+----+  +-------+    +-------------------------------+-------+  +----+
| R1 |  |  R10  |    |                               |  R30  |  | R4 |
| L2 +--+ L1/L2 +------------------------------------+ L1/L2 +--+ L2 |
|    |  |       |    |                               |       |  |    |
+----+  ++-+-+--+-+  |                             +-+--+---++  +----+
         | | |    |  |                             |    |   |
         | +----------------------------------------------+ |
         |   |    |  |                             |    | | |
         |   +-----------------------------------+ |    | | |
         |        |  |                           | |    | | |
         |     +----------------------------------------+ | |
         |     |  |  |                           | |      | |
+----+  ++-----+- |  |                           | | -----+-++  +----+
| R2 |  |  R11  | |  |                           | | |  R31  |  | R5 |
| L2 +--+ L1/L2 +------------------------------------+ L1/L2 +--+ L2 |
|    |  |       | |  |                           | | |       |  |    |
+----+  ++------+------------------------------+ | | +----+-++  +----+
         |        |  |                         | | |      | |
         |        |  |                         | | |      | |
         |    +-------------------------------------------+ |
         |    |   |  |                         | | |        |
         |    |   |  |                         +----------+ |
         |    |   |  |                           | |      | |
         |    |   |  |                           +-----+  | |
         |    |   |  |                             |   |  | |
+----+  ++----+-+-+  |                             +-+-+--+-++  +----+
| R3 |  |  R12  |    |      L2 adjacency             |  R32  |  | R6 |
| L2 +--+ L1/L2 +------------------------------------+ L1/L2 +--+ L2 |
|    |  |       |    |                               |       |  |    |
+----+  +-------+----+                               +-------+  +----+