Network Technologies (TCP/IP suite) by 7K12OTua

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									Network Technologies (TCP/IP suite)
Problem Set #2: Due on Thursday 22nd May 2008.

Your solution should be handed in person to the instructor.

Pay close attention to units. A byte of storage is 8-bits, and 1-kilobit of storage is 1024
bits. By convention, the rules are different between storage and data rate: 1kb/s is 1,000
bits per second.
Show your reasoning clearly and if required, you are allowed to make reasonable
assumptions. If your reasoning is correct, but your final answer is wrong, you will receive
most of the credit. If you just show the answer without reasoning, and your answer is
wrong, you may receive no points at all. Hand in your solution on separate paper, and
remember it’s better to submit a wrong/incomplete solution rather than a copied
one without references.

1. (9 points). A FIFO queue has the following cumulative arrival process: At t - 20.
The outgoing link operates at 10 bits/second. Each time the queue goes empty, the
outgoing link goes idle until there are 100 bits in the queue, and starts operating again at
10 bits/second.
Find the time-average queue occupancy X and the average delay d of a bit through the
queue.

2. (1+2+2+2+4 points). Find out answers to the following questions. Make sure you
copy-paste the outputs or screenshots of the program you use to find out the answer.

   a) What countries do you think a packet goes through on its way to
      www.yahoo.com?
   b) Which organization owns the IP address 74.125.96.18?
   c) What is the Ethernet (hardware) address of your network interface and that of the
      network interface one hop away from your machine?
   d) Estimate the distance between Islamabad/Rawalpindi and Karachi by using the
      RTT for a packet sent from Islamabad/Rawalpindi to Karachi, and assuming there
      is no transmission delay and no queuing delay. Is it an accurate measure? Make
      sure you describe how you are able to find a host/router in Karachi (with relative
      certainty).
   e) In your sr (router) assignment, find the Ethernet address of your eth0 interface, as
      well as the Ethernet address of the router interface just before your own router.

3. (5+5 points) Using both Dijkstra’s algorithm and the Bellman-Ford algorithm, find the
shortest-path spanning-tree for routing packets to router R8 from every other router in the
following diagram. Clearly show each step for each algorithm like we did in class.

								
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