The 'Human' Side of Network Testing

A San Francisco-based software vendor says it has the answer to a key problem facing carriers and equipment makers: namely, predicting how consumer access networks will run when live user traffic is added.

The company, interNetwork Inc., has developed the means to generate end-user traffic in software, creating a flow to stress-test devices like routers, DSLAMs, switches, and other gear in conditions that duplicate those of live broadband networks.

Its product, dubbed smartTest, runs under Linux or Solaris on run-of-the-mill PCs or workstations. With a new release announced today, it offers a GUI for creating made-to-order traffic, which is sent to devices linked to the workstations as they'd be in a live network.

"We're generating thousands of real users, not emulating or packet blasting," says Dharmesh Thakker, interNetwork senior product manager.

Between 8,000 and 12,000 users can be created per workstation, he says, and a separate machine typically acts as the server. Results are automatically gathered for analysis via the same GUI that's used to set things up.

It's not a new proposition: Test vendors Ixia (Nasdaq: XXIA) and Spirent Communications also offer software that duplicates end-user traffic. But interNetwork says it goes further than these vendors toward mimicking real-world conditions at one go. What's more, interNetwork's product is software only, so it doesn't call for special tester platforms. That saves at least a third on up-front costs, the vendor claims.

For instance, SmartTest establishes a multilayer protocol stream that includes data link point-to-point protocol (PPP) setups. This is essential, interNetwork says, for accurately testing a range of access services, such as ATM, DSL, or cable modem offerings, which use PPP as the data link to upper-layer IP protocols.

On top of these underlying protocols, SmartTest adds a full range of upper-layer traffic, mimicking user authentication transactions with application content, including HTTP, FTP, MP3 music, and video streams.

The result is "stateful" traffic, in which encapsulated packets with user payloads subject equipment to the same stresses they'll encounter in live nets.

It's a contrast -- or complement -- to using multiple programs running on dedicated hardware testers, which is the approach taken by Ixia and Spirent. "We provide an intersection of Layer 2 through 7 protocols. Others offer a union," says Thakker.

Still, tester vendors have long pooh-poohed the use of software-only products for stress testing, claiming they can't offer the scaleability of dedicated hardware. Spirent's PPPox Emulation Test Suite, for instance, which runs on the vendor's hardware, can duplicate the impact of 256,000 subscribers per chassis, Spirent claims -- considerably more than what SmartTest can furnish per PC. Earlier this month, Spirent boasted of its ability to hammer lots of sessions at Cisco Systems Inc. (Nasdaq: CSCO) gear (see Cisco 10000 Passes Spirent Test).

At least one expert says there's another possible drawback: Using end-user traffic to stress-test networks doesn't necessarily provide an answer to problems that arise. "The issue with real world mixes... is that it becomes very difficult to pin down the root cause of a performance anomaly," writes Bob Mandeville, president of Iometrix Inc. and Light Reading's Ethernet Project Director. Speaking hypothetically, the end results may be the same as those of a hardware-based unit that tests one factor at a time, he says, but troubleshooting could be tougher.

None of this bothers interNetwork. There will always be room for software testing alongside hardware approaches, Thakker says. SmartTest has over 16 customers worldwide, including Bell Canada (NYSE/Toronto: BCE), Deutsche Telekom AG (NYSE: DT), and Nortel Networks Corp. (NYSE/Toronto: NT), who have used interNetwork's product as a capacity planning and predictive analysis tool, the vendor says. What's more, these customers glommed on when the product had a command-line interface. With the new GUI and automation added, interNetwork's convinced it's got a hot-ticket test item.

InterNetwork was founded in 1999 by Till Immanuel Patzschke, a technologist who spent 16 years as CEO of a European test software company. It's funded by German VCs Target Partners GmbH and Earlybird, but amounts haven't been disclosed.

— Mary Jander, Senior Editor, Light Reading

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