|<---------------------- (1) ---------------------->|
    |                                                   |
    | |<-------------------- (2) -------------------->| |
    | |                                               | |
    | |        |<----------- (3) ----------->|        | |
    | |        |                             |        | |
    | |        |  |<-------- (4) -------->|  |        | |
    | |        |  |                       |  |        | |
    V V   AC   V  V                       V  V   AC   V V
+-----+   |    +-----+                 +-----+    |   +-----+
|     |--------|     |                 |     |--------|     |
| CE1 |   |    | PE1 |. . . . . . . . .| PE2 |    |   | CE2 |
|     |--------|     |                 |     |--------|     |
+-----+   |    +-----+                 +-----+    |   +-----+
   ^              ^                       ^              ^
   |              |                       |              |
   |              |                       |              |
Customer       Provider                Provider       Customer
Edge 1         Edge 1                  Edge 2         Edge 2