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quiz3key - Transmit time =(500 bytes(8 B/bit/10 Mbps = 4000...

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Quiz 3 CNT 5106C 22 February 2011 Instructions: Write your last name, then first initial in upper righthand corner of answer sheet, and write “Quiz 3” centered at top. Answer all questions. 1. Consider a path with round trip time 30 ms. and data rate 10 Mbps. Suppose you send segments of length 500 bytes to a receiver, using 1-bit ARQ. What is the effective data rate of the connection? 2. How many bits of sequence number are required to achieve the maximum data rate using GBN-ARQ? Key 1. Cycle time = RTT + transmit time
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Unformatted text preview: Transmit time = (500 bytes)(8 B/bit)/10 Mbps = 4000 bits/10 Mbps = 400 usec Cycle time = 30,000 usec + 400 usec = 30,400 usec. Only one segment can be sent per cycle time, So data rate is 4000 bits/30,400 usec < 132 kbps 2. GBN ARQ requires a send window no greater than 2 n-1, where n is the number of bits in the sequence numbers, and a receive window of size 1. The number of segments needed to fill the pipeline is then Cycle time/transmit time 30,400/400 = 76 So n >=ceil( log 2 (76+1)) = 7 bits....
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