Reducing test costs through automated fiber switching

Feb. 6, 2006
By Michael McLaughlin, Glimmerglass -- The most time-consuming elements of test processes involve manually re-cabling fiber connections between devices under test and various test equipment. Engineers now can use all-optical switches to "refiber" these connections instantly and automatically, saving both time and effort.
IP traffic generators are connected to switching equipment that aggregates traffic to devices under test (DUTs). The optical switch reconfigures the connections between equipment interfaces and DUTs.

The most time-consuming elements of test processes involve manually re-cabling fiber connections between devices under test and various test equipment. Engineers now can use all-optical switches to "refiber" these connections instantly and automatically, saving both time and effort.

By Michael McLaughlin

Many of the test labs responsible for the industry's most sophisticated network technology still rely on manual test processes, even though huge efficiencies may be gained through test automation using optical fiber switches. Optical switch-enabled test processes allow new products to be tested in a variety of network configurations before they are released and shipped to customers. Furthermore, automated test processes enable engineers to save test scripts and configurations and repeatedly "reset" test conditions to reduce the time and cost of regression testing. Just ask Sandvine, provider of broadband networking solutions.

Sandvine's products enable Internet service providers (ISPs) to improve their subscribers' Internet experience. Sandvine solutions perform deep-packet inspections of Internet Protocol (IP) packets flowing through the Internet to identify the applications utilizing the ISP's network resources. These inspections occur in real-time, supporting Gigabit Ethernet (GbE) and 10-GbE data flows. Identifying applications enables the ISP to improve the way its resources are used. For example, the ISP can prioritize the connectivity for voice-over-IP (VoIP) packets ahead of a file backup task. Sandvine's products also filter out malicious or unwanted traffic.

Beyond the need to constantly adapt to new Internet threats, Sandvine faces other challenges, including a global, fast-growing customer base and the need to aggressively test the high volume of code generated daily. In addition, Sandvine has made a commitment to maintaining excellent product quality and a high level of customer satisfaction. These factors drove Sandvine's chief operating officer and vice president of engineering Brad Siim to implement test automation from the start.

"I knew that the testing lab was a great place to gain efficiency based on my previous startup experience," notes Siim. "With manual testing you can't reproduce problems as readily and the breadth of test-case coverage isn't as high. With more automation, you can focus your QA [quality assurance] team on making a difference, versus manual re-cabling to run nightly tests."

Despite its startup status, Sandvine chose to make a significant investment in its testing lab. "I wasn't interested in test lab cost savings; I was interested in maintaining an exceptional level of product quality," says Siim. "To do that, I needed a lab that could scale, execute at high speeds, and amortize expensive equipment as effectively as possible. We'll always have more engineers generating code than equipment to test it; it's the nature of the business."

The Sandvine lab consists of 500 load generators connected by edge switches, using copper GbE connections to Layer 2 and Layer 3 switching and routing equipment. The traffic is fed to 10-GbE core switches from Cisco and Foundry Networks. These switches aggregate the many GbE traffic flows from the load generators and the edge switches to 10-GbE interfaces over singlemode fiber. Sandvine needed to automate its method for passively connecting these "pipes" at the physical layer to its products under test.

"We didn't want to hardwire our boxes together," recalls Siim. "And in some cases we wanted to go directly between boxes without the potential interference of an agent in between them."

Sandvine selected the Glimmerglass Intelligent Optical Switch to enable its test team to automate the making and breaking of physical connections between the Layer 2 and 3 switches and its products under test, changing the connections on a test-case basis (See Figure 1). As a result, Sandvine can test more cases faster while using fewer of its products in the testing process. The company has improved product quality and engineering productivity--and saved money in the process.

Sandvine performs design verification during the day and regression testing at night, pushing mixed traffic and applications through its products to test features, functions, quality, and stability. To do this, Sandvine engineers created custom test automation scripts using the Tool Command Language (TCL). These scripts execute more than 20,000 test cases each night, re-configuring the lab as many as 1,000 times in a single day. Each test script agent calls the configuration manager to configure the equipment associated with the test case, controlling the load generators, devices under test, and the Intelligent Optical Switch.

"We need to find and fix software bugs on the same day they are written," says Siim. "You don't want to be in the penalty box with customers based on buggy software. We're continually beating up our products to make sure that doesn't happen."

The Intelligent Optical Switch facilitates this volume of testing. The transparent nature of the switch enables it to provide connections without further IP-level processing or delays; the connections truly are at layer 1 even though they are switched dynamically between tests by Sandvine's automated scripts (See Figure 2). In addition, the switch can handle any protocol or standard without change. The re-configurations are possible without manual intervention-- irrespective of data flow--and are performed around the clock, ensuring exceptional speed and scalability.

The cost and complexity of testing will continue to accelerate as the services, standards, and protocols on the Internet become more diverse. Sandvine's commitment to product test automation has enabled its engineers to scale quickly, handle immediate requirements, and anticipate a move to supply solutions for new standards--even beyond 10 GbE.

Companies like Sandvine must shorten their development schedules while simultaneously maintaining and even improving the quality of their offerings. Optical switches and an engineering team's commitment to test automation deliver compelling competitive advantages and therefore have become an emerging requirement for intelligent product engineering teams and their test labs.

Michael McLaughlin is vice president, corporate development for Glimmerglass (Hayward, CA). He may be reached via the company's Web site at
A small switching element uses micro-mirrors on a silicon chip and a built-in fiber patch panel to enable users to connect fibers and control physical-layer connections via a computer.