Consider the following plot of TCP window size as a function of time. Assume TCP is operating with slow start, congestion avoidance, fast retransmit and fast recovery mechanism.
What is the time interval where the slow start runs again because of a time-out and because of 3 ACKs respectively ?
A 16, 22
B 23, 17
C 17, 23
D 17, 22
If a time out occurs there is a stronger possibility of congestion, hence TCP reacts strongly. It sets the value of threshold to one-half of current window size. Set cwnd to size of one segment and starts slow start phase again.
If three ACKs are received, there is a weaker possibility of congestion, a segment may have been dropped. Hence TCP has a weaker reaction. It sets value of threshold to half of current window size. It sets cwnd to the value of threshold. It starts congestion avoidance phase again.
Please explain in more details about the concept underlying?