10G or not 10G?

That is the question regarding high-speed switch products.

If you're looking to add 10 Gigabit Ethernet to your corporate backbone, you might want to wait for the next generation of switches from vendors such as Cisco, Extreme Networks and Foundry Networks to ensure you're getting the most bang for your buck.

That's because most existing Ethernet boxes have a kink: they really only deliver 8G bit/sec. Vendors will make up for that speed with next-generation chassis upgrades - which could come as early as next year.

Although some currently offer 10G Ethernet modules, "most vendors are using switch chassis that were designed three or four years ago to support Gigabit Ethernet," says David Newman, president of Network Test, an independent network equipment test lab and a member of Network World's Global Test Alliance.

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If you're looking to add 10 Gigabit Ethernet to your corporate backbone, you might want to wait for the next generation of switches from vendors such as Cisco, Extreme Networks and Foundry Networks to ensure you're getting the most bang for your buck.

That's because most existing Ethernet boxes have a kink: they really only deliver 8G bit/sec. Vendors will make up for that speed with next-generation chassis upgrades - which could come as early as next year.

Although some currently offer 10G Ethernet modules, "most vendors are using switch chassis that were designed three or four years ago to support Gigabit Ethernet," says David Newman, president of Network Test, an independent network equipment test lab and a member of Network World's Global Test Alliance.

"Different boxes are designed in different ways . . . but the most bandwidth many of these products can offer is 8G bit/sec of capacity" at best, he says. Newman adds that this limitation is because most chassis were designed with 8G bit/sec interfaces between module slots and the chassis' switching fabric.

Another industry watcher says even 8G bit/sec is generous. Bad implementations of features such as flow control, which regulates the flow of high-speed packet streams to a port, can cause throughput to dip below 7G bit/sec on some products, according to Brian Tolly, senior engineer and analyst with Tolly Group, a network testing and consulting firm.

Price isn't right

"For the price that 10 Gigabit is going for," says Sheng Guo, CTO for the State of New York Unified Court System, "I would want to make sure support for 10 Gigabit Ethernet really means I'm going to get 10 gigabits per second."

Guo's network connects court and correctional facilities throughout New York over dark fiber and a mix of metropolitan-area Gigabit Ethernet and SONET. Guo says that he's found 10G Ethernet to be cost-prohibitive. And the idea that the technology might not deliver as much bandwidth as it promises makes him inclined to put off any tests until vendors can support the real thing.

The main reason most boxes don't really support the higher speeds is that switch platforms such as the Cisco's Catalyst 6500, Foundry's BigIron 15000, Extreme's BlackDiamond 6800 and Nortel's Passport 8600 have all been on the market for years. The 10G Ethernet standard was only ratified by the IEEE this summer.

The limitations of these chassis for handling 10G Ethernet are widely known, vendors claim.

"We have 8G bit/sec to each slot on our chassis," says John Erlandson, director of product marketing for Extreme. "That's well-documented, and we've never tried to disguise that in any way."

In addition to providing full-duplex 8G bit/sec, Erlandson adds, Extreme's products also can handle features such as quality of service and multilayer routing without affecting throughput.

"The performance our customers are getting now, at 8 gigabits per second on one pipe, is eight times as fast as Gigabit Ethernet, and almost as fast as SONET OC-192," which is about 9.9G bit/sec. However, he adds, the cost for 10G Ethernet is about a quarter the price of its virtual SONET equivalent.