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# Configure multiple IP addresses

This section describes to use multiple IP addresses in your performance tests to reflect real-world situations.

In this topic:

## Multiple IP addresses overview

Application servers and network devices use IP addresses to identify clients. The application server often caches information about clients coming from the same machine. Network routers try to cache source and destination information to optimize throughput. If many users have the same IP address, both the server and the routers try to optimize. Since Vusers on the same load generator have the same IP address, server and router optimizations do not reflect real-world situations.

The Multiple IP Addresses feature enables Vusers running on a single load generator to be identified by many IP addresses. The server and router recognize the Vusers as coming from different load generators and as a result, the testing environment is more realistic.

This feature can be implemented on Windows and Linux platforms with the following protocols:

DNS, IMAP, Oracle NCA, Oracle Web Applications 11i, POP3, RTE, SAP-Web, Siebel-Web, SMTP, Web (HTTP/HTML), Web Services, and Windows Sockets.

Note: IP spoofing should be turned off for Dockerized load generators.

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## Enable IP spoofing

The following steps describe how to add IP addresses to a load generator to enable IP Spoofing.

1. Create multiple IP addresses on the load generator

   - Windows: Run the IP Wizard to create multiple IP addresses. For details on running the IP Wizard, see IP Wizard.

     The new IP addresses are added to the load generator once and are used for all performance tests. After running the wizard, restart the load generator machine.

   - Linux: Manually configure the new IP addresses for Linux load generators. For details, see Configure multiple IP addresses on Linux.

     Note: Support for the IPv6 format has not been certified for IP spoofing.

2. Update the server's routing table with the new addresses

   After the client machine has new IP addresses, the server needs the addresses in its routing table, so that it can recognize the route back to the client. If the server and client share the same netmask, IP class, and network, the server's routing table does not require modification.

   Note: If there is a router between the client and server machines, the server needs to recognize the path using the router. Make sure to add the following to the server routing table:

   - A route from the web server to the router,

   - Routes from the router to all of the IP addresses on the load generator.

   Update the web server routing table as follows:

   1. Edit the batch file that appears in the IP Wizard Summary page.

   2. For each occurrence of [CLIENT_IP], insert your IP address instead.

   3. Run the batch file on the server machine.

3. Enable the Multiple IP Addresses feature

   After you define multiple IP addresses, you set an option to tell the Controller to use this feature.

   1. Click the Navigation menu and select Test Management > Tests & Scripts. Select a performance test in the test management tree and click Edit Test. In the Groups and Workload tab, click the Test Options button in the Groups pane toolbar, and in the General section select Enable IP Spoofer.

   Note: You must select this option before running a performance test.

   1. Specify how the Controller allocates the IP addresses: per process or per thread. For details, see the Controller's general run option settings described in Configure IP spoofing and advance warning settings.

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## Configure multiple IP addresses on Linux

The following section describe how to manually configure multiple IP addresses on the Linux load generator.

1. To define multiple IP addresses for a single Ethernet card, you need IP Aliasing compiled into the kernel. To do this, use the ifconfig command: /sbin/ifconfig eth0:0 x.x.x.x netmask 255.255.x.x up

1. Substitute the new IP address for x.x.x.x, and insert the correct information for subnet mask. Place this command in the rc.local file so that it runs on boot.

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## IP Wizard

This wizard enables you to create and save new IP addresses on Windows machines.

The following guidelines apply:

- The IP wizard resides on each load generator.

- The new addresses can be a range of addresses defined by the Internet Assignment Numbers Authority. They are for internal use only, and cannot connect to the Internet. This range of addresses is the default used by the IP Wizard.

- The IP Wizard only works on machines with a fixed IP, not on machines with a DHCP.

- Before any of the changes can take effect, you must restart the machine after you run the wizard, and the web server's routing table may need to be updated.

Open the wizard in one of the following ways:

- From the Start menu, open OpenText Enterprise Performance Engineering Host > Tools > IP Wizard.

- From the Host's \bin directory, run ipwizard.exe.

IP Wizard Welcome - Step 1 of 3

User interface elements are described below.

UI Elements | Description
--- | ---
Create new settings | Enables you to define new IP settings on the load generator.
Load previous settings from file | Enables you to use an existing file with IP address settings.
Restore Original Settings | Restores original settings.

IP Wizard - Step 2 of 3 (Optional)

User interface elements are described below (unlabeled elements are shown in angle brackets):

UI Elements | Description
--- | ---
<Web Server Address box> | If you have more than one network card, enables you to choose the card to use for IP addresses. This step enables the IP Wizard to check the server's routing table to see if it requires updating after new IP addresses are added to the load generator. For details, see Update the server's routing table with the new addresses.

IP Wizard - Step 3 of 3 (Optional)

User interface elements are described below.

UI Elements | Description
--- | ---
Add | Opens the Add dialog box, enabling you to add a new IP address. Private Address Spaces. The class that represents the correct submask for the machine's IP addresses. From IP. Adds IP addresses starting with this number. Submask. IP addresses include two components, a netid and hostid. The submask determines where the netid portion of the address stops and where the hostid begins. Number to add. The number of IP addresses to add. Verify that new IP addresses are not already in use. Instructs the IP Wizard to check the new addresses. The IP Wizard adds only the addresses that are not already in use.
Remove | Removes a selected IP Address.
IP Address | The IP addresses on the load generator machine.
Subnet Mask | The submasks of the IP addresses on the load generator machine.
Number of IPs added | The number of IP addresses added to the load generator machine.

IP Wizard - Summary

User interface elements are described below (unlabeled elements are shown in angle brackets).

UI Elements | Description
--- | ---
<Summary area> | Displays a summary of the operations performed by the IP Wizard. Take note of the location of the batch file (.bat). This is used to update the routing table if necessary. See Enable IP spoofing.
Reboot now to update routing tables | If you updated the routing table, restarting initializes the Windows device drivers with the new addresses.

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See also:

- Tests
- Configure multiple IP addresses

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