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OFC participants eagerly await 25G chips

Posted: 11 Mar 2011 ?? ?Print Version ?Bookmark and Share

Keywords:100Gbit/s? Ethernet? 25G chips? CMOS? CFP modules?

Engineers promoting 100Gbit/s Ethernet are counting on chipmakers to bring parts supporting 25Gbit/s signaling in CMOS to the ongoing Optical Fiber Conference (OFC) in Los Angeles. OFC/NFOEC participants will also try to pursue new efforts in line with or even beyond the recently drafted 100Gbit/s Ethernet standard.

First-generation chips and systems for 100Gbit/s Ethernet are using ten lanes of 10Gbit/s channels. Engineers are driving toward more efficient next-generation products based on four 25Gb lanes, a speed that pushes the edge of CMOS design.

The arrival of 25G chips in CMOS "is a major industry trend that will become apparent at OFC with multiple industry announcements," said one senior optical engineer. "We have already seen FPGA suppliers last year [announce] 25G I/O, and Avago announcing recently 30Gbit/s CMOS serdes for their high-density switch ASICs," he added.

Hitachi showed at the International Solid State Circuits Conference a 65nm chip that could multiplex four 25G signals for 100Gbit/s Ethernet links while consuming just 2W.

So far, only a handful of announcements of 25G products have hit the wires this week, many of them focused on optical modules, not silicon.

Gennum announced two 25Gbit/s clock and data recovery ICs, the GN2425 and GN2426. What systems makers most need are serdes chips capable of driving 25G signals, but so far vendors such as NetLogic Microsystems are showing 10Gb serdes at OFC.

In terms of optical modules, Finisar announced what it claimed was the industry's first 4x 25G optical transceiver based on the specification of the CFP Multi-source Agreement. The prototype module is based upon four DFB lasers running at 25.8Gbit/s each and complies with the 100GBASE-LR4 (4 x 25Gbit/s) optical interface defined by the IEEE 802.3ba standard.

The company said the 4x25G module will dissipate 12W, significantly less than a first-generation 10x10G module and support lower costs.

Separately, Avago demonstrated a high-temperature 25Gbit/s, 850nm VCSEL integrated into an SFP+ optical module. It used Avago's 30Gbit/s serdes, made in a 28nm process, to run the 25G signals over 100m of OM3 multimode fiber.

Looking beyond 100G
The IEEE recently created a working group that will deliver a standard for 100Gbit/s links over copper cables and backplane links. Other efforts to define 100G and faster specs are in the works.

In a recent blog, John D'Ambrosia, chairman of the IEEE working group that set the 100G Ethernet standard, said several other new efforts may emerge at OFC. Specifically, he said there are needs for higher-density CFP modules and a new optical specification for 100G over 2km distances.

Members of the Optical Internetworking Forum (OIF) are participating in three events at OFC exploring networks beyond 100G. "Our members are leading the charge to bring 100G products to market quickly and cost-effectively, and are looking ahead to beyond 100G," said Lyndon Ong of Ciena, the OIF's vice president of marketing.

The OIF sponsored earlier this week a symposium on the debate over whether 400G or Terabit speeds should be the next big target. Speakers included Gary Nicholl of Cisco Systems, Tom Palkert of Luxtera, Drew Perkins of Infinera and Sterling Perrin of Heavy Reading.

The OIF participated in two future-looking sessions. A panel at the Service Provider Summit examined innovations and collaboration required beyond 100G with speakers from Deutsche Telekom and Verizon.

OIF members from Alcatel-Lucent, Nokia Siemens Networks and other companies talked about next-generation networking speeds in a separate session.

- Rick Merritt
??EE Times





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