+-------+        +--------+        +-------+
        |       |    lan1|        |lan2    |       |
H1 -----+Switch1+--------+ Router1+--------+Switch2+------H3
        |       |        |        |        |       |
H2 -----|       |        |        |        |       |
        +-------+        +--------+        +-------+
    |_________________|              |__________________|
        LAN1                              LAN2