Host A and Host B are communicating over a TCP connection, and Host B has alread
ID: 3655936 • Letter: H
Question
Host A and Host B are communicating over a TCP connection, and Host B has already received from A all bytes up through byte 700. Suppose Host A then sends two segments to Host B back-to-back with first and second segments containing 80 and 100 bytes of data, respectively. In the first segment, the source port number is 7777, and the destination port number is 80.
a. What is the sequence number in the first segment sent from Host A to B?
b. In the second segment sent from Host A to B, what are the sequence number, source port number, and destination port number?
c. If the first segment arrives before the second segment, in the acknowledgement of the first arriving segment, what is the acknowledgement number, the source port number and the destination port number?
Explanation / Answer
Sequence number (in ACK packet) is a byte number the peer expects to receive next or the byte number from that the peer starts transmisson (in data packet). > a) In the second segment sent from Host A to Host B, what are the sequence number, source port number and destination port number? Sequence number 289 Source port 503 Destination port 80 b) If the first segment arrives before the second segment, in the acknowledgement of the first arriving segment what are the acknowledgement sequence number, the source port number, and the destination port number? ACK sequence number = 289 Source number 80 (reversed) Destination number 503 c) If the second segment arrives before the first segment, in the acknowledgement of the first arriving segment what is the acknowledgement sequence number? Exactly the same as b) because "TCP primarily uses a cumulative acknowledgment scheme, where the receiver sends an acknowledgment signifying that the receiver has received all data preceding the acknowledged sequence number." ACK sequence number = 289 Source number 80 Destination number 503 Read more: Hosts A and B are communicating over a TCP connection, and - JustAnswer http://www.justanswer.com/computer-programming/3ejg5-hosts-communicating-tcp-connection.html#ixzz298lVZIUE
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