Web Performance Trainer will work in a variety of network configurations to fit your particular situation:

• LAN Testing
• Remote Testing
• Firewall Protected Web Server
  

LAN Testing

Web Performance Trainer runs on a "Test Computer" that will generate the virtual users that are directed at a Web server or servers to be tested. The most flexible configuration is also the easiest, where you can place the Test Computer on the same LAN as the Web server. This has the advantage of reducing network effects on the test because the full LAN bandwidth is available between Web Performance Trainer and the Web server.

Remote Testing

A common situation is where the person running the test is at another location than the Web server. There are two ways to handle this situation, which differ in the location of the software generating the virtual users. In the configuration shown below, Web Performance Trainer is run at one location, while the Web server can reside anywhere on a WAN, in another state, or even another country.

This configuration tests the performance of all networks between the computer generating the virtual user and the Web server, as well as the Web server itself. The number of virtual users you can simulate is limited by the bandwidth between the test computer and the Web server. For example, if the test computer is connected to the internet by DSL with a bandwidth of 200 KBytes per second, you would be able to simulate 40 56Kbit/sec modem connections, which have an affective bandwidth usage of 5Kbytes/sec.

One thing to watch for in this configuration is users at a company location typically share an internet connection, so a performance test would have to be performed when no one's using the network.

Larger simulations require that the dedicated bandwidth from test generating computer to the internet be at least as large as the network connection of the Web server. For example, if your Web server is connected to the internet by a T3, then the test generating computer has to be connected by a T3 dedicated to load testing.

One way to handle this configuration that eliminates most bandwidth restrictions is to use a remote playback engine. In this configuration Web Performance Trainer is split into two parts, a controller, and a playback engine. The playback engine is placed on a computer on the same LAN as the web server, while the controller remains in the remote location. The controller is used to remotely control the playback engine, keeping the heavy network load on the LAN, while allowing remote control over the test.

Note: In this configuration care should be taken to stop running the playback engine when its not being used for security reasons.

Firewall Protected Web Server

Firewalls complicate the testing procedure, both because they are barriers and because the performance of the firewall is unknown and therefore throws some level of uncertainty into the results. As a practical matter, however, Firewall performance only becomes an issue at very high loads, i.e. several thousands of simultaneous virtual users.

The most common use of the firewall is to protect the Web server by preventing all but basic HTTP access. The configuration shown below doesn't change the remote access situation if Web Performance Trainer is generating the virtual users remotely. The virtual users will access the web server just like any other user that is being let through the firewall to access the Web server.

The second type of firewall configuration (below) is where a virtual user generating engine is placed behind a firewall. This configuration is useful when a testing team at one corporate site is testing a private corporate intranet site at a remote corporate site.

Since the version 2.3, Web Performance Trainer supports remote controlling a single load generating engine.