If a data stream using TCP has filled the output buffer with 3600 bytes and needs to be transferred through an installed connection to a server. If the congestion window is 1400 bytes, the window header field is 1200 bytes, the MTU is 1500 bytes, and the header is defined as 20 bytes, answer the following:
Will the TCP need to fragment the data? If yes, what will be the segment size that TCP decides to send?
Yes, TCP will need to fragment the data. The size of the segment that TCP will decide to send will be 1460 bytes, as this is the maximum size of data that can be transferred in a TCP segment without exceeding the MTU of the connection (1500 bytes) after the addition of headers.
If, during the acknowledgement of the first segment, the window size is changed to 2400 bytes and the congestion window is changed to 3200 bytes, what should be the size of the following segments?
After the window size is changed to 2400 bytes and the congestion window is changed to 3200 bytes, a total of 2000 more bytes can be sent, as this is the size of the new congestion window minus the size of the congestion window before the change (3200 – 1200 = 2000 bytes). Therefore, two segments with a size of 1460 bytes each and one segment with a size of 80 bytes can be sent.