Homework Assignment 41 Due Friday Dec 7th 3 50PM EE122 Introduction to Communication Networks Fall 2007 Department of Electrical Engineering and Computer Sciences College of Engineering University of California Berkeley Vern Paxson Jorge Ortiz Lisa Fowler Daniel Killebrew Turn in as hardcopy to the drop box in 240 Cory 1 a Kurose Ross Chapter 2 p 186 i P21 ii P22 b Kurose Ross Chapter 6 pp 581 582 i P8 parts a b c and e not part d c Kurose Ross Chapter 7 pp 672 673 i P23 d Kurose Ross Chapter 8 p 751 i P9 2 Sizing Header Fields You are designing a reliable sliding window byte stream protocol similar to TCP It will be used for communication with a geosynchronous satellite network for which the bandwidth is 1 Gbps and the RTT is 275 ms Assume the maximum segment lifetime is 30 seconds a How many bits wide should you make the AdvertisedWindow and SequenceNum fields b If AdvertisedWindow is 16 bits what upper bound would that impose on the effective bandwidth c If it turns out that 0 5 of the packets sent over the path are lost what throughput would you expect a long running TCP connection to achieve Assume a value of AdvertisedWindow large enough to not impede performance 1 Version 1 Nov 20 1 3 QoS a Suppose the capacity C of a link is 18 Assume that 4 sources S1 S2 S3 and S4 are trying to send over the link at rates of r1 2 r2 4 r3 5 and r4 8 respectively What is the max min fairness allocation b For each of the following statements indicate whether it applies to Integrated Services IntServ Differentiated Services DiffServ and or Best Effort A given statement can apply to more than just one type of service i ii iii iv The service is provided end to end Among the three requires the most state in routers Is widely available in the Internet today Provides isolation and guarantees among aggregated flows but not individual connections 4 Queueing Theory Jorge wants to find the average number of people in his office hours which are from 1PM 2PM He observes the following three people and the times that they arrive and leave Alice 1 00 1 20PM Bob 1 10 1 45PM Eve 1 40 2PM Use Little s Law to compute the mean number of people in his office 5 Time Sequence Plots a For the packet trace recorded using tcpdump at http inst eecs berkeley edu 7Eee122 fa07 hw hw4 trace1 tcpdump construct a time sequence plot for the data packets and acknowledgments and use it to identify The approximate RTT The overall throughput The largest effective window size used The approximate maximum throughput obtained over two or more flights of packets Whether the connection is ever limited by the advertised window b Construct time sequence plots for the packet traces at http inst eecs berkeley edu 7Eee122 fa07 hw hw4 trace2 tcpdump and http inst eecs berkeley edu 7Eee122 fa07 hw hw4 trace3 tcpdump For these traces identify retransmitted packets and for each note whether it occurred due to Timeout or Fast Retransmission For the latter does the plot indicate that the sender also used Fast Recovery Include copies of your plots with your answers 2
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