The most common topology places the ODR (or multiple ODRs) inside the private network between the Web server and the application servers. This leaves the Web server to continue serving static content, but the plug-in running on the Web server is now configured to route traffic to the ODR, rather than to the application servers. The ODR is constantly updated on the location of dynamic cluster instances within the cell (or cells), and routes traffic accordingly. Some less common topology options are also possible, including placing the ODR tier in the demilitarized zone, where it could be used in front of, or instead of the Web server tier.
:)
Nitin