Wireshark Lab

1.) 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? Anser! The IP address and TCP port number of my computer is 1".".".1#$ and port number is %"%&1 as shon in the belo figure 1.

'igure 1! IP address and Port number of source computer.

$.) What is the IP address of gaia.cs.umass.edu? n hat port number is it sending and receiing TCP segments for this connection? Anser! The IP address of gaia.cs.umass.edu is 1$*.11#.$+%.1$ and the port number it is sending TCP segments is *" as shon in the belo figure $.

'igure $! IP address and Port number of gia.cs.umass.edu

,.) What is the IP address and TCP port number used by your client computer (source) to transfer  the file to gaia.cs.umass.edu? Anser! The IP address and TCP port number of my computer is 1".".".1#$ and %"%&1. +.) What is the se-uence number of the TCP /0 segment that is used to initiate the TCP connection beteen the client computer and gaia.cs.umass.edu? What is it in the segment that identifies the segment as a /0 segment? Anser! The se-uence number of the TCP /0 segment that is used to initiate the TCP connection beteen the client computer and gaia.cs.umass.edu is " / segment is 1 as shon in the belo figure ,.

'igure ,! TCP /0 segment beteen source and destination

%.) What is the se-uence number of the /0AC2 segment sent by gaia.cs.umass.edu to the client computer in reply to the /0? What is the alue of the Ac3noledgement field in the /0AC2 segment? 4o did gaia.cs.umass.edu determine that a lue? What is it in the segment that identifies the segment as a /0AC2 segment? Answer: e-uence

number of the /0AC2 segment sent by gaia.cs.umass.edu to the client

computer in reply to the /0 is " and ac3noledgement is 1 as shon in the belo figure +.

'igure +! e-uence number of /0AC2

5.) What is the se-uence number of the TCP segment containing the 4TTP PT command?  0ote that in order to find the PT command you6ll need to dig into the pac3et content field at the bottom of the Wireshar3 indo loo3ing for a segment ith a 7PT8 ithin its 9ATA field. Answer:

4TTP PT command is 'rame + as shon in the belo figure %.

'igure %! 4TTP PT command &.) Consider the TCP segment containing the 4TTP PT as the first segment in the TCP connection. What are the se-uence numbers of the first si: segments in the TCP connection (including the segment containing the 4TTP PT)? At hat time as each segment sent? When as the AC2 for each segment receied? ;ien the difference beteen  hen each TCP segment as sent and hen its ac3noledgement as receied hat is the
4TTP PT segment is 0o. +1$+,,+,5 ++1 +++ AC2 segment is 0o. +"* +11 +1, +,+ +,% and +,#

egment 1 e-uence 0umber is 1 egment $ e-uence 0umber is 1+"51 egment , e-uence 0umber is 1&%$1 egment + e-uence 0umber is $"++1 egment % e-uence 0umber is $,,51 egment 5 e-uence 0umber is $5$*1 Calculated =stimated
egment1 egment$ egment, egment+ egment% egment5

ent Time *.%5$*"" *.5"&,$% *.51&&1$ *.5,&"1& *.5,&$5# *.5+$55+



=stimated ".*&%=stimated "."1$$11 =stimated ".*&%"."1$$11@".1$%".""#$"% > "."11* =stimated ".*&%"."11*@".1$%"."1#"&+ > "."1$&" =stimated ".*&%"."1$&@".1$%"."""115 > "."111$& =stimated ".*&%"."111$&@".1$%"."""""* > "."""""1 =stimated ".*&%"."""""1@".1$%"."""1"1 > ".""""1,%

*.) What is the length of each of the first si: TCP segments? Answer:

ength of first TCP segment is &&5 bytes and ength of the other TCP segments (%

TCP segments) is 1+$5 bytes.

#.) What is the minimum amount of aailable buffer space adertised at the receied for the entire trace? 9oes the lac3 of receier buffer space eer throttle the sender? Answer:

minimum amount of aailable buffer space adertised at the receied for the entire

trace is $%5 bytes 1".) Are there any retransmitted segments in the trace file? What did you chec3 for (in the trace) in order to anser this -uestion? Answer:

/es there is a retransmission in the trace file e can chec3 it by obsering from the

se-uence number.

11.) 4o much data does the receier typically ac3noledge in an AC2? Can you identify cases here the receier is AC2ing eery other receied segment Answer:

The receier has already ac3noledged the data it receied from its preious

ac3noledgement.

1$.) What is the throughput (bytes transferred per unit time) for the TCP connection? =:plain ho you calculated this alue. Answer: Aerage

throughput of a connection > (".&%W)B
Windo sie of first segment! 5%%,5 +"$%$$,.1%#++5+"1 >+"$ 2bytesBsec

1,.) Dse the TimeEe-uenceE;raph (teens) plotting tool to ie the se-uence number ersus time plot of segments being sent from the client to the gaia.cs.umass.edu serer. Can you identify here TCP6s slo start phase begins and ends and here congestion aoidance ta3es oer? Comment on ays in hich the measured data differs from the idealied behaior of TCP that e6e studied in the te:t. Answer:

The folloing figure shos the TimeEe-uenceE;raph (teens) plotting tool hen

TCP hae connected beteen ender and
1+.) Anser each of to -uestions aboe for the trace that you hae gathered hen you transferred a file from your computer to gaia.cs.umass.edu Answer: When

e hae a lot of traffic on netor3 TCP sender uses AIF9 algorithm for the

reduction of indo sie.