Extreme Networks is the latest company to launch an Ethernet switching fabric, saying that a flatter architecture is needed if enterprises are to take full advantage of cloud computing and virtualization. Like competitors Brocade, Force10, and HP, Extreme is pushing what it said is the openness of its architecture, that its fabric switches can interoperate with those of competitors and take advantage of a customer's installed base of switches.

So what makes Extreme different from its competitors? At Interop 2011 in Las Vegas, a UBM TechWeb event, the company was touting its high capacity, along with simplified management and a unified architecture from the data center to the mobile network. It launched two new switches at Interop: the 20-Tbps BlackDiamond X8 core switch and the Summit X670 Top-of-Rack switch. A 14.5 RU chassis with slots for eight cards, the BlackDiamond X8 supports up to 192 40-Gbps Ethernet ports or 768 10-Gbps Ethernet ports. Internally, its architecture directly links I/O cards to the backplane with no mid-tier.

The Summit X670G Top-of-Rack switch features 64 10-Gbps Ethernet ports, with 16 of them optionally replaced by four 40-Gbps Ethernet ports. Each switch supports up to 128,000 virtual machines, managed through Extreme OS Network Visualization (XNV) software. "You can literally drag and drop VMs around the network," Shehzad Merchant, senior director of strategy at Extreme, said in an interview.

Despite Extreme's emphasis on speed, support for 100-Gbps Ethernet is notably absent from its announced fabric products. According to Merchant, this is due to cost per Gbps. "A 100 gig is not 2.5 times the price of 40 gig; it's 10 times the price of 40 gig," he said. Even with the slight added complexity of managing more cables and switch ports, it's still cheaper to run multiple 40-Gbps Ethernet ports.

When the two new switches are clustered together into a fabric, a single-tier architecture can support up to 4,608 physical servers, a two-tier one up to 9,000, with each connected to the switch by 10-Gbps Ethernet. Three of the BlackDiamond X8s can fit into a rack, a feature that Extreme says is ideal for high-density environments.

Although Extreme and its competitors are talking about openness and interoperability, fabrics built using more than one vendor's switches are rare. "You can do that, but we're not seeing it in practice," said Merchant. This is partly because each vendor's gear is still built to work best with other switches and management software from the same company, partly because fabrics are so new.

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