226 The Practical OPNET User Guide for Computer Network Simulation
segments a TCP source can send. Initially, when a TCP connection begins
transmitting data, it goes into the Slow Start phase. During Slow Start,
the size of the congestion window grows exponentially until it reaches
the Slow Start Congestion Threshold (ssthresh). Once that happens, TCP
switches over to the Congestion Avoidance phase in which cwnd grows lin-
early. Typically, the initial value of cwnd is a congurable parameter, and
in OPNET, it is specied through the attribute Slow-Start Initial Count
(MSS). The initial value of Slow Start Congestion Threshold is set to the
smaller of 64KBytes and the Receive Buffer size at the destination host. In
TCP, a timeout occurs if ...