Figure 36-1
ARP message format
Hardware type (16 bits)
Protocol type (16 bits)
Length of hardware address Length of protocol address
Operator (16 bits)
Hardware address of the sender
IP address of the sender
Hardware address of the receiver
IP address of the receiver
Hardware type (16 bits)
Hardware type (16 bits)
Protocol type (16 bits)
Length of hardware address Length of protocol address
Operator (16 bits)
Hardware address of the sender
IP address of the sender
Hardware address of the receiver
IP address of the receiver
Table 36-1
describes the fields of an ARP packet.
Table 36-1
Description on the fields of an ARP packet
Field
Description
Hardware Type
Type of the hardware interface. Refer to
Table 36-2
for
the information about the field values.
Protocol type
Type of protocol address to be mapped. 0x0800
indicates an IP address.
Length of hardware address
Hardware address length (in bytes)
Length of protocol address
Protocol address length (in bytes)
Operator
Indicates the type of a data packets, which can be:
1: ARP request packets
2: ARP reply packets
3: RARP request packets
4: RARP reply packets
Hardware address of the sender
Hardware address of the sender
IP address of the sender
IP address of the sender
Hardware address of the receiver
For an ARP request packet, this field is null.
For an ARP reply packet, this field carries the hardware
address of the receiver.
IP address of the receiver
IP address of the receiver
Table 36-2
Description on the values of the hardware type field
Value
Description
1 Ethernet
2 Experimental
Ethernet
3 X.25
4
Proteon ProNET (Token Ring)
36-2