This figure shows the configuration on APPHOST1 and APPHOST2. The Load Balancing Router is at the top, and listens on port 443. The port for the loop back from the Parallel Page Engine is 7777. The Invalidation port is 4001, and it is accessible only from inside the firewall. The URL for the Load Balancing Router is portal.mycompany.com:443. Two instances of OracleAS Web Cache are shown below the Load Balancing Router, each on its own computer, listening on port 7777. The URLs are apphost1.mycompany.com and apphost2.mycompany.com. Below the OracleAS Web Cache instances are two Oracle HTTP Server instances, both listening on port 7778. The URLs are apphost1.mycompany.com and apphost2.mycompany.com.