When Nanometrics bought Accent Optical Technologies, it faced a tricky problem: balancing WAN optimization on the one hand and VoIP quality on the other.

Accent Optical was involved already in an extensive and cost-saving VoIP deployment; and Nanometrics, a maker of measuring tools for semiconductors, was testing WAN optimization gear to improve intercontinental WAN performance and save money as well. The two technologies weren’t playing well together, however, says Dave Kizer, director of IT for Nanometrics.

The problem was that the Riverbed Technology WAN optimization gear being tried out didn’t observe the QoS tags on VoIP packets, subjecting VoIP to unacceptable delays when the Riverbed appliances were taxed by large file transfers, Kizer says. “They slowed down the VoIP, and voice quality is Number One.”

So, he shopped around for an alternative and ultimately chose Cisco, which is his VoIP vendor as well. He says the price was competitive, the gear used the Cisco command-line interface his staff was familiar with, and the optimization gateways were blades that fit in the company’s Cisco Integrated Services Routers, eliminating yet another chassis in the equipment room.

The main reason he chose Cisco, however, was the integration between the Wide-Area Application Services (WAAS) modules and the router, Kizer says. When the router tags the VoIP traffic for priority, it can send the traffic on its way without it being queued up for the WAAS module, he says.

With the Riverbed gear, which sits inline with traffic -- meaning all traffic headed for the WAN had to pass through the box -- VoIP packets could pass through without being processed by the optimization software; but under heavy load, even waiting for pass-through caused enough delay to degrade voice quality, Kizer says.

WAN optimization is a priority for the company because it helps enable a major data-center consolidation project that will put its major corporate servers in a facility in San Jose, near Nanometrics' headquarters in Milpitas, Calif.

That consolidation will minimize investment in data-center infrastructure and the overhead of ongoing management and maintenance, he says.

Kizer recommends that companies considering a WAN optimization project also consider whether VoIP is in the picture. He urges trying out the gear with a sampling of network traffic to find any unexpected consequences of adding the optimization gear. Doing so for Nanometrics' project saved the cost of deploying, then ripping out 18 optimizers that would have been inappropriate for VoIP, he says.