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

Question

Compare GBN, SR and TCP (no delayed ACK). Assume that the timeout values for all three protocols are sufficiently long such that 10 consecutive data segments and the corresponding ACKs can be received (if not lost in the channel) by the receiving host (Host B) and the sending host (Host A) respectively. Suppose Host A sends 10 data segments to Host B, and the fifth segment (sent from A) is lost. In the end, all 10 data segments have been correctly received by Host B.

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

If the timeout values for all three protocols are much longer than 10 RTT, then which protocol successfully delivers all 10 data segments in the shortest time interval?

Explanation / Answer

Go Back N:

A sends 16 segments. They are initially sent segments 1,2,3,4,5,6,7,8,9,10 and later resent 5,6,7,8,9,10. B sends 15 ACKS .They are 9 ACKS with sequence number 1,2,3,4,6,7,8,9,10 and and 6 ACKS with sequence number 5,6,7,8,9,10

selective repeat :

A sends 11 segments.They are initially sent segments 1,2,3,4,5,6,7,8,9,10 and later resent segment 5. B sends 10 ACKS.They are 9 ACKS with sequence number 1,2,3,4,6,7,8,9,10 ans there is one ACK qith sequence number 5.

TCP:

A sends 11 segments. They are initially sent segments 1,2,3,4,5,6,7,8,9,10 and later resent segment 5. B sends 10 ACKS. They are 9 ACKs with sequence number 5. there is one ACK with sequence number 11.

b) TCP. This is because TCP uses fast retransmit without waiting until time out.

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