.................................
       .                 +---+         .
       .    +------------| C1|----+    .            
       .    |            +---+    |    .  
       .    |                     |    .
+--+   .  +-+-+      +---+      +-+-+  .   +--+  
|S2|------|G2 |------| C3|------|G1 |------|S1|
+--+   .  +-+-+      +---+      +-+-+  .   +--+ 
       .  CPE2                   CPE1  .  
       .    |            +---+    |    . 
       .    +------------| C2|----+    . 
       .                 +---+         . 
       '...............................'
              DOTS Client Domain