Suppose two hosts, A and B, are separated by 15,000 kilometers and are connected by a direct link of R = 5 Mbps. Suppose the propagation speed over the link is 2.5 * 108 meters/sec. How long does it take to send a 1,500,000 bit file, assuming it is sent continuously?

360 msec

Explanation:

Data provided in the question:

Distance between the two hosts = 15,000 kilometer

= 1.5 * 10⁷ m [ ∵ 1 km = 1000 m ]

Transmission rate, R = 5 Mbps = 5 * 10⁶ bits per second

Propagation speed over the link = 2.5 * 10⁸ meters/sec

Size of file to be sent = 1,500,000 bit

Now,

Propagation delay (dprop)

= Distance : Speed

= (1.5 * 10⁷) : (2.5 * 10⁸)

= 0.06 sec

= 60 msec [ ∵ 1 sec = 1000 millisecond ]

Transmission delay (dtrans)

= Size of file : Rate of transmission

= 1500000 : (5 * 10⁶)

= 0.3 sec

= 300 msec

Therefore,

Time required for transmitting the file

= Propagation delay + Transmission delay

= 60 msec + 300 msec

= 360 msec