L bit=1   ----------+           +-----------+           +----------
                    |           |           |           |
L bit=0             +-----------+           +-----------+

D bit=1         +          +          +          +            +
                |          |          |          |            |
D bit=0   ------+----------+----------+----------+------------+-----

                             Traffic Flow
         ===========================================================>
L bit   ...1111111111 0000000000 11111111111 00000000000 111111111...

D bit   ...0000010000 0000010000 00000100000 00001000000 000001000...
         ===========================================================>