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374 Lab 5.pdf

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Emma Bryce
ECE 374
26 Apr. 2017

Lab 5
1. Ethernet

Fig. 1
1. What is the 48-bit Ethernet address of your computer? 78:31:c1:c7:5d:7e (Fig. 1)
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?
Destination address of Ethernet frame, 44:f4:77:2b:28:f0, is not the Ethernet address of
gaia.cs.umass.edu. The Ethernet frame just encapsulates the datagram for the immediate link,
so this Ethernet address belongs to the initial WiFi access point that the link is connecting to.
(Fig. 1)
3. Give the hexadecimal value for the two-byte Frame type field. What do the bit(s) whose
value is 1 mean within the flag field? 0x0800 (seen readily in wireshark)
4. How many bytes from the very start of the Ethernet frame does the ASCII “G” in “GET”
appear in the Ethernet frame?
66 bytes: After 14 bytes of Ethernet header, 20 bytes of IP header, and 32 bytes of TCP header
(Fig 1.)
Next, answer the following questions, based on the contents of the Ethernet frame containing
the first byte of the HTTP response message.
5. What is the value of the Ethernet source address? Is this the address of your
computer, or of gaia.cs.umass.edu (Hint: the answer is no). What device has this as its
Ethernet address? 44:f4:77:2b:28:f0 is the Ethernet source address of this frame, which is not
the address to of my computer or gaia.cs.umass.edu. It is again the initial WiFi access point.