OIF Sets Component Specs

The Optical Internetworking Forum (OIF) is planning to announce four implementation agreements tomorrow in a move that could encourage adoption of emerging technologies such as tunable lasers, optical crossconnects, and 40-Gbit/s transmission systems.

The implementation agreements pave the way for systems vendors to source components from a variety of suppliers, knowing that they will meet their needs. It also makes it easier for components suppliers to design parts for these applications, which will speed up the development process.

"These technologies are in a pre-competitive phase where it's better for everyone to work together to benefit the industry as a whole," says Steve Joiner, OIF technical committee chairman.

The four areas covered by the new standards are:

  • Tunable lasers: The agreement defines electrical interface, communication protocol, and physical form factor for tunable laser modules. Tunable laser vendors had previously flirted with the possibility of producing a multisource agreement (see Laser Suppliers Getting in Tune). But in the end they decided to develop common configuration through the OIF. The OIF process involves wider participation, so the end result is better, says Joiner. More than 20 companies participated in the creation of the OIF specification, including system vendors as potential customers, and chip makers, as potential suppliers.

    One thing not specified by the OIF is optical performance. That's because there are many different applications for tunable lasers, and it's too early to say what the required parameters for those applications will be. However, according to Eric Selvik, who represents OIF member company Iolon Inc. there's a lot of momentum behind taking this to the next step -- a multisource agreement -- "which would include optical parameters."

    Tunable laser vendors could have OIF-compliant modules out before the end of the year, according to Selvik.

  • OC768 optical links: VSR-5 is the latest addition to the Very Short-Reach Sonet group of specifications. It describes a number of different ways of sending 40-Gbit/s signals over short-reach optical links. The completion of this agreement is especially important given that OC768 is expected to take off first in short-reach, high-bandwidth pipes to connect equipment inside the central office.

    The agreement defines electrical and optical parameters, as well as ways of muxing and demuxing of signals onto slower connections. There are many different flavors, including: 12-channels of 3.125 Gbit/s; a 4-channel version; a serial solution. On top of that, there are subcategories depending on what wavelengths are used. Some might say there are too many choices, but the OIF's Joiner says it's important not to close off any options too early.

    "It's our job to set out the possibilities," he says. "Then we let market forces loose on it." Right now, it's still early days, and its hard to work out which technologies will prove to be cheapest.

  • Optical crossconnects: A new standard, VSR 4.5, allows for ways of moving OC192 (10 Gbit/s) signals over optical crossconnects inside a central office (under 600m). There is already a VSR-4 standard for 10-Gbit/s links. This one differs by having a much higher optical link budget to allow for losses in the crossconnect: 11 dB as opposed to 4dB.

  • SFI-4.2 (SerDes Framer Interface): Last on this list is an electrical interface designed for shifting OC192 signals between framers and SerDes chips, with FEC (forward error correction). It's basically a more compact version of an existing standard SFI-4.1, which, employing 16 channels at 622 Mbit/s, is used in all 300-pin DWDM transponders. The new agreement is driven by space constraints inside networking gear, which has created a need for fewer pins on each interface. The result is an interface that moves OC192 using just four channels.

— Pauline Rigby, Senior Editor, Light Reading
www.lightreading.com Want to know more? The big cheeses of the optical networking industry will be discussing tunable lasers, optical crossconnects, and 40-Gbit/s transmission systems at Lightspeed Europe. Check it out at Lightspeed Europe 02.

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