a) Figure 1 implies that Go Back-N is used because the given figure shows a cumulative acknowledgement which is a property of the Go Back-N protocol. Selective Repeat gives individual acknowledgements as the window shifts.
b) Since individual acknowledgements are shown in figure 2, it is Selective Repeat protocol being used in this figure.
c) Figure 2 depicts Selective repeat in which the sender window moves forward as it receives acknowledgement for the smallest sequence number in the window at that time. The receiver window in selective repeat moves forward as it receives data for the smallest sequence number in its window. So, at time t the sender window will start from 0 and go till 3 while receiver …show more content…
f) No, in that case they can’t have the same port number as then the server will not be able to differentiate between them anyhow.
Initial sequence number is chosen randomly. It is done this way to reduce the possibility of a packet which was being shared by the 2 host previously and got left in the network does not get received by any of these 2 hosts when they establish a new connection with each other again.
Essentially there are 3 messages shared between 2 hosts to establish a TCP connection.
First message contains the SYN bit, a randomly chosen sequence number and no data. This is sent from the host which wants to connect to the host with which it wants to connect. Let the host which wants to connect be HOST A and the host with which it wants to connect be HOST B
The second message is sent from host B to host A with a SYN bit , ACK bit with an ACK number 1 greater than the sequence number received from Host A, and an initial sequence number which is randomly