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QUESTION 5 [TOTAL MARKS: 25] Q5a [13 Marks] Suppose a packet stream travels from Dublin to New York (approximately 5000 km). The propagation speed is 2.0 x 10^8 m/sec. Suppose further each packet is 10,000 bytes and is transmitted at the sender at a rate of 100 Mbps = 10^8 bits per second. You may assume transmission and processing delays are small relative to the propagation delay, that there are no queuing delays, and that the ACK size is small (so transmission time is negligible). i) How many packets may be transmitted before the first is acknowledged? (4 marks) ii) Suppose that we use a window-based Transport layer protocol. What window size would be required to achieve a maximum efficiency of 0.70? (5 marks) iii) For the above scenario, in 100 words or less, discuss the pros and cons of using Go-Back-N vs Selective Repeat protocols to provide reliable data transport. (4 marks) [12 Marks] Q5b) Suppose TCP Reno is being used as a transport layer protocol. For twenty transmission rounds, indicate the size of the congestion window and threshold value assuming a triple duplicate ACK occurs just after round 11 and a timeout occurs just after round 14. Assume the initial threshold value is 64. [End of Question 5]

          QUESTION 5
[TOTAL MARKS: 25]

Q5a
[13 Marks]

Suppose a packet stream travels from Dublin to New York (approximately 5000 km). The propagation speed is 2.0 x 10^8 m/sec. Suppose further each packet is 10,000 bytes and is transmitted at the sender at a rate of 100 Mbps = 10^8 bits per second. You may assume transmission and processing delays are small relative to the propagation delay, that there are no queuing delays, and that the ACK size is small (so transmission time is negligible).

i) How many packets may be transmitted before the first is acknowledged? (4 marks)

ii) Suppose that we use a window-based Transport layer protocol. What window size would be required to achieve a maximum efficiency of 0.70? (5 marks)

iii) For the above scenario, in 100 words or less, discuss the pros and cons of using Go-Back-N vs Selective Repeat protocols to provide reliable data transport. (4 marks)

[12 Marks]

Q5b) Suppose TCP Reno is being used as a transport layer protocol. For twenty transmission rounds, indicate the size of the congestion window and threshold value assuming a triple duplicate ACK occurs just after round 11 and a timeout occurs just after round 14. Assume the initial threshold value is 64.

[End of Question 5]

question 5 total marks 25 q5a 13 marks suppose a packet stream travels from dublin to new york approximately 5000 km the propagation speed is 20 x 108 msec suppose further each packet is 100 55709

Added by Ryan F.

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