continue;
long initial_seqno=val.high_seqno; // val.getHighestDeliveredSeqno();
NakReceiverWindow win=(NakReceiverWindow)received_msgs.get(sender);
if(win != null) {
win.reset(); // stops retransmission
received_msgs.remove(sender);
}
win=createNakReceiverWindow(sender, initial_seqno);
synchronized(received_msgs) {
received_msgs.put(sender, win);