Lab 7
Ethernet and ARP
1. Capturing and analyzing Ethernet frames
STEPS
鈥?nbsp;First, make sure your browser鈥檚 cache is empty. (To do this under Netscape 7.0,
select Edit->Preferences->Advanced->Cache and clear the memory and disk cache.
For Internet Explorer, select Tools->Internet Options->Delete Files. For Firefox select
Tools->Clear Private Data.
鈥?nbsp;Start up the Wireshark packet sniffer
鈥?nbsp;Enter the following URL into your browser http://gaia.cs.umass.edu/wireshark-
labs/HTTP-ethereal-lab-file3.html Your browser should display the rather lengthy US
Bill of Rights.
鈥?nbsp;Stop Wireshark packet capture. First, find the packet numbers (the leftmost column
in the upper Wireshark window) of the HTTP GET message that was sent from your
computer to gaia.cs.umass.edu, as well as the beginning of the HTTP response
message sent to your computer by gaia.cs.umass.edu. You should see a screen that
looks something like this (where packet 4 in the screen shot below contains the HTTP
GET message)
鈥ince this lab is about Ethernet and ARP, we鈥檙e not interested in IP or higherlayer
protocols. So let鈥檚 change Wireshark鈥檚 鈥渓isting of captured packets鈥?nbsp;window so that it
shows information only about protocols below IP. To have Wireshark do this, select
Analyze->Enabled Protocols. Then uncheck the IP box and select OK.
QUESTIONS
1.
What is the 48-bit Ethernet address of your computer?
The 48-bit Ethernet address of your computer is 3c : 97 : 0e : ff : 69 : 02
2.
What is the 48-bit destination address in the Ethernet frame? Is this the Ethernet
address of gaia.cs.umass.edu? (Hint: the answer is no). What device has this as its
Ethernet address? [Note: this is an important question, and one that students