question on redundant nginx reverse proxy setup

[Simon Cornelius P Umacob]

Hi,

I'm planning to set up this environment:

+-------------+              +-------------+
|    ISP1     |              |    ISP2     |
+-------------+              +-------------+
       |                            |
+-------------+              +-------------+
|  FW1/proxy  |              |  FW2/proxy  |
+-------------+              +-------------+
     |  |                          |  |
     |  +--------------+-----------+  |
     |                 |              |
     |              switch            |
     |                 |              |
     +----+------------+--------------+
          |            |
       switch          |
          |            |
          |            +---------------+
          |                            |
+---------+---+              +---------+---+
|    www1     |              |    www2     |
+-------------+              +-------------+

(raw ASCII art at http://simoncpu.pastebin.com/raw.php?i=0StGLjCk)

Question: Does nginx gurantee, using the NginxHttpUpstreamModule, that
it will direct incoming connections to the right www server?  Would
the two identical nginx servers create identical IP hashes?

Thanks,

[ simon.cpu ]