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Assume the scenario where size of the congestion window of a TCP connection be 40KB when timeout occurs. The MSS is 2KB. Propagation delay be 200msec. Time taken by TCP connection to get back to 40KB congestion window is …...

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thresh hold =40/2= 20 kb
                                                        time out then it will incremented by 2
the seq goes like this 2 | 4 | 8 | 16 | 20 |  22 | 24 | 26 | 28 | 30 | 32 | 34 | 36 | 38 | 40|

so total will be number of times | occurs * rtt

so total will be 15*400=6000 msec
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We send data in terms of MSS AND NOT KB SO WHENEVER DATA IS GIVEN IN TERMS OF KB,CONVERT IT TO MSS.
Here, it has been said that MSS is 2KB ==> It means the size of 1 segment is 2KB (Max.)
congestion window of a TCP connection be 40KB ===> 40KB/2KB = 20MSS
Threshold = 10MSS

You can either take the window Size in KB OR CONVERT IT TO MSS.....
2KB = 1MSS

1MSS = 2KB
2MSS = 4KB
4MSS = 8KB
8MSS = 16KB
10MSS = 20KB
11MSS = 22KB
12MSS = 24KB
13MSS = 26KB
14MSS = 28KB
15MSS = 30KB ...............

After RTT = 2*200 * 14 = 5600ms, we are able to achieve the Windows Size of 40KB and after RTT = 6000ms, we were able to send
20MSS OR 40KB DATA IN ONE WINDOW SUCCESSFULLY.

But Question is asking
Time taken by TCP connection to get back to 40KB congestion window is …...

it should be 5600ms.

I hope I am clear.
edited by

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