Businesses looking to make better use of expensive WAN links have a new option: a PC-based Linux appliance that compresses data traffic so businesses can send more over existing connections without having to buy bigger pipes.BURLINGTON, MASS. - Businesses looking to make better use of expensive WAN links have a new option: a PC-based\u00a0Linux appliance that compresses data traffic so businesses can send more over existing connections without having to buy bigger pipes.Eight-year-old\u00a0ITWorx\u00a0is introducing the device, called NetCelera, which the company says will use data compression techniques to cut the volume of traffic at least in half and by as much as 90%.Customers have to buy at least two of the devices and place one at each end of a WAN link between the router and the LAN. Like other compression vendors such as\u00a0Expand Networks\u00a0and\u00a0Peribit Networks, ITWorx's compression technology works by examining traffic for patterns that repeat, then replacing them with shorter patterns that it keeps track of in a library.NetCelera is different from competing products because it examines traffic at the session layer, Layer 5, says CEO Youssri Helmy. Layer 5 compression means the device can differentiate session streams within all the traffic on a wire, such as a file transfer vs. a client-server application. NetCelera then can develop a unique compression library, maximizing the compression for each session up to 8,000 sessions, he says. Other vendors' compression methods use a single library for all traffic on a particular physical connection.NetCelera doesn't try to compress video or voice-over-IP traffic because they are already compressed. Further attempts to compress them with NetCelera's current technology would yield minimal improvements that would not be worth the processing power, Helmy says. But he says the company is developing software for a later release that will compress voice enough to make the effort worthwhile.While its data compression technology might give it an advantage in the market, ITWorx has its work cut out for it, says John Cordova, an analyst with Infonetics. Competitors, such as Expand, Packeteer and Peribit, all offer another key feature along with compression: traffic shaping. This is significant because packet-shaping and compression gear occupy the same space in a network, and putting both functions in one box simplifies matters, he says. Similarly, vendors such as Array Networks are adding compression to their multiservice security platforms, and many router vendors now offer compression as an option on their gear."Maybe just being a compression box right now isn't enough," Cordova says. Within a few years compression and others of these features will be primarily sold as options on routers, he says, and customers will take that road rather than add another box to their networks. But he says compression can save companies from buying larger WAN connections, particularly expensive international lines, and that can pay for the equipment within months.NetCelera has two 10\/100M bit\/sec Ethernet ports that connect it to the router on one side and the LAN on the other. If the device fails, it passes traffic through untouched.NetCelera is priced depending on the size of the WAN link it supports. For example, a box for a 128K bit\/sec line costs $2,500 and one that supports a T-1 costs $8,000.