XFP Gets the Fast Track

Vendors at OFC say the 10-Gbit/s transceiver standard is advancing quicker than expected

March 25, 2003

5 Min Read
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ATLANTA -- OFC 2003 -- Futuristic technologies like 40-Gbit/s OC768 may be out of favor, but at least one next-generation technology could be a hit at the OFC Conference this week: XFP modules for 10-Gbit/s transceivers.

Finisar Corp. (Nasdaq: FNSR) and Ignis Optics are among the module vendors demonstrating XFP at the show, and larger companies such as Infineon Technologies AG (NYSE/Frankfurt: IFX) and Intel Corp. (Nasdaq: INTC) have made recent XFP announcements as well (see Infineon Intros XFP Modules, Others and Intel Launches Five GigE Products).

Sure, part of what's going on is the usual tradeshow hype. But there's also a feeling that XFP is gaining quicker acceptance than even the module vendors expected. "Even very traditional telecom OEMs [original equipment manufacturers] are starting to implement XFP in next-generation products," says Christian Urricariet, director of marketing for Finisar.

Quick review: XFP is a multisource agreement (MSA) that dictates size, shape, and interfaces for a transceiver module (see XFP Unveils Spec). It's the latest in a succession of MSAs for 10-Gbit/s:

  • The 300-pin MSA is the reigning champ, claiming most of the shipments today. It converts between a 10-Gbit/s optical signal and sixteen 622-Mbit/s electrical signals.

  • Xenpak is the first improvement on the 300-pin MSA, using four 3.125-Gbit/s channels on the electrical side. OEMs wanting to launch products immediately are going with Xenpak, and Intel officials say we should see Xenpak-packed switches announced next quarter.

  • But Xenpak was a rush job and is larger than desired, so the XPAK and X2 MSAs are dueling it out as the next step for these modules (see Is Xenpak Past It? and The X-Wars: Agilent Strikes First). These each use four lanes of 3.125 Gbit/s.

  • XFP is an MSA for a 10-Gbit/s serial module. Being serial, XFP presents a more compact module, at just 30 pins. But it adds the complexity of running 10-Gbit/s signals into neighboring chips, something that can't quite be done yet.

XFP was intended for the generation following XPAK or X2. But some OEMs are beginning to consider moving directly to XFP.

Even some systems due to sample aren't locked into an MSA yet. "Some of them are already lined up. Some of them are trying to make their decision on form factor," says Bob Zona, senior product marketing manager for Intel's optical platform division. Things are even more open-ended in the storage networking area, which hasn't reached 10-Gbit/s speeds yet.

Once chips can handle 10-Gbit/s signals, XFP is expected to dominate over the other MSAs, because it's the most compact of them and eventually will be the cheapest as well. That factor is prompting some OEMs to investigate XFP a generation early, even though it currently requires an extra chip to convert the 10-Gbit/s serial feed into 3.125-Gbit/s lanes on the electrical side.

"People realize that, so you might as well start designing for it now," says Steve Joiner, Ignis director of marketing. "We have some people moving directly from 300-pin to XFP."Officials at Finisar are a bit more blunt about the Xenpak and XPAK/X2 steps: "We really believe they add no value," Urricariet says. "They're sort of interim solutions."

At OFC, both Ignis and Finisar are showing XFP modules transmitting over a distance of 40 kilometers. In telecom applications, that kind of distance usually calls for a 1550nm laser -- and Finisar plans to offer both 1310nm and 1550nm XFP modules, so it's got that area covered (see Finisar Demos XFP Transceiver ).

Ignis, though, offers only 1310nm parts, so vice president of marketing Steve Joiner considers his 40km demo to be a toe in the water. "There are some advantages," he contends, in using 1310 nm rather than 1550 nm. "I want to ask the market if that's worth any money."

Of course, the 1310nm market could still be lucrative for reaches of around 10 km. It's also got a future in storage networking, which is still awaiting the standardization of 10-Gbit/s Fibre channel. "The Fibre Channel companies were very strong in the early definition of XFP," says Claude Denton, vice president of marketing for Network Elements Inc.

On the electronics side, Applied Micro Circuits Corp. (AMCC) (Nasdaq: AMCC) and Broadcom Corp. (Nasdaq: BRCM) have each produced adapter cards that allow an XFP module to be plugged into the slot for a 300-pin MSA. The cards are intended for testing, so that OEMs can begin working with XFP without waiting for new boards to be completed. Both adapter cards will be on display at Ignis's OFC booth.More dramatically, BitBlitz Communications Inc. announced the BBTX400 chip, which contains all the electronics for four XFP connections. This kind of chip could pave the way for quad or octal XFP cards, which could emerge as early as this spring, according to CEO Ed Rodriguez.

The chip supports either Ethernet or Sonet and consumes 5.2 watts, compared with 1.5 watts apiece for single-lane XFP electronics, says Rodriguez.

Finally, Network Elements recently announced "micromodule" technology that eventually could shrink a transceiver down to the size of a chip. This device would even attach to a board the way a chip does, using ball-grid-array connectors, doing away with the sliders and rails used in transceiver MSAs. "You can remove every last bit of mechanical cost out of the package," says Claude Denton, vice president of marketing.

Network Elements plans to use the technology for a 12km XFP module, but that's still in development. At OFC, the company will show a 300-pin-MSA module built using micromodule technology to create a very thin and inexpensive package.

Even after micromodules, the transceiver could shrink further. "Solder-on optics will be the next thing after XFP, and that's still some way out," Denton says.Craig Matsumoto, Senior Editor, Light Reading

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