public AckMcastSenderWindow(RetransmitCommand cmd) { this(cmd, RETRANSMIT_TIMEOUTS);
public AckMcastSenderWindow(RetransmitCommand cmd, long[] retransmit_intervals, TimeScheduler sched) { init(cmd, retransmit_intervals, sched, false);
    public AckMcastSenderWindow(RetransmitCommand cmd) {	this(cmd, RETRANSMIT_TIMEOUTS);    }