+=======+  
              | INIT  |       FCN!=0 & more frags
              |       |       ~~~~~~~~~~~~~~~~~~~~~~
              +======++  +--+ send Window + frag(FCN)
                 W=0 |   |  | FCN-
  Clear lcl_bm       |   |  v set lcl_bm
       FCN=max value |  ++==+========+
                     +> |            |
+---------------------> |    SEND    |
|                       +==+===+=====+
|      FCN==0 & more frags |   | last frag
|    ~~~~~~~~~~~~~~~~~~~~~ |   | ~~~~~~~~~~~~~~~
|               set lcl_bm |   | set lcl_bm
|   send wnd + frag(all-0) |   | send wnd+frag(all-1)+RCS
|       set Retrans_Timer  |   | set Retrans_Timer
|                          |   |
|Recv_wnd == wnd &         |   |  
|lcl_bm==recv_bm &         |   |  +----------------------+
|more frag                 |   |  | lcl_bm!=rcv-bm       |
|~~~~~~~~~~~~~~~~~~~~~~    |   |  | ~~~~~~~~~            |
|Stop Retrans_Timer        |   |  | Attempt++            v
|clear lcl_bm              v   v  |                +=====+=+
|window=next_window   +====+===+==+===+            |Resend |
+---------------------+               |            |Missing|
                 +----+     Wait      |            |Frag   |
not expected wnd |    |    Bitmap     |            +=======+
~~~~~~~~~~~~~~~~ +--->+               ++Retrans_Timer Exp  |          
    discard frag      +==+=+===+=+==+=+| ~~~~~~~~~~~~~~~~~ |
                         | |   | ^  ^  |reSend(empty)All-* |   
                         | |   | |  |  |Set Retrans_Timer  |
                         | |   | |  +--+Attempt++          |
  C_bit==1 &             | |   | +-------------------------+
Recv_window==window &    | |   |   all missing frags sent
             no more frag| |   |   ~~~~~~~~~~~~~~~~~~~~~~
 ~~~~~~~~~~~~~~~~~~~~~~~~| |   |   Set Retrans_Timer 
       Stop Retrans_Timer| |   |    
 +=============+         | |   |
 |     END     +<--------+ |   |
 +=============+           |   | Attempt > MAX_ACK_REQUESTS
            All-1 Window & |   | ~~~~~~~~~~~~~~~~~~
               C_bit ==0 & |   v Send Abort
          lcl_bm==recv_bm  | +=+===========+
              ~~~~~~~~~~~~ +>|    ERROR    |
                Send Abort   +=============+