Consider the transfer of a file containing 1 million 8-bit characters from one station to another. What is the total elapsed time and effective throughput for the following cases?

a) A circuit-switched, star topology. Call setup time is negligible, and the data rate on the medium is 64 kbps.

b) A bus topology with two stations a distance D apart, a data rate of B bps, and a frame size P with 80 bits of overhead. Each frame is acknowledged with an 88-bit frame before the next is sent. The propagation speed on the bus is 200 m/ms. Solve for

D = 1 km, B = 1 Mbps, P = 256 bits

c) A ring topology with a total circular length of 2D, with the two stations a distance D apart. Acknowledgement is achieved by allowing a frame to circulate past the destination station, back to the source station. There are N repeaters on the ring, each of which introduces a delay of one bit time. Calculate for

D = 1 km, B = 1 Mbps, P = 256 bits, N = 10.