Multiple server deployment: Multiple (two or more) Access Manager instances are deployed on at least two different host servers. For example, you might deploy two instances on one server and a third instance on another server. Or you might deploy all instances on different servers. You can also configure the Access Manager instances in session failover mode, if required for your deployment.
Load balancer: One or more load balancers route client requests to the various Access Manager instances. You configure each load balancer according to your deployment requirements (for example, to use round-robin or load average) to distribute the load between the Access Manager instances. A load balancer simplifies the deployment, as well as resolves issues such as a firewall between the client and the back-end Access Manager servers.
You can use a hardware or software load balancer with your Access Manager deployment. For example, for information about the Application Server Load Balancing Plug-in, see the Sun Java System Application Server Enterprise Edition 8.2 Quick Start Guide.
Directory Server: All Access Manager instances access the same Directory Server.