Defeating TCP congestion-control mechanisms usually requires the explicit cooperation of the sender. However, consider the receiving end of a large data transfer using a TCP modified to ACK packets that have not yet arrived. It may do this either because not all of the data is necessary or because data that is lost can be recovered in a separate transfer later. What effect does this receiver behavior have on the congestion-control properties of the session? Can you devise a way to modify TCP to avoid the possibility of senders being taken advantage of in this manner?