Question

Hosts A and B are communicating over a TCP connection, and Host B has already received from A all bytes up through byte 126. Suppose Host A then sends two segments to Host B back-to-back. The first and second segments contain 50 and 100 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 acknowledgement whenever it receives a segment from Host A.
1.In the second segment sent from A to B, what are the sequence number, source port number and destination port number?

2.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 destination port number?

3.If the second segment arrives before the first segment, in the acknowledgment of the first arriving segment, what is the acknowledgment number?

4.Suppose the two segments sent by A arrive in order at B. The first acknowledgment is lost and the second acknowledgment arrives after the first timeout interval. Draw a timing diagram, showing these segments and all other segments and acknowledgments sent. (Assume there is no additional packet loss).

Answer 1

Answer:

1) sequence number=207 ,Source port number = 302, Destination port number= 80

2) Acknowledgement number= 207, Source port number = 80                   Destination port number= 302

3) Acknowledgement number=127

4) View the attached file for the Timing diagram

Explanation:

1) The sequence number is 127 + 80 = 207, the source port number is 302, and the destination port number is 80.

2) The acknowledgement number is 207, source port number is 80 and the destination port number is 302 if the first segment arrives before the second segment, in the acknowledgment of the first arriving segment.

3) The acknowledgement number is 127, indicating that the receiver is still waiting for bytes 127 and onward.

4) View attached file.