Compare GBN, SR, and TCP (no delayed ACK). Assume that the timeout values for al

Question

Compare GBN, SR, and TCP (no delayed ACK). Assume that the timeout values for all three protocols are sufficiently long such that 5 consecutive data segments and their corresponding ACKs can be received (if not lost in the channel) by the receiving host (B) and the sending host (A) respectively. Suppose host A sends 5 data segments to host B, and the second segment (sent from A) is lost. In the end, all 5 data segments have been correctly received by host B.

a. How many segments has host A sent in total and how many ACKs has host B sent in total? What are their sequence number? Answer this question for all three protocols.

b. If the timeout values for all three protocols are much longer than 5 RTT, then which protocol successfully delivers all five data segments in the shortest time interval?

Explanation / Answer

Answer :

a) Host a sends 9 segments in total. Firstly , sent segments 1 , 2 , 3 , 4 , 5 and later resent 2 , 3, 4 , 5. On the other hand B sends 4 ACKS with the sequence number 1 and 4 ACKS, these are with sequence number 2 , 3 , 4 , 5 .

SR ---- Here total 6 segments are sent with initially as 1 , 2 , 3 , 4 , 5 and then recent segment 2. Here the B sends 5 ACKS : - 4 ACKS with sequence number 1 , 3 , 4 , 5 and other with sequence number 2.

TCP ---- In TCP , 6 segments total.

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