36
ARP Configuration
Wh n configuring ARP
e
, go to these sections for information you are interested in:
z
Introduction to ARP
z
Configuring ARP
z
Configuring Gratuitous ARP
Displaying and Debugging ARP
z
amples
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ARP Configuration Ex
to ARP
ARP
ice must know the data link layer address (MAC address, for example) of the
estination host or the next hop. To this end, the IP address must be resolved into the corresponding
data link layer address.
Introduction
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 dev
d
Unless otherwise stated, a data link layer address in this chapter refers to a 48-bit Ethernet MAC
ddress.
a
ARP
P
Message Format
AR messages are classified as ARP request messages and ARP reply messages.
Figure 36-1
trates the format of these two types of ARP messages.
illus
t the hardware address of the receiver field are set. The
hardware address of the receiver is what the sender requests for.
z
As for an ARP reply, all the fields are set.
z
As for an ARP request, all the fields excep
36-1