04 Try it yourself Interactive

Step the window one round trip at a time

One column per round trip, height proportional to cwnd, with the ssthresh line drawn across the plot so you can watch it drop when a loss happens. Indigo columns are rounds spent in slow start, blue columns are congestion avoidance, amber is the round you are on, and rose is a round that ended in a loss. The two tabs run the same loss script through TCP Reno and TCP Tahoe, so switching tabs changes nothing except the rule applied at the triple duplicate ACK, which is the point. Every value is recomputed from the rules in section 03 rather than stored, so a script you type yourself is derived the same way the presets are. Nothing plays on its own: Next, Back and Reset, or the arrow keys.

TCP Reno · 8d, 11t
nothing sent yet
Write each loss as a round number then d for three duplicate ACKs or t for a timeout. Rounds 1 to 14. ssthresh starts at 8 MSS.
slow start congestion avoidance this round loss at the end of this round
Press Next to begin. Each press advances the connection by one round trip.


      

        
Round–

        
cwnd (MSS)–

        
ssthresh–

        
Phase–

      


      

      

        
        
        
        round 0 / 15