From forouzan :: TCP/IP protocol suite:
If three duplicate ACKs are received, there is a weaker possibility of congestion; a segment may have been dropped but some segments after that have arrived safely since three duplicate ACKs are received. This is called fast transmission and fast recovery. In this case, TCP has a weaker reaction as shown below:
(A). It sets the value of the threshold to half of the current window size.
(B). It sets cwnd to the value of the threshold (some implementations add three segment sizes to the threshold).
(C). It starts the congestion avoidance phase.
Is the Value of Sender Window(SW) is correct during 3 duplicate Acks arrival?
U mean to say During the phase when 3 duplicate acks are coming sender opts for additive increase and After the 3 duplicate Acks arrived sender opts for slow start??
No, i am saying whenever timeout occurs it means congestion is severe slow start mechanism happens.
After the 3 duplicate Acks arrived sender opts for slow start(This is wrong)