Environment
Our WebSphere Application Server environment consisted of an IBM® System z™ and an IBM eServer™ xSeries® server and client.

The System
z contained a z/VM® LPAR with seven guests. The network
was split into three parts:
- The xSeries and the System z systems were connected in the unsecure external zone through an Extreme Mariner Switch. The xSeries system contained the WebSphere Studio Workload Simulator, which drove the Trade clients and generated the workload.
- The DMZ contained one guest with the WebSphere Caching Proxy Server protected from the external zone with a less restrictive firewall (Firewall 2) running in a separate guest. It is implemented as a z/VM guest LAN.
- The trusted internal zone, the second z/VM guest LAN, is protected with
another guest with a more restrictive firewall (Firewall 1) and contains one
guest for each of the following servers:
- WebSphere Load Balancer
- Apache Web Server
- WebSphere Application Server
- The DB2® UDB database server
The environment we used for our WebSphere Application Server clusters testing is shown in Figure 2.

This test environment was very similar to our single WebSphere Application Server test environment (see Figure 1). Added to this environment were three additional WebSphere nodes so that z/VM contained up to ten guests. The first WebSphere node hosted the Deployment Manager, which was required to create the cluster.