Software tests network software
Engineers at Adtran, a maker of DSL equipment, must test new features in the company's system-management software while making sure the existing features still work.
Martin Rowe, Senior Technical Editor -- Test & Measurement World, 9/1/2006 2:00:00 AM
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PROJECT PROFILE: Adtran
DEVICE UNDER TEST
Software that telecom carriers use to manage access networks and configure and provision services such as DSL for subscribers. It includes a GUI that provides an alternative to the Telnet interface when users need to access the DSLAMs. Using a client-server architecture, the software runs on a server that communicates to DSLAMs using Simple Network Management Protocol (SNMP).
THE CHALLENGE
Test the software by simulating both operator actions and a network of DSLAMs. Develop and run test scripts for automated interoperability testing. Provide pass/fail results in less than 24 hr.
THE TOOLS
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Adtran: DSL access multiplexers. www.adtran.com.
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Gambit Communications: Agent simulation software. www.gambitcomm.com.
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Mercury Interactive: TestDirector test-management software; QuickTest Professional (QTP) test-automation software. www.mercury.com.
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Shunra: LAN/WAN network-emulation software. www.shunra.com.
PROJECT DESCRIPTION
Adtran (Huntsville, AL, www.adtran.com) manufactures network-access equipment such as digital subscriber loop access multiplexers (DSLAMs) used by both carrier and enterprise business customers. The company also provides Element Management Software (EMS) that telecom carriers use to manage, activate, upgrade, and troubleshoot DSL services for subscribers.
The software runs on a Solaris or Windows server. It manages the DSLAMs using simple network-management protocol, and it provides a user interface to set and retrieve DSLAM configuration parameters. Telecom carriers use EMS to manage DSLAMs over geographic areas that can cover several states. Users at the carriers1397969521 offices communicate to the EMS server using client Windows or Solaris-based software through a wide area network (WAN).
Product qualification engineer Mike Barfield performs interoperability tests on the EMS. When the company adds new features, Barfield verifies interoperability between Adtran’s access products and EMS. Each new EMS release adds features that Barfield tests manually. He also verifies that existing features still work. Rather than test previously existing features manually, Barfield develops automated tests using QTP, called “regression tests.”
Regression tests check previously released functionality on a simulated carrier’s access network. “A customer may have as many as 6000 network elements or more,” he said. “A high-density DSLAM can service as many as 1344 subscribers, while a mini-DSLAM, used in remote areas, may serve up to 48 subscribers.”
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| Test-management software organizes and executes automated and manual tests. |
Barfield simulates user interactions by applying parameters and checking input boxes to previously existing features. To automate the user actions and to send commands to the DSLAMs, Barfield creates scripts for the EMS clients. He tests an EMS server with several thousand simulated DSLAMs before running new feature and regression tests. The software generates the EMS load by creating a large database on the server, sending alarm traps, and allowing device discoveries (figure). The functional and agent simulation software identify issues that occur on a stressed server.
Barfield uses TestDirector, which functions as a test executive, to select and run the tests. For example, one test case might check DSLAM parameters in the EMS by sending commands and checking the actual responses against expected responses. Checkpoints in the test script provide pass/fail results. If a failure occurs, the test software will capture a screen showing the failure, report the actual versus the expected results, and log the results.
LESSONS LEARNED
“Automation pays off,” said Barfield. “It saves considerable time in testing and retesting your product.” He can run several hundred test cases over a 24-hr period. He recommends that you plan sufficient time for updating your tests at the beginning of a test cycle: Identify manual tests that you can automate, remember that not all tests are suitable for automation, focus on the test objective and add checkpoints so you can verify the actual and expected results, and organize your test plan so it is easy to manage.
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