+--------+         +----+        +----+         +-------+
|        |         |    |        |    |         |       |
| Sender +---------+ R1 +--------+ R2 +-------- + Dest. |
|        |         |    |        |    |         |       |
+--------+  MTU-S  +----+  9000B +----+  MTU-D  +-------+