Netis ST3326(ST-3302) [79/118] Introduction to arp

Netis ST3326(ST-3302) [79/118] Introduction to arp
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Figure 8-5-5
Port Type & List: Choose the port you want to set.
Port Option 82 Policy:There 3 modes of op 82 policy,Drop,Replace and Keep.
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.
ARP Message Format
ARP messages are classified as ARP request messages and ARP reply messages.
illustrates the format of these two types of ARP messages.
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.
ARP Table
In an Ethernet, the MAC addresses of two hosts must be available for the two hosts to
communicate with each other. Each host in an Ethernet maintains an ARP table, where the latest
used IP address-to-MAC address mapping entries are stored. The switches provide the show arp
command to display the information about ARP mapping entries.

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