Question

Suppose now the file is broken up into 1000 packets with each packet

containing 4,000 bits. Suppose that each packet is acknowledged by the
receiver and the transmission time of an acknowledgement packet is
negligible. Finally, assume that the sender cannot send a packet until the
preceding one is acknowledged. How long does it take to send the file?

Answer 1

The delay to send each packet will be ttrans + tprop. However there is an additional tprop delay for the acknowledgement packet to arrive at the sender, prior to which the next packet can be transmitted. Hence the total delay to transmit 10 packet is = 10 * (ttrans + 2 tprop) = 10*(40 msec + 80 msec) = 1.2 sec

Step-by-step explanation: