H3C Technologies H3C SecPath F1000-E - Manual (Page 495)

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ARP Configuration
ARP Overview
ARP Function
The Address Resolution Protocol (ARP) is used to resolve an IP address into a physical address (Ethernet
MAC address, for example).
In an Ethernet LAN, when a device sends data to another device, it uses ARP to translate the IP address
of that device to the corresponding MAC address.
ARP Message Format
ARP messages are classified into ARP requests and ARP replies. Figure 1 shows the format of the ARP
request/reply.
Figure 1 ARP message format
The following describes 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 hexadecimal
value “0x0800” represents IP.
• Hardware address length and protocol address length: They respectively specify the length of a
hardware address and a protocol address, in bytes. For an Ethernet address, the value of the
hardware address length field is "6”. For an IP(v4) address, the value of the protocol address
length field is “4”.
• OP: Operation code. This field specifies the type of the ARP message. The value “1” represents an
ARP request and “2” represents an ARP reply.
• Sender hardware address: This field specifies the hardware address of the device sending the
message.
• 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 is
being sent to.