11ARP configurationARP overviewARP functionARP is used to resolve an IP address into a physical address, such as an Ethernet MAC address.In an Ethernet LAN, when a device sends data to another device, it uses ARP to translate the destinationIP address to the corresponding MAC address.ARP message formatARP messages include ARP requests and ARP replies. Figure 1 shows the ARP message format.Figure 1 ARP message formatThe following explains the fields in Figure 1.• Hardware type: This field specifies the hardware address type. The value “1” represents Ethernet.• Protocol type: This field specifies the type of the protocol address to be mapped. The hexadecimalvalue “0x0800” represents IP.• Hardware address length and protocol address length: They respectively specify the length of ahardware address and a protocol address, in bytes. For an Ethernet address, the value of thehardware address length field is "6”. For an IP(v4) address, the value of the protocol address lengthfield is “4”.• OP: Operation code. This field specifies the type of ARP message. The value “1” represents an ARPrequest and “2” represents an ARP reply.• Sender hardware address: This field specifies the hardware address of the device sending themessage.• Sender protocol address: This field specifies the protocol address of the device sending the message.• Target hardware address: This field specifies the hardware address of the device the message isbeing sent to.
