Data compression devices have been around for years, but in their latest incarnations they use more than just compression technology to pack extra data onto fixed-size WAN links as a way to boost performance and save money.

For example, International stock trading firm Forex.com uses a new device from Internap called FlowControl Xcellerator (FCX) to improve performance on the Internet link used to back up data from its Hong Kong office to the company's New York data center.

The New York site is connected to the Internet by a 400M bit/sec line, and the one in Hong Kong is connected by a 2M bit/sec line. But because of Internet latency between the two locations, says Brandon Palmer, Forex.com's IT director, "the throughput was 40K bit/sec at best. It took 16 hours to do backup."

With an FCX device at each site, performance is boosted to 320K bit/sec, he says, reducing back-up time to about two hours. While FCX boxes tinker with TCP to improve performance and don't use traditional compression, Palmer says he thinks about its function as compression anyway. By analyzing WAN performance, FCX boxes decide whether they can improve throughput by overriding TCP before it can throttle traffic or by restoring traffic to full speed faster than TCP would. If FCX algorithms produce faster response times for applications than TCP, then the devices step in.

"What I see appears the same as compression," he says. With the price of a pair of boxes for $20,000, the payback is about two years," he says.

Internap, while one of the most recent vendors of WAN optimizing gear, is far from the only one. Competitors include Expand Networks, FatPipe, NetScaler, Netli, Packeteer, Peribit, Riverbed and Swan Labs. Router vendors, many of which offer compression as a feature, can be added to the list.

All these vendors deploy their appliances in pairs at both ends of WAN connections. There they perform a variety of functions to squeeze more out of fixed links.

Approaching the problem

Many vendors come at the problem from different angles. Some, such as Expand, started out selling traditional compression - replacing patterns with smaller patterns so less traffic crosses the link. Others, like Orbital Data, use the fact that TCP throttles back traffic when faced with delay, then builds it back up to speed very slowly - more slowly than network conditions might warrant - when the perceived congestion clears. Others, such as Riverbed, look at applications and spoof predictable back and forth locally in the appliance rather than have the full conversation cross the WAN. Others shape traffic to give higher priority to key applications that are optimum WAN speeds.

And still others use more than one technique and claim effective throughput improvements of 90% or more depending on the type of data.

Peter Firstbrook, senior research analyst with Meta Group, says by making efficient use of expensive international lines, these devices provide near-immediate payback that attracts far-flung corporations as customers.

The promise of cost savings is prodding service providers such as TeleManagement Systems and Midwest Data Center to offer compression services based on these devices. These providers say they can save customers enough to make buying a managed service worthwhile and still leave a profit margin for the provider. For example, Midwest Data Center, a storage and hosting provider in Rock Port, Mo., says it charges $500 per month for compression using gear from Swan, which bases its appliances on technology it bought from ITWorx. "It provides 600% compression," says Rob Lee, Midwest's CTO. One customer would have faced buying 50M bit/sec more bandwidth for backing up its network to Midwest, he says, so the service saves it more than $13,000 per month.