| *****  B-F WDM Path
                                         | @@@@@  B-E WDM Path
                                         | $$$$$  A-E WDM Path
                                         o--------------------

  +---+        /-\ $$$$$$$$ /-\ $$$$$$$$$ /-\          +---+
  | R1|-------( A )--------( C )---------( E )---------| R3|
  +---+        \-/         @\-/ @@@@@@@@@ \-/          +---+
                          @/   \         /   \
                         @/     \       /     \
                        @/       \     /       \
                       @/         \   /         \
                      @/           \ /           \
      +---+          /-\ ********* /-\ ********* /-\          +---+
      | R2|---------( B )---------( D )---------( F )---------| R4|
      +---+          \-/           \-/           \-/          +---+