Report Looks Beyond 4-Gig

As 4-Gbit/s Fibre Channel settles in for SAN adoption, a debate is already brewing over the next jump in speed, according to the latest report from Byte and Switch Insider, this publication's paid subscription research service.

The logical upgrade path from 4 Gbit/s is 8 Gbit/s, but some industry players make the case for a direct leap to 10-Gbit/s Fibre Channel, skipping 8 Gbit/s altogether.

According to the report, "4-Gbit/s Fibre Channel: The First Step Toward the Future," a migration from 2-Gbit/s and 4-Gbit/s infrastructures to 8-Gbit/s would have the advantage of backward-compatibility. That feature helped it get a recent endorsement by the Fibre Channel Industry Association (FCIA), which this week announced an extension of its fabric standard to include 8-Gig FC on optical connections. (See FCIA OKs 8-Gig Standard.) Previously, many thought 8-Gbit/s FC would merely be a copper-based method of cabling together different SAN devices at some point in the future.

Meanwhile, 10-Gbit/s FC has been available as an interswitch link (ISL) for FC SANs from some of the same vendors that also applaud 8-Gbit/s, most notably QLogic Corp. (Nasdaq: QLGC). Others that pledge support for both 8- and 10-Gbit/s include Emulex Corp. (NYSE: ELX) and LSI Logic Corp. (NYSE: LSI). These vendors' strategies are outlined in detail in the report.

As SANs grow in size and complexity, ISLs will be vital links in the SAN chain, and greater speeds will be required not only to handle more segments but to mitigate port loss between switches resulting from redundant links.Proponents also say 10-Gbit/s will be more compatible with enterprise networks because it shares a physical layer with Ethernet. Savings in R&D and components, however, could be canceled out by the cost of a forklift upgrade for HBAs and storage gear, which a 10-Gbit/s fabric would require.

Can the industry support a move to both 8- and 10-Gbit/s fabrics?

Suppliers would like us to think so, even though a lot of what's talked about now may not actually materialize. Twenty-five vendors, listed in the report, have announced 4-Gbit/s products and say they'll ship within the next few months. Yet of all the announcees, just a few are actually shipping wares -- including Emulex, LSI Logic, and QLogic.

Ultimately, the report concludes, 4-Gbit/s FC, which almost didn't make it, is opening the way to future iterations of the protocol. And nothing's written in stone: Eventually, we're likely to see a mixture of SAN speeds working together in future networks, with quality of service (QOS) implemented as it is in the IP world.

In the meantime, look for trends by which to gauge the race between 8- and 10-Gbit/s. The big question will be how important a role Fibre Channel will take in SANs of the future. A leaning toward FC could spell good times for 8-Gig, whereas Ethernet and IP considerations could make 10-Gig the speed of choice.Brett Mendel, Senior Analyst, Byte and Switch Insider, and Mary Jander, Site Editor, Byte and Switch

More information about the current Byte and Switch Insider report, "4-Gbit/s Fibre Channel: The First Step Toward the Future," is available here