tutorial1 - n of them need to use the telephone at the same...

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EE3015 Tutorial 1 (Circuit Switching vs. Packet Switching; Throughput and Delay) Review Questions: y What are the three major components of the Internet? y What is the difference between circuit switching and packet switching? y What is multiplexing? List some common multiplexing techniques. Problems: 1. Consider an application that transmits data at a steady rate. Also, when such an application starts, it will continue running for a relatively long period of time. Would a packet-switched network or a circuit-switched network be more appropriate for this application? Why? 2. Suppose there are four employees working in your company. Each employee uses the telephone 20% of the time. a) If each employee is given a dedicated telephone line, how many telephone lines are needed? b) Suppose you want to minimize the cost by reducing the telephone lines. i. Find the probability that exactly
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Unformatted text preview: n of them need to use the telephone at the same time. ii. Suppose you want to minimize the number of telephone lines installed. How many telephone lines should you provide for them if you want the probability that they need to wait for the telephone be less than 0.03? c) What kind of multiplexing technique is used in part (b)? 3. Suppose Host A wants to send a large file to Host B. The path from Host A to Host B has three links, of rates R 1 = 500 kbps, R 2 = 2 Mbps, and R 3 = 1 Mbps. a) Assuming no other traffic in the network, what is the throughput (in bits per second) for the file transfer? b) Suppose the file is 4 Mbytes. How long will it take to transfer the file to Host B? (Note: 1 Mbyte = 1024 Kbytes = 1024 × 1024 bytes. In this question, ignore propagation delay.) c) Repeat (a) and (b), but now with R 2 reduces to 100 kbps....
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This note was uploaded on 05/01/2011 for the course ELECTRICAL EE3015 taught by Professor Albertsun during the Spring '11 term at City University of Hong Kong.

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