hardware load balance for gateways.

[ricky_ru]

Dears,

We have a system design as below:
f5 hardware loadbalance -------->gateway1(IHS in aix server)---------->dispatcher1&CM1(ATC in machine 1)
                                   -------->gateway2(IHS in aix server)---------->dispatcher2&CM1(ATC in machine 2)

The F5 load balance is above the gateways. It sends requests to gateway1/gateway2.
From this link http://www-01.ibm.com/support/docview.wss?uid=swg21341010, it states the following:
Within Cognos Configuration on each Report Server (Application Tier Component server), ensure the following settings are in place:
a) External dispatcher URI - should point to itself as usual
b) Internal dispatcher URI - should point to itself as usual
c) Gateway URI - this should point to the load balancer for the web servers
As to the third point, in the ATC machines(machine 1 and 2), in the cognos configuration, the Gateway Settings->Gateway URI should be filled with the f5 hardware loadbalance address?  I do not know the reason. 
What's function of this value? What is the right value to set in this case?.

Below is the explanation in cognos configuration:
<!-- gateway: Specifies the URI to the gateway.  -->
<!-- The gateway must be located on the same computer as a Web server. If you are using
       ISAPI, change 'cognos.cgi' to 'cognosisapi.dll'. If you are using apache_mod, change
       'cognos.cgi' to 'mod_cognos.dll' on Windows, to 'mod_cognos.sl' on HP UX PA-RISC,
       or to 'mod_cognos.so' otherwise. Use the 'https' or 'http' protocol to select SSL
       or non-SSL communication. The host name portion of the gateway URI must be changed
       from localhost to an IP address or a network host name.  -->

Thanks!