Consider the transfer of a file containing one 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 local network. Call setup time is negligible and the data rate on the medium is 64 kbps. b)A bus topology local network with two stations at distance D apart, a data rate of B bps and a frame size of P with 80 bits of overhead per frame. Each frame is acknowledged with an 88-bit frame before the next is sent. The propagation speed on the bus is 200m/us. Solve for: 1. D = 1 km, B = 1 Mbps, P = 256 bits 2. D = 1 km, B = 10 Mbps, P = 256 bits 3. D = 10 km, B = 1 Mbps, P = 256 bits 4. D = 1 km, B = 50 Mbps, P = 10 kbits