+---------+        +--------+        +--------+          +--------+
 |         +--------+        |        |        +----------+        |
 | OTN     |--------| OTN    |        | OTN    |----------| OTN    |
 | Switch  +--------+ Regen  +--------+ Regen  +----------+ Switch |
 | A       |        | B      |        | C      |          | D      |
 |         +--------+        |        |        +----------+        |
 +---------+        +--------+        +--------+          +--------+

     <-------------------------ODUCn-------------------------->
      <---------------><-----------------><------------------>
           OTUCn              OTUCn               OTUCn