Tag Archive: Load Testing

Working with a firewall means that you can prevent unauthorized access to or from a private network, on specific port numbers.

In a regular LoadRunner load test scenario (not over a firewall), the Controller has direct access to the LoadRunner agents running on remote machines. This enables the Controller to connect directly to those machines. When running Vusers or monitoring applications over a firewall, this direct connection is blocked by the firewall. The connection cannot be established by the Controller, because it does not have permissions to open the firewall.

LoadRunner solves this problem by using a communication configuration based on HTTPS or secured TCP/IP. This configuration uses the standard SSL port on the firewall (port 443).

A LoadRunner agent is installed on load generators running Vusers over a firewall, and on Monitor Over Firewall machines that monitor the servers that are located over a firewall. The agent communicates with the MI Listener machine through port 443 in the firewall. The MI Listener is a component that serves as router between the Controller and the LoadRunner agent.

When the LoadRunner agent connects to the MI Listener, the MI Listener keeps a listing of the connection to the agent using a symbolic name that the agent passed to it. When the Controller connects to the MI Listener, it communicates to the MI Listener through port 50500.

Setting Up your System to Use Firewalls:

Basic Steps Setting up your system to use firewalls involves the following stages of configuration: Installation and initial configuration Running Vusers over a firewall Installation and initial configuration

To enable over-firewall communication, ensure that you have installed the following LoadRunner components:

MI Listener Monitor Over Firewall component To perform initial configuration of your over-firewall system:

1 Configure your system according to TCP or HTTPS.

2 Modify your firewall settings to enable communication between the machines on either side of the firewall.

3 Configure the MI Listener.

Configuring the MI Listener To configure the MI Listener:

1 Open incoming HTTPS service for port 443. The port settings are set by your system administrator.

2 Stop the LoadRunner agent on the MI Listener machine by right-clicking its icon in the system tray and selecting Close from the popup menu.

3 Run MI Listener Configuration from Start > Programs > LoadRunner > Advanced Settings, or run \launch_service\bin\MILsnConfig.exe.

4 Set each option as described in the following table:

5 Click OK to save your changes, Cancel to cancel them, or Use Defaults.

6 Restart the LoadRunner agent by double-clicking the shortcut on the desktop, or choosing Start > Programs > LoadRunner.

7 Make sure that port 443 is free on the MI Listener machine.

Running Vusers over a firewall

To set up your system to run Vusers over a firewall:

1 On each load generator machine that will be running over a firewall, configure the LoadRunner agent to communicate with the MI Listener.

2 Configure the Controller machine to recognize the load generator and MI Listener machines.

Configuring LoadRunner Agents Over the Firewall

1 Stop the LoadRunner agent by right-clicking its icon in the system tray and selecting Close.

2 Run Agent Configuration from Start > Programs > LoadRunner > Advanced Settings, or run \launch_service\bin\AgentConfig.exe.

3 Select the Enable Firewall Agent check box, and then click Settings. The Agent Configuration dialog box opens.

4 Set each option as described in “Agent Configuration Settings”

5 Click OK to save your changes, or Cancel to cancel them.

6 Restart the LoadRunner agent by double-clicking the shortcut on the desktop, or select Start > Programs > LoadRunner > LoadRunner Agent Service/Process.

7 Check the connection status between the LoadRunner agent and the MI Listener.

Configuring the Controller for Running over a Firewall

1 Run the Controller from Start > Programs > LoadRunner > Applications > Controller and create a new scenario, or load an existing one.

2 Click Generators to display the Load Generators window. In the Name field, enter the symbolic name of the server. This is the same name that you entered in the Local Machine Key setting in the Agent Configuration.

3 Select the Load Generator, and click Details to display the Load Generator Information.

4 In the Security tab, enter the MI Listener machine’s name in the MI Listener field. This is the same name that you entered in the MI Listener Name setting of the Agent Configuration dialog box. In this example, the MI Listener is bunji.

5 In the Firewall Settings section, select one of the following options: ➤ Enable running Vusers over Firewall. To run Vusers over the firewall. ➤ Enable Monitoring over Firewall. To monitor Vusers over the firewall.

6 Click OK to return to the Load Generators dialog box.

7 Select the load generator and click Connect. This will do all the setup required to run your test over the firewall…

There is a simple way to examine, whether the load test which we conducted is to a real extent or not.


The factors which we have to capture is


Hits per second,

Avg Response time,

Think Time

No of users simulated.


Thus substituting all the gathered data in the formula,


Total Number of users executed = (Response Time + Think Time) * Request per second



Thus while calulating using the formula, the result value should equal or should be greater than the total number of users executed.


From this deal we can able to find out, how much users the servers can handle. If the result value goes below the total numbers executed, then the servers are not capable to server these many users.


The Page size also can be verified using,


Page size = Throughput / Hits per second.

By using Little’s lax, we can determine the number of users in the system.

Number of virtual users going to be simulated.
Throughput (bytes)

By using Little’s Law, we can find the following:
Actual Number of users in the System = (Response Time + Think Time) * Transactions per Second