QUESTION 4 – TCP and GBN - Host A and B are communicating over a TCP connection, and Host B has already received from A

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Question 4 Tcp And Gbn Host A And B Are Communicating Over A Tcp Connection And Host B Has Already Received From A 1 (218.57 KiB) Viewed 68 times

QUESTION 4 – TCP and GBN - Host A and B are communicating over a TCP connection, and Host B has already received from A all bytes up through and including byte 126 and host A has already received from B all the corresponding acknowledgements. Suppose Host A then sends two segments to Host B back-to-back. The first and second segments contain 80 and 40 bytes of data, respectively. In the first segment, the sequence number is 127, the source port number is 302, and the destination port number is 80. Host B sends an acknowledgment whenever it receives a segment from Host A. a) In the second segment sent from Host A to B, what are the sequence number, source port number, and destination port number? b) If the first segment arrives before the second segment, in the acknowledgment of the first arriving segment, what is the acknowledgment number, the source port number, and the destination port number? c) If the second segment arrives before the first segment, in the acknowledgment of the first arriving segment, what is the acknowledgment number? d) Now suppose that that there are five more segments available to be sent immediately after the two segments discussed already, and each of these five segments has size of 100bytes. Consider the scenario where the TCP window size is cwnd = 5 segments, and the first segment (of size 80 bytes) is lost and all other segments and acknowledgments are sent successfully. Assume the timeout value is equal to two times the Round- Trip-Time (RTT) and ignore any changes in the window size due to congestion control or fast recovery. You may assume ‘TCP Reno’ is the version of TCP being used. Draw a timing diagram to describe how all segments arrive at B, including sequence and ACK numbers, and buffering.