+----------- Inter DC ----------------+
           (4)    |                (5)                  |
+------+  ---->   | +---------+   ---->     +---------+ |
|      |   NSH    | |         |     SR      |         | |
+ SFF1 +----------|-+ DC1-GW1 +-------------+ DC2-GW1 + |
|      |          | |         |             |         | |
+------+          | +---------+             +---------+ |
                  |                                     |
                  |          +------------+             |
                  |          | S(DC2-GW1) |             |
                  |          +------------+             |
                  |          | N(100,254) |             |
                  |          +------------+             |
                  |          | F:Inner Pkt|             |
                  |          +------------+             |
                  +-------------------------------------+