o----------------------Service Layer----------------------o

+------+   +---+   +---+   +---+   +---+   +---+   +---+   +---+
|Classi|---|SF1|---|SF2|---|SF3|---|SF4|---|SF5|---|SF6|---|SF7|
|fier  |   +---+   +---+   +---+   +---+   +---+   +---+   +---+
+------+   
             <------VM1------>       <--VM2-->       <--VM3-->

   ^-----------------^-------------------^---------------^  Overlay 
                                                            Network
                                                            
   o-----------------o-------------------o---------------o  Underlay
                                                            Network
                                                            
   o--------o--------o--------o----------o-------o-------o  Link