(Figure 3)                              (Figure 4)
     +----------------+                          +--------+
     | Control-Client |  <-- TWAMP-Control -->   | Server |
     +----------------+                          +--------+ 
             ^                                        ^
             |                                        |
             V                                        V
     +----------------+                     +-------------------+
     | Session-Sender |  <-- TWAMP-Test --> | Session-Reflector |
     +----------------+                     +-------------------+
         (Figure 5)                               (Figure 6)