Many people ask how they should implement hardware-based load balancers into an Oracle Access Manager (OAM) implementation. As a rule of thumb: load balancers should be placed in front of the web/application servers where the web gates are installed (i.e., between the browser and the web server) and that is it. OAM has built-in load balance functionality and can manage fail-over on its own. This is referred to as software-based load balancing.
I have seen some environments where clients have put load balancers in between the Identity/Access servers and their directory servers. With OAM this is unnecessary and not advised. According to Oracle documentation,
“performance can be negatively affected by the load balancer, which can terminate a connection but fail to trigger a response that OAM can adjust to. This can cause outages.”
– Performance Tuning 3-39, http://download.oracle.com/docs/cd/E12530_01/oam.1014/e10353.pdf