Calculate the total time to transfer a 800000B file in the f

Calculate the total time to transfer a 800,000B file in the following cases, assuming a RTT of 120ms, a packet size of 1, 600B data a) The bandwidth is 1.2Mbps and data packets can be sent continuously b) The bandwidth is 1.6 Mbps, but after we finish sending each data packet we must wait one RTT before sending the next c) The bandwidth is \"infinite\", meaning that we take transmit time to be zero, and up to 20 packets can be sent per RTT. d) The bandwidth is infinite, and during the first RTT we can send one packet, during the second RTT we can send three packets, during the third we can send nine, then twenty seven, and so on.

Solution

no of packets=msg size/packet size=800000B/1600B=500

1>

bandwith =1.2 Mbps

mean 1sec=1.2*10^6 bits=1200000bits

1 bit=1/1200000sec

then 1600B=1600*8/1200000 sec=4/375 =10.6ms

500 packet=10.6*500 ms=5300 ms

2> due to 500 packet

time between transmission= 499*120ms=59880ms

bandwith =1.6 Mbps

mean 1sec=1.6*10^6 bits=1600000bits

1 bit=1/1600000sec

then 1600B=1600*8/1600000 sec=1/125 =8ms

500 packet=8*500 ms=4000 ms

total time = 4000+59880=63880ms

3>20pkt/RTT

1RTT=20pkt

500packet=(1/20)*500 RTT=25*120=2650ms

4>

total RTT required= 1+3+3^2+3^3....

(1*3^n)/3=500

n=7RTT=840ms