Suppose a TCP connection has a window size of eight segments, an RTT of 800 ms, the sender sends segments at a regular rate of one every 100 ms, and the receiver sends ACKs back at the same rate without delay. A segment is lost, and the loss is detected by the fast retransmit algorithm on the receipt of the third duplicate ACK. At the point when the ACK of the retransmitted segment finally arrives, how much total time has the sender lost (compared to lossless transmission) if
(a) the sender waits for the ACK from the retransmitted lost packet before sliding the window forward again?
(b) the sender uses the continued arrival of each duplicate ACK as an indication it may slide the window forward one segment?