P34. Compare GBN, SR, and TCP (no delayed ack). Assume that the timeout values f

Question

P34. 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 (Host B) and the sending host (Host A)
respectively.Suppose host A sends 5 data segments to host B, and the 2nd 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 numbers? 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 shortest
time interval?

Explanation / Answer

a)

For Go-Back-N:

   Host A sent total number of segments is 9.The initial segment numbers are 1,2,3,4,5 and re-sent the segemnts 2,3,4 and 5 because 2nd segment was lost.

 Host B sent the number of ACKs are 8.Host B sent ACKs 1 by four times because 2nd segment was lost and sent 4ACKs with sequence numbers 2,3,4 and 5

selective repeat:

  Host A sent total number of segments is 6.The initial segment numbers are 1,2,3,4,5 and re-sent the segemnts 2 because 2nd segment was lost.

Host B sent the number of ACKs are 5.Host B sent four ACKs with sequence numbers 1,3,4,5 and re-sent ACK2 with sequence number 2 because 2nd segment was lost.

TCP :

 Host A sent total number of segments is 6.The initial segment numbers are 1,2,3,4,5 and re-sent the segemnts 2 because 2nd segment was lost.

Host B sent the number of ACKs are 5.Host B sent four ACKs with sequence number 2 and There is one ACK with sequence number 6.TCP always send an ACK with expected sequence number

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

 

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