The LNS Nodal test case tests an LNS's capability to establish L2TP tunnels and L2TP sessions for MNs. This topic will guide you through configuring and running a basic Capacity Test, and then expanding the basic test with the optional behaviors available in the test case.
After you have a functioning test session, you can build tests using other test activities and options:
You should have a basic understanding of the test system:
Prepare the system and gather information about the SUT
Add the SUT to the database if necessary
The LNS SUT's L2TP and PPP requirements
To configure an LNS Nodal Capacity test:
The goal for the first test is to establish one L2TP tunnel and one MN session within the tunnel to confirm the test case definition, then to successfully execute the test with increased rates and multiple sessions, and finally, to customize the more advanced protocol, MN, and test case behaviors.
Create a new test session... and add an LNS Nodal test case... from the Basic library. The Test Case Settings window... opens to the General tab.
Devices and Addresses — Identify the SUT and define the LAC emulator
On the General tab, select the SUT from the L2TP drop-down list in the System Under Test pane.
Define the LAC node in the LAC Node Group sub-tab. Select a Physical Interface and the first address in the interface's pool is displayed in Starting IP Address. This test will only use one LAC node.
If the routing defined on the test server encompasses the SUT, accept the Default Routing setting. Otherwise, select Specify Next Hop IP Address and enter the next hop address in the adjacent field.
PPP Parameters — Define the synchronization mode, control protocol, and authentication
On the PPP tab, modify the default Magic Number... if necessary.
Select the Network Control Protocol... and enable Van Jacobson Compression... if it is required when IPCP is used.
If the SUT requires that authentication is performed, select the Authorization type on the PPP tab and configure User Name and Password... with values that will be acceptable to the device performing the authentication. The Auto-Increment feature gives you the ability to provision a unique User Name for each MN session.
Select the Synchronization Mode, and configure ACCM if necessary.
L2TP Parameters — Define the L2TP tunnel and session settings
Confirm that the SUT L2TP Port Number is compatible with the SUT, and modify it if necessary.
If authentication is used, check the Enable Tunnel Authentication box and enter a Password. When challenge-response authentication is used, check the Require Authentication box and set the Send Challenge Size.
You are now ready to test your configuration. The parameters that have not been addressed control optional behaviors that do not affect the success of a session. Click OK to accept the test case. If any parameters fail validation, you will receive an error indicating the problem parameter. Correct the problem and when the definition is accepted, the test case is listed in the Test Session window.
Run the test session, and a validation check is performed on the test session. This validation ensures that the IP addresses used by the test case do not conflict with any other test sessions that may be running on the test server, and that the test definition does not violate rate and volume limits. You will also receive an error if you attempt to run the test session on a test server that is already running at capacity or is otherwise unable to accept a test session. See Running a Test Session for more information on handling these types of errors.
Select the Reports tab when it becomes available. Ideally, your tunnel and MN session are established and the L2TP Tunnels Establish, Sessions Established, Attempted Session Connects, and Actual Session Connects measurements on the Test Summary tab are all 1. Explore the measurements displayed on the tabs. The measurement definitions are located in the Measurement Reference. Stop the test session when you are ready to continue.
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TROUBLESHOOT: If the L2TP tunnel is not established, first check the L2TP Node report tab and make sure that Total Received Packets is greater than 0. If not, either requests from the LAC node are not reaching the LNS SUT or responses from the LNS are not reaching the test server. Confirm that the SUT address is correct and ensure that there is connectivity between the LAC and the LNS. If L2TP Node shows that packets are being received, check the tunnel measurements on the L2TP tab for errors returned by the LNS. If the tunnel is established but the MN session fails to connect, look for Session Failures and accompanying session errors on the L2TP tab. If no specific L2TPerrors are reported, look for errors on the PPP tab. |
Next, increase the MN sessions and the test rates. Edit the test case... and set the Number of Sessions to 100 and the Activation Rate and Deactivation Rate to 10.
OK the change, and Run the test session again. This time you should be able to see the MN sessions establish over 10 seconds (10 sessions each second) after the tunnel is established.
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TROUBLESHOOT: If all of the MN session fail to establish, Attempted Session Connects will be larger than Actual Session Connects and Sessions Established. The most likely reason is a problem with parameter values that increment for each MN session:
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Finally, customize the optional behaviors to tailor the test to your purpose.
General options:
You can apply a distribution model to vary the activation and deactivation rates with Interval Distribution on the Mobile Node sub-tab. Click the Advanced Settings... button and the Interval Distribution dialogs opens.
You can introduce errors in the LAC node using the Advanced... options on the LAC Node Group sub-tab.
L2TP options:
PPP options:
Error Inject... (with asynchronous PPP)
After you have finished the definition and successfully tested it, save the test case and the test session as "LNS Base" or something similar.
Continue building your standard tests by adding L2TP IPSec, or expand your base test with other test activities or Data Traffic.