In this illustration, a load balancer sits above two single sign-on middle tier computers. Arrows running from the load balancer to these computers indicatethat it serves both middle tiers. Atop the load balancer sits the browser. Beneath the middle tiers is a dotted line box containing the Oracle Internet Directory server and the identity management infrastructure database. The dotted line box indicates that the directory server and infrastructure database reside on thesame computer. Arrows running from the single sign-on middle tiers to the directory server indicate that the directory serves both middle tiers.