title: is sliding window protocol needs full duplex data flow?
body: <p>Here is my question, in sliding window protocol for flow control in l2 osi model, it is necessary to establish a full duplex connection?
  because i think at the same time that frames are sending ACK from receiver should transmit for example if window size is 5 when 3th frame is sending ACK of 1th one should sent by receiver!
  that is right??</p>