quiz1key - Quiz 1 Key CNT 5106C (10 pts) 27 January 2011 1....

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Quiz 1 Key CNT 5106C (10 pts) 27 January 2011 1. (3) Compare the total time it takes to send a 5 million byte data file over a path with five hops when the data rate of each link is 1 Mbps and the propagation delay per link is 10 ms. for each of the following methods. Assume no errors. Show your work. a) Circuit switching with setup time S = 1 sec. b) Message switching with header H = 60 bytes c) Packet switching with header H = 60 bytes, packet size = 1000 bytes KEY: Data transmission time is 5,000,000 x 8 (bits)/1,000,000 (bps) = 40 seconds. Propagation delay is 5 hops x 10 ms/hop = 50 ms = 0.050 seconds. a) (1) C-S: setup = 1 sec., then transmission time 40 s., then propagation delay to deliver last bit 0.05 s., TOTAL = 41.05 sec. b) (1) M-S: one header sent with message – 60x8 bits/1,000,000 bps = 0.000480 sec. to transmit. Each hop takes 40.000480 s transmission time plus 0.01 s propagation delay, and whole message must arrive before transmission can start on next hop. TOTAL = 5x40.01048 =
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quiz1key - Quiz 1 Key CNT 5106C (10 pts) 27 January 2011 1....

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