network device maintains an ARP table to store mapping between IP and MAC addresses. ARP entries are classified into static and dynamic ARP entries.