Review this page: https://www.cloudshark.org/captures/d55a037d8f84

(Links to an external site.)Links to an external site. and answer the following questions. Provide annotated screen shots to support your answers where requested.

What is the IP address and TCP port number used by the client computer (source) that is transferring the file to gaia.cs.umass.edu? To answer this question, its probably easiest to select an HTTP message and explore the details of the TCP packet used to carry this HTTP message, using the details of the selected packet header window (white section of CloudShark). Provide a screen shot.

What is the IP address of gaia.cs.umass.edu? What port number is this server using to send and receive TCP segments for this connection? Provide a screen shot.

What is the sequence number (SEQ) of the TCP SYN segment that is used to initiate the TCP connection between the client computer and gaia.cs.umass.edu? What is it in the segment that identifies the segment as a SYN segment? Provide a screen shot. Note, this is not the packet number in the leftmost column of CloudShark. Look in the Info column for Seq=.

What is the sequence number of the SYNACK segment sent by gaia.cs.umass.edu to the client computer in reply to the SYN? What is the value of the ACKnowledgement number in the SYNACK segment? How did gaia.cs.umass.edu determine that value? What is it in the segment that identifies the segment as a SYNACK segment? Provide a screen shot that displays the SYN and ACK field values.

Now, locate the packet containing the HTTP GET command. Note that in order to find the packet, look for the GET command in the INFO column of the Cloudshark packet listing. What is the TCP Length? (Look for Len: in the Transmission Control Protocol headers in the center white section of CloudShark, not the Length Column in the green part). Now, find the ACK from the server back to the workstation (should be the next packet in the trace). What is the ACK number in the ACKnowledgement? Explain the relationship between this number and the TCP Length (above). Provide a screen shot or two showing these values.

Packet #12 in the trace starts the transfer of the upload of Alice.txt to the server. Look at the next several TCP Segments that go FROM THE CLIENT TO THE SERVER. Look into the details section of Cloudshark for each of these segments and identify the TCP Packet length of each of the next six (6) TCP segments that go from the client to the server. What are these lengths? Note, dont simply report the full Ethernet frame length that is what you see in packet top section of Cloudshark (in green). Instead go to the details section of Cloudshark (in white) and report the TCP Packet length. Provide a screen shot of one of these segments.

Look at the TCP Window size value in the ACKnowledgements coming from the server back to the workstation for the transfer of the file. (Hint: the key to answering this question is to look for 3 duplicate window size values, which signals/triggers the Slowstart protocol.) Fill in the table below for each ACK between packets 11 and 158. DO NOT provide a screenshot for this question.

Packet Number	Ack Number	Window Size
11
16
158

Note: make this table as long as needed to show all of the ACKs. At which packet number (see hint above) does TCPs Slowstart phase end and when does TCPs Collision Avoidance phase begin (see hint above)? In the last part of the lab, you will calculate the throughput of the upload of the file. Identify the FIRST transmitted packet that contains the upload of Alice In Wonderland text. This packet goes from the workstation to the server. Its one of those segments that is labeled [TCP segment of a reassembled PDU] in the info column. Look in the details panel (bottom, white section) of CloudShark for something that looks like:

0010 05 8c 6f 58 40 00 80 06 f6 6b 82 cb 97 58 80 77 ..oX@....k...X.w

0020 f5 0c ce 62 00 50 9a 9f dc ba 1c 94 ad aa 50 10 ...b.P........P.

0030 40 b0 9a 40 00 00 50 4f 53 54 20 2f 65 74 68 65 @..@..POST /ethe

0040 72 65 61 6c 2d 6c 61 62 73 2f 6c 61 62 33 2d 31 real-labs/lab3-1

0050 2d 72 65 70 6c 79 2e 68 74 6d 20 48 54 54 50 2f -reply.htm HTTP/

0060 31 2e 31 0d 0a 48 6f 73 74 3a 20 67 61 69 61 2e 1.1..Host: gaia.

0070 63 73 2e 75 6d 61 73 73 2e 65 64 75 0d 0a 55 73 cs.umass.edu..Us

0080 65 72 2d 41 67 65 6e 74 3a 20 4d 6f 7a 69 6c 6c er-Agent: Mozill

.

. There are some more packet details left out here that arent too helpful

.

02c0 20 20 20 20 20 20 20 20 20 20 41 4c 49 43 45 27 ALICE'

02d0 53 20 41 44 56 45 4e 54 55 52 45 53 20 49 4e 20 S ADVENTURES IN

02e0 57 4f 4e 44 45 52 4c 41 4e 44 0d 0a 0d 0a 20 20 WONDERLAND....

02f0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20

0300 20 20 20 20 20 20 20 20 4c 65 77 69 73 20 43 61 Lewis Ca

0310 72 72 6f 6c 6c 0d 0a 0d 0a 20 20 20 20 20 20 20 rroll....

a.What is the SEQ number of this FIRST segment? Provide a screen shot for 8a and b together. b.What time was this FIRST segment sent? Identify the LAST transmitted packet. Look for the HTTP packet that has POST /ethereal-labs/lab3-1-reply.htm HTTP/1.1 (text/plain) in the INFO column. c.What is the SEQ number of this LAST segment? Look in the Transmission Control Protocol headers for the Next Sequence number." What is this value? Provide a screen shot for 8c and d together. d.What time was this LAST segment sent?

Using the answers from a-d, above, calculate the amount of data sent and amount of time it took to send the data. Show your work. Consider that useful bandwidth calculations are often represented in bits/second or Megabits/second. If your values are in bytes, youll need to multiply by 8 to get bits. To get Megabits from bits, you should divide by 1,048,576 (since thats the number of bits in a Megabit). DO NOT provide a screen shot for this; just your calculations are sufficient.

Explain what would be wrong with doing this calculation using the values from packet #1 and packet #160 (the first and last packets in this capture file).