Submission Instructions Please submit your HW solutions by EMAIL to TA at bpetit@cc.gatech.edu. Make sure to include [CS3251] in subject line.:w

Late Policy: You have a total of 3-days for a late budget which you may use for any assignment in a minimum of day increments.

• Question 1

  Two routers (A and B) are connected over a 100Mbps Ethernet cable. The distance between the interfaces is 10 Km.

  Router A starts transmitting the first bit of a 512 byte packet at time 0 sec.

  Calculate when the last bit of the packet is received at Router B.

  Give your answer in as much precision as you can.

  Assume that signal propagation on the cable is 0.6c (that is 0.6 the speed of light). Also assume that the Ethernet is not shared.

• Questions 2 and 3 All questions from the Kurose and Ross text (3rd eddition)
  • Chapter 5: Question 12 (p496)

  • Chapter 5: Question 15 (p497)
• Question 4:

  This problem should be done on a Unix system connected somewhere on the Georgia Tech network. If you do not have a strong familiarity with the Unix (Solaris or Linux) operating system, this is a good time to start. You can use acme or one of the CoC cluster systems. You will be doing your later programming assignments using this platform.

  1. Read about the traceroute utility that allows one to trace the sequence of routers between two hosts on the Internet. A relatively high level description can be found on the web site for the Kurose and Ross textbook, which you will only be able to access if you purchased the book. A somewhat more technical description can be found by using the Unix manual pages (see man traceroute).
     1. Using your favorite browser, go to the web site www.traceroute.org. This site lists a collection of servers around the world that allow you to do traceroute from their systems.

     2. Select two different countries you would like to visit today. For each country, choose a site and run a traceroute back to your computer here at Georgia Tech. Do some experimenting and find two sites that give interesting results.

     3. Next, using the traceroute command, do a traceroute from Georgia Tech back to the remote systems you chose.

     4. Repeat the traceroute tests on two different days. You will have a total of 8 tests: 2 target sites, 2 directions per site, and tests on 2 different days.

     5. Save the output from these tests to turn in with your assignment. Answer the following questions.

        • Which Internet Service Providers can you identify? Which cities or countries?

        • Which hops experience the greatest delay? What might be the reasons for this?

        • What did you discover about the routes between your remote hosts and the host at Georgia Tech? Are they the same in both directions? Why or why not?

     6. Explain why the times reported by traceroute can sometimes decrease as you go from hop i to hop i+1.