LOS ANGELES -- OFC 2004 -- At OFC last year, component and module vendors spoke of a "fast track" for the XFP multisource agreement (MSA) for 10-Gbit/s links (see, duh, XFP Gets the Fast Track). But this year, the fast ramp leveled off.

The difference is Fibre Channel's newfound 4-Gbit/s generation. Most of the vendors hearing buzz for XFP were talking to storage networking customers who were anticipating the leap to 10-Gbit/s. Then, out of nowhere like Keisha Castle-Hughes's Oscar nomination, the Fibre Channel Industry Association (FCIA) voted to extend 4-Gbit/s Fibre Channel to storage area networks (see FC Fires Up 4-Gig Fiesta).

Suddenly, those 10-Gbit/s plans aren't so urgent. "Even the staunch supporters of 10-Gbit/s [for storage networking] have pushed it out," says Robin Crandall, senior vice president of sales for E2O Communications Inc.

XFP, which specifies a serial module for 10-Gbit/s Ethernet, has always been a next-generation play. The 300-pin MSA reigns for now, and it's being followed by the Xenpak and X2 modules, which split 10-Gbit/s signals into four lanes. XFP would come after that. (For further details, see 10-GigE Transponders: Update.)

The modules use different levels of technology. For instance, Xenpak was created for a quick rollout; Cisco Systems Inc. (Nasdaq: CSCO) is shipping Xenpak line cards now. But SAN vendors weren't planning on immediate 10-Gbit/s Fibre Channel shipments, nor do they have a 10-Gbit/s installed base to worry about. This combination gave them the luxury of considering a leap to XFP.

The emergence of 4-Gbit/s creates a less certain future for XFP modules -- and 10-Gbit/s gear generally -- in storage networking. XFP will still get play there, as companies such as Brocade Communications Systems Inc. (Nasdaq: BRCD) are continuing development of 10-Gbit/s switches, but those switches might never become mainstream.

"We didn't delay our technology, but our expectation is that 10-Gbit/s [Fibre Channel] is going to be more of a niche product," says Jay Kidd, chief technology officer of Brocade's infrastructure group.

In fact, there's talk that the next step for SANs won't be 10 Gbit/s, but 8 Gbit/s. In that case, SAN vendors might use 10-Gbit/s modules and run them at slower speed, but that's not a sure thing. "That's one of the things the standards guys are looking at," Kidd says. "There are some fundamental differences between 10 Gbit/s and 4 Gbit/s regarding how the bits are encoded on the wire."

So XFP loses what might have been a head start on revenues, but the business proposition remains intact. "The storage guys don't drive the volumes. The Ethernet guys will," says Ed Cornejo, director of applications marketing for Opnext Inc.

Meanwhile XFP and the other "X" modules showed progress at OFC. Bookham Technology plc (Nasdaq: BKHM; London: BHM) demonstrated an early version of an 80-kilometer XFP device, and Finisar Corp. (Nasdaq: FNSR) showed an 80km DWDM XFP module (see Finisar Gets XFP Happy). Most other vendors say they're concentrating on the 10km and 40km XFP versions first.

Other vendors in the XFP game include Agilent Technologies Inc. (NYSE: A), Avanex Corp. (Nasdaq: AVNX), Infineon Technologies AG (NYSE/Frankfurt: IFX), Intel Corp. (Nasdaq: INTC), JDS Uniphase Corp. (Nasdaq: JDSU; Toronto: JDU), LuminentOIC Inc., MergeOptics GmbH, Network Elements Inc., Picolight Inc., Sumitomo Electric Industries Ltd., and TriQuint Semiconductor Inc. (Nasdaq: TQNT).

— Craig Matsumoto, Senior Editor, Light Reading

For more information, see the Light Reading Webinar, 10-Gig Ethernet Transponders: Latest Developments