congestion control in tcp

consider the effect of using slow start on a line of propagation delay of 10ms. the reciever window is 24kB and the maximum segment size is 2kB how long does it take to send full window size segement in ms with initial threshold of 20KB?


Niket Gangwar @niket151194
20 Oct 2017 06:33 pm

You have to differentiate whether question asks for after how many RTTs the size will become so and so OR after how many RTTs we will be able to send the segment of so and so size completely. Accordingly calculate the time required.

Here for example:-  how long it wlll take to send full window size.

Th= 20 KB

Initially in Slow start phase..

2 | 4 | 8 | 16 | 20 | 22| 24 | ... which means after 6 RTTs we have the  window of size 24 KB but it is after 7 RTTs only that the window of 24KB will be sent completely. So answer would be 7 RTTs = 7* 2 * Tp = 7*20= 140 ms.


nikita mehrotra @nikitamehrotra
20 Oct 2017 03:53 pm

but here after threshold the size shoud increase linearly i.e. 1mss so how it is 24 after 20

Niket Gangwar @niket151194
20 Oct 2017 06:32 pm

Oh.. yes it was a mistake ... I corrected it...  

Two answers possible coz of whether to consider the last RTT or not.. Even in 2014 IITs released two answers in their key.