Q64

Suppose that it takes $1$ unit of time to transmit a packet (of fixed size) on a communication link. The link layer uses a window flow control protocol with a window size of $N$ packets. Each packet causes an ack or a nak to be generated by the receiver, and ack/nak transmission times are negligible. Further, the round trip time on the link is equal to $N$ units. Consider time $i > N$. If only acks have been received till time i(no naks), then the goodput evaluated at the transmitter at time i(in packets per unit time) is