Chapter 1 Arp Configuration; Introduction To Arp; Necessity Of The Address Resolution; Arp Packet Structure - Huawei Quidway S3900 Series Operation Manual

Operation Manual – ARP
Quidway S3900 Series Ethernet Switches-Release 1510

Chapter 1 ARP Configuration

1.1 Introduction to ARP

Address resolution protocol (ARP) is used to map IP addresses to the corresponding
MAC addresses so that packets can be delivered to their destinations correctly.

1.1.1 Necessity of the Address Resolution

After a packet is forwarded to the destination network, MAC address is necessary for
the packet to reach the very device. So the destination IP address carried in a packet
need to be translated into the corresponding MAC address.

1.1.2 ARP Packet Structure

ARP packets are classified as ARP request packets and ARP reply packets. Figure
1-1 illustrates the structure of these two types of ARP packets.
As for an ARP request packet, all the fields except the hardware address of the
receiver field are set. The hardware address of the receiver is what the sender
request for.
As for an ARP reply packets, all the fields are set.
Length of the hardware address
Figure 1-1 Structure of an ARP request/reply packet
Table 1-1 describes the fields of an ARP packet.
Table 1-1 Description on the fields of an ARP packet
Hardware Type
Hardware type (16 bits)
Protocol type (16 bits)
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
Field
Huawei Technologies Proprietary
1-1
Chapter 1 ARP Configuration
Description
Identifies the type of the hardware interface.
Refer to Table 1-2 for the information about
the field values.