3Com WX3000 ARP Configuration, Introduction to ARP, ARP Function, ARP Message Format

1 ARP Configuration

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The term switch used throughout this chapter refers to a switching device in a generic sense or the switching engine of the WX3000 series.

The sample output information in this manual was created on the WX3024. The output information on your device may vary.

Introduction to ARP

ARP Function

Address Resolution Protocol (ARP) is used to resolve an IP address into a data link layer address.

An IP address is the address of a host at the network layer. To send a network layer packet to a destination host, the device must know the data link layer address (MAC address, for example) of the destination host or the next hop. To this end, the IP address must be resolved into the corresponding data link layer address.

Unless otherwise stated, a data link layer address in this chapter refers to a 48-bit Ethernet MAC address.

ARP Message Format

ARP messages are classified as ARP request messages and ARP reply messages. Figure 1-1 illustrates the format of these two types of ARP messages.

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As for an ARP request, all the fields except the hardware address of the receiver field are set. The hardware address of the receiver is what the sender requests for.

As for an ARP reply, all the fields are set.

1-1