two host A and B are communicating with each other using TCP. Assume that the sequence number field starts at 0 and the receiver employs cummulative ACK. A has successfully send 465 bytes of data which were also acked by B. Suppose A were now to send 3 segment of size 110, 40, 60 size. what sequence number will the third segment carry ??
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Hi MdJadu, and welcome to Stack Overflow. Sorry to say this, but your question isn't strictly about programming so it doesn't really belong on this site. Another site in the StackExchange network might be a better fit; however, a question for any site on StackExchange needs to show that you've made some attempt at solving the problem yourself before asking for help.
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1 Answers
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This is very simple to work out, and it sounds a lot like a homework problem. I usually won't answer these, but...
Remember that the initial SYN consumes 1 byte in the connection. This means that the initial SYN with sequence number zero is ACKed as 1.
We now transfer 465 bytes. This means that the last sequence number ACKed will be 466, and 466 will now appear as the sequence number from A to B.
We now send 110 bytes. The sequence number in the packet will be 466 with a data payload of 110. The ACK will be for 576.
Following this, 40 more bytes are sent. This will have a sequence number of 576 in the packet with 40 bytes of payload and the ACK will be for 616.
That brings us to the last segment. The sequence number in the segment should be 616, as long as I've done the maths correctly in my head, and this is the sequence number in the packet that you are asking about. The ACK for that will be for 676.
