GS2210 Series User’s Guide
401
C
H A P T E R
4 9
ARP Table
49.1 Overview
This chapt er int r oduces ARP Table.
Addr ess Resolut ion Pr ot ocol ( ARP) is a pr ot ocol for m apping an I nt er net Pr ot ocol addr ess ( I P
addr ess) t o a physical m achine addr ess, also know n as a Media Access Cont r ol or MAC addr ess, on
t he local area net w ork.
An I P ( ver sion 4) address is 32 bit s long. I n an Et hernet LAN, MAC addr esses are 48 bit s long. The
ARP Table m aint ains an associat ion bet w een each MAC addr ess and it s cor r esponding I P addr ess.
49.1.1 What You Can Do
Use t he ARP Ta ble scr een (
) t o view I P- t o- MAC addr ess m apping( s) .
49.1.2 What You Need to Know
When an incom ing packet dest ined for a host device on a local ar ea net w or k ar r ives at t he Sw it ch,
t he Swit ch's ARP pr ogram looks in t he ARP Table and if it finds t he addr ess, it sends it t o t he device.
I f no ent r y is found for t he I P addr ess, ARP br oadcast s t he r equest t o all t he devices on t he LAN.
The Swit ch fills in it s ow n MAC and I P addr ess in t he sender addr ess fields, and put s t he know n I P
addr ess of t he t ar get in t he t ar get I P addr ess field. I n addit ion, t he Swit ch put s all ones in t he
t ar get MAC field ( FF.FF.FF.FF.FF.FF is t he Et her net br oadcast addr ess) . The r eplying device ( w hich is
eit her t he I P addr ess of t he device being sought or t he r out er t hat know s t he way) r eplaces t he
br oadcast addr ess w it h t he t ar get 's MAC addr ess, swaps t he sender and t ar get pair s, and unicast s
t he answ er dir ect ly back t o t he request ing m achine. ARP updat es t he ARP Table for fut ur e r efer ence
and t hen sends t he packet t o t he MAC addr ess t hat r eplied.
49.2 Viewing the ARP Table
Use t he ARP t able t o view I P- t o- MAC address m apping( s) and r em ove specific dynam ic ARP ent r ies.
Click M a n a ge m e n t > ARP Ta ble in t he navigat ion panel t o open t he follow ing scr een.
