SANs See Sonet

Networking heavyweights Nortel Networks Corp. (NYSE/Toronto: NT) and Cisco Systems Inc. (Nasdaq: CSCO) are planning to roll out Fibre-Channel-over-Sonet extensions to their product lines this year, promising to give the emerging segment another big push forward.

Nortel, which has dominated the storage-over-WDM (wavelength-division multiplexing) market, is planning to provide FC-over-Sonet support for its OPTera Metro 5000 platforms sometime in the second quarter of 2003.

Most enterprises have several smaller, remote sites with SANs, but they don't want or need high-bandwidth WDM, says Jack Hunt, director of marketing in Nortel's optical storage connectivity division. "We're interested in enabling a lower-bandwidth storage-over-optical service," he says, "and we think Sonet is the best way to enable that."

Meanwhile, Cisco's on the storage-over-Sonet path, too, but it isn't revealing its plans in this area just yet. "You'll see storage over Sonet, at the OC3 and OC12 layers," says Carl Engineer, senior director of marketing for Cisco's optical networking group.

Cisco is developing FC-over-Sonet as a standalone system or as blades for its existing optical platforms. "Different solutions will be required by different customers," Engineer says. "For our installed base, a blade will be a good solution; if you're a smaller customer, a standalone box will be better."Engineer won't say whether Cisco is currently developing Sonet capabilities for its Fibre Channel switches and directors from Andiamo Systems Inc. But he does say the optical networking group has been working with Andiamo over the past year. "Customers need to take a look at their network evolution and realize that storage networking will be an integrated part of their solution."

The two powerhouse players will enter a space carved out by Akara Corp., which started selling FC-over-Sonet equipment two years ago, and startup LightSand Communications Corp. Lucent Technologies Inc.'s (NYSE: LU) OptiStar EdgeSwitch and Alcatel SA's (NYSE: ALA; Paris: CGEP:PA) 1696 Metro Span system also support FC over Sonet (see EMC OKs Lucent for SRDF, Akara Goes Wide , and LightSand Buffs Up Optical SANs).

Until recently, the primary way SANs have been extended synchronously at high speeds over metro areas has been via WDM. But while WDM provides very low latency and high bandwidth -- up to 10 Gbit/s per wavelength -- obtaining the dark fiber to run it is often difficult or impossible. Besides that, WDM is pretty much out of the price range of small and midsized businesses.

Sonet, by contrast, is ubiquitous, with an estimated 135,000 Sonet rings deployed in North America. "The ultimate driver for storage over Sonet is midrange enterprises implementing disaster-recovery solutions," says Steve Adolph, Akara's VP of product marketing. "Enterprises rule out WDM because they can't get dark fiber, or because it's too expensive."

Nortel's Hunt agrees: "We found that synchronous mirroring using DWDM is probably limited to the Fortune 500 companies that can afford their own private network."To date, though, FC-over-Sonet technology has received relatively limited uptake. Recently, Silicon Graphics Inc. (SGI) (NYSE: SGI) demonstrated its CXFS SAN file system sharing data at 8,000 km using LightSand's FC-to-Sonet gateway (SGI Elongates File System).

And there are still a few unknowns about the technology, says Cisco's Engineer: "Service providers aren't really up to speed yet on how to provision storage over Sonet, so it may end up in a finger-pointing scenario."

James Opfer, an analyst at Gartner Inc., sees FC-over-Sonet as an area ripe for takeoff, especially with the immaturity of IP-based storage networking technologies.

Moreover, he says that Sonet's tiered bandwidth options -- which can range from OC1 (51 Mbit/s) to OC192 (10 Gbit/s) -- mean companies aren't forced to overprovision. For example, even if an enterprise were running a 2-Gbit/s Fibre Channel SAN, it might not actually need an OC48 (2.5 Gbit/s) if its disk mirroring application wouldn't fully utilize that link. "The wide range of performance available and the matching wide range of costs [for Sonet] become the critical parameters in the planning process," Opfer says.

Todd Spangler, US Editor, Byte and SwitchTo view an archive of Byte and Switch's Webinar, "Storage Over Optical Networks: What's Driving Bandwidth," which was broadcast live on Feb. 5, click here