Consider sending a large file from a host to another over a TCP connectionthat has no loss.a. Suppose TCP uses AIMD for its congestion control without slow start.Assuming cwnd increases by 1 MSS every time a batch of ACKs is receivedand assuming approximately constant round-trip times, how long does it takefor cwnd increase from 1 MSS to 6 MSS (assuming no loss events)?b. What is the average throughout (in terms of MSS and RTT) for this connectionup through time = 5 RTT?
Given : TCP uses AIMD for its congestion control without slow start.
Also given congestion window(cwnd) increases by 1MSS everytime a batch of ACK is received
a. Time taken for cwnd to increase from 1MSS to 6MSS :
It takes , 1 RTT for cwnd to increase from 1to 2 MSS
2 RTT for cwnd to increase from 2 to 3 MSS
3 RTT for cwnd to increase from 3 to 4 MSS
4 RTT for cwnd to increase from 4 to 5 MSS
5 RTT for cwnd to increase from 5 to 6 MSS
therefore it takes 5 RTT's to increase cwnd from 1 to 6 MSS.
b. We know average throughput = total data/total time
So in the 1st RTT 1 MSS was sent
2nd RTT 2 MSS was sent
3rd RTT 3 MSS was sent
4th RTT 4 MSS was sent
5th RTT 5 RSS was sent
Total data sent = 1+2+3+4+5
= 15MSS
Total time = 5RTT's
therefore average throughput = 15/5
= 3 MSS per RTT
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