Lectures notes for 2010 - KTH

Address Resolution Cache
Since you have just looked up the address, save (cache) it for reuse:
• to limit ARP traffic
• works because of correlations in use of addresses
You can examine the arp cache:
arp -a
machine-name (x.x.x.x) at xx:xx:xx:xx:xx:xx
…
arp -an
(x.x.x.x) at xx:xx:xx:xx:xx:xx
…
Note that the later form (with the “n” option) does not lookup the hostname, this
is very useful when you don’t yet have a name resolution service working!
ARP Refinements
Since the sender’s Internet-to-Physical address binding is in every ARP broadcast;
(all) receivers update their caches before processing an ARP packet
Maguire Address Resolution Cache 2: 22 of 52
maguire@kth.se 2010.03.21 Internetworking/Internetteknik