We all know grocery shopping on an empty stomach and without a list in hand is dangerous if you expect to satisfy more than your immediate cravings. Likewise, shopping for network acceleration gear requires a clear understanding of current requirements as well as future expectations if you want to make a wise decision.

To lend a hand, Network World last week published results of a seven-month test of WAN acceleration gear. I read the review by David Newman, president of Network Test in West Lake Village, Calif., and was reminded, once again, of the importance of knowing what it is you need before making a purchasing decision.

While one product was named winner of our Clear Choice award -- Riverbed Technology’s Steelhead appliances -- for its top performance and reporting features, Newman singled out a number of products for excelling in particular areas.

For example, Blue Coat Systems’ SG appliances delivered solid HTTP and SSL optimization, while Cisco's Wide Area Application System (WAAS) provided excellent compression, traffic transparency and interoperability with other devices, according to Newman. Silver Peak Systems’ NX appliances, meanwhile, stood out for strong scalability and intuitive traffic reporting tools. “…all these devices deserve serious consideration,” Newman said.

To decide which appliance could be a fit for your company, start by considering what’s most important in your network setting. The ability to speed bulk transfers might be critical if you’re conducting backups and disaster recovery processes over the WAN. Or, improving response time for revenue-generating applications might be a key priority.

And don’t forget about interoperability. Acceleration devices need to coexist with firewalls, bandwidth mangers and routers performing QoS -- which may need to examine traffic contents. If an acceleration device alters or hides packet contents in order to speed up delivery, it can hamper other traffic-inspecting gear. Newman’s advice? “Grill vendors on whether or not their products will ‘blind’ other devices, such as firewalls or bandwidth mangers, that need to see packet contents,” he said.

In a podcast interview with Network World’s Keith Shaw, Newman also offered some advice for enterprises that want to test WAN acceleration gear on their own. It’s no easy feat -- it took Newman and his team a great deal of effort to create an enterprise-caliber test bed representing a multiple-site WAN. (He explains the process in the podcast.)

Ann Bednarz is associate news editor at Network World.