Carrier Ethernet Tackles Storage

Carrier Ethernet is becoming a key transport for storage, sources say, though carriers and their suppliers offer uneven input on the trend.

Carrier Ethernet, also known as metro Ethernet, lets corporate customers link to remote sites and branches via 10-Mbit/s to 1-Gbit/s Ethernet links, usually within a metropolitan area. Storage traffic -- for business continuity, offsite replication, and remote backup applications -- can be shipped with other data, as long as customers can convert SAN protocols for use on the net.

Up to now, most carriers haven't seen a need to offer more than this, since they don't distinguish SAN payloads from other Ethernet-borne traffic.

In the "2006 Survey of Ethernet Service Providers," for instance, Heavy Reading senior analyst Stan Hubbard reported that among 50 Ethernet service providers surveyed, 24.3 percent offered storage extension (native SAN interfaces over Ethernet) among their applications, but 38.8 percent had no plans to add offerings in the future. Further, 44.2 percent of respondents believed there was "little or no" demand for Ethernet-based storage extension services at any data rate. (See Flirting With Storage Services.)

That seems to be changing, particularly as Ethernet services become more prevalent and users look to extend their investment in them. AT&T now offers FibreMAN, a 1- and 2-Gbit/s Fibre Channel service, as part of its metro Ethernet offerings in the 13 states formerly associated with SBC -- Arkansas, California, Connecticut, Indiana, Illinois, Kansas, Michigan, Missouri, Nevada, Ohio, Oklahoma, Texas, and Wisconsin.Elsewhere, Orange Business Services, a subsidiary of France Telecom, just announced i-SAN, a business continuity service that's part of its Orange MAN Ethernet services. While restricted to the Paris area, Orange says i-SAN, by virtue of being a turnkey service, will offer easy access to remote replication for firms of all sizes. (See Atrica, Orange Unveil iSAN.)

Other companies say they're gearing up for SAN-specific offerings. Optimum Lightpath, the Ethernet services arm of Cablevision, is planning a SAN service for small and mid-sized companies for release by the end of this year.

"I'd say probably 10 percent of our point-to-point circuits now connect to some kind of SAN or business continuity center," says Kevin Curran, SVP of marketing at Optimum Lightpath. Though the carrier now offers corporate customers redundant Ethernet circuits for business continuity, the SME offering would be a dedicated link for storage, something he says many companies are requiring these days.

Other sources confirm his view. "SAN extension is becoming one of the significant drivers of carrier Ethernet adoption," states Nan Chen, president of the Metro Ethernet Forum and VP of marketing at Strix Systems, which makes wireless Ethernet mesh networking gear.

"Business continuity, along with collaborative-type tools and global private networks, is one of the major application drivers for Ethernet service," says Keao Caindec, chief marketing officer at Ethernet provider Yipes Enterprise Services.This doesn't mean Ethernet service providers are running to market with SAN links, though. Like many service providers, Yipes doesn't offer native SAN connectivity in its portfolio. Instead, the company hooks its circuits into networks from Iron Mountain and other providers of digital online backup, replication, and business continuity services.

Likewise, makers of the switching equipment on which most Ethernet service providers base their services aren't focused on SAN interfaces. While some vendors like Nortel offer native SAN connectivity on their provisioning platforms, others, including Extreme Networks and Foundry, do not.

This doesn't mean they don't support SAN traffic. Like their service provider customers, the Ethernet switchmakers see SAN as yet another form of IP traffic. "We do not support any specific SAN interfaces such as Fibre Channel or iSCSI," writes Bill Ryan, product marketing manager for Foundry's high-value systems business unit, in an email. "We do transit SAN over Ethernet and are able to apply QoS profiles to such traffic giving it higher priority to lower jitter and latency for the traffic... In a straight L2 world, we will prioritize traffic based on the ethertype. In a routed environment, we are counting on the SAN traffic to be encapsulated with an IP header, in which case we can prioritize any packets with the SAN IP address as either source or destination."

Clearly, as customers increase their use of Ethernet services, it's likely they'll also focus on getting more SAN-specific offerings, particularly if they're shelling out money for separate SAN services like online backup on top of paying several thousand dollars per month for Ethernet circuits.

A lot has to do with a user's level of SAN traffic. Example: Tero Caamano, director of information technology at Saint Clare's Hospital in Morris County, N.J., says the 2-Gbit/s Ethernet link from Optimum Lightpath is fine for medical image backups involving an EMC Clariion CX700 in one location and a short-term medical records archive at a neighboring campus. SAN data is piped along with other traffic over the extended LAN.That's fine for now. But if the volume of medical images starts to interfere with regular traffic flows, Caamano says he'd look into a dedicated link. "We'd probably split SAN traffic off and get separate connectivity," he says. And at that point, a SAN-oriented Ethernet link might come in handy.

Mary Jander, Site Editor, Byte and Switch