Layer4 to Layer 7 Web switches are proving their worth in e-business implementations.

By April Jacobs
Network World, 09/11/00

Is anyone surprised the Web has spawned development of its own kind of switch?

Layer 3 switches, fine for basic connectivity and packet routing, don't cut it in the Internet world, where traffic loads and application requests are all over the board. IT managers need the flexibility to treat different requests in special ways, and they're turning increasingly to these newfangled Layer 4 to Layer 7 switches.

Cahners In-Stat Group, a market research firm in Scottsdale, Ariz., reports that the worldwide Layer 4 to Layer 7 packet switch market reached $154 million in end-use revenue in the first quarter of this year. In-Stat expects the overall switch router market to reach more than 11 million ports shipped, 200% greater than the 1999 figure, and $5.5 billion in end-use revenue by year-end.

These switches - made by vendors such as Alteon WebSystems, recently bought by Nortel Networks for $7.8 billion in stock, and Top Layer Networks, one of Network World's 10 start-ups to watch in 2000 - perform Layer 4 through 7 functions. They look inside packets and then make forwarding decisions.

Layer 4 switching, or transport routing, lets IT managers implement policies based on traffic type and balance server loads. Layer 7 switches handle more complex tasks, such as routing a request based on who originates it and the type of content requested. Layer 5 offers session processing and application intelligence; Layer 6 brings in content presentation.

Advanced Web switches, such as the ArrowPoint products Cisco acquired earlier this year, rely on delayed binding. This technique lets a Web session involve two TCP connections - one that occurs between a client and the switch, the other between the switch and the Web server - after determining the request type. Otherwise, a switch would merely forward a request to a Web server based on availability.

These switches are not one-size-fits-all devices, so IT managers are advised to get a good handle on what they need to do before picking one. Some are for solo use, while others can work in conjunction with caching servers and other devices meant to help boost site performance, for example.

VeriSign, an Internet trust services provider in Mountain View, Calif., has identified a strategic need for Web switches capable of offloading customer download requests to specialized devices that handle Secure Sockets Layer (SSL) processing. The goal is to reduce the massive amount of processing Web servers otherwise have to handle each time a customer asks for a certificate, says John Ferguson, a director at VeriSign.

"There are a lot of folks who use these switches for personalization, but our whole business is hundreds of thousands of people who download certificates, so we do a tremendous amount of SSL traffic," he says. "When we are dealing with the volume increases we see, the answer is offload technologies. Now we can look to serve existing needs, plus offer additional services [such as payments]," Ferguson says.

At the bottom line is more efficient Web server use, increased reliability and faster response times. These are critical factors indeed, considering common statistics showing that more than a 6-second wait can mean a lost customer.

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