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Industry Insights

Connecting WBMMF

Wednesday, January 4, 2017 | by Randy Harris

In this week’s CTD, our new Sr. Fiber Product Manager, Randy Harris, looks at some of the questions (and answers) to Wideband Multimode Fiber (WBMMF) for data centers.  While the all of the specifics haven’t been completely defined, WBMMF, along with higher speed transceivers and parallel optics, promises to extend link bandwidths from 10 G to 100 and even 400G over economical multimode fiber links.

OM5 | Wide-Band Multimode Fiber (WBMMF) Questions & Answers

What is OM5?

OM5 fiber is a new type of 50 micron core, laser optimized multimode fiber (LOMF) designed to provide better performance for applications using wavelength division multiplexing (WDM).  It operates over a wider window in the range of 850nm to 953nm to support at least four wavelengths.

OM5 specifications are included in the recently adopted standard document TIA-492AAAE ratified in June 2016.

Is OM5 fiber backward compatible with standard OM4 and OM3 fiber?

Yes, customers installing OM5 fiber today will be able to see the same performance and use the same applications as with OM4 fibers, at 850nm and 1300nm (if applicable).

Are there transceivers on the market today to support OM5?

Presently no, but we can expect the first ones to be available by 2017.  We know that fiber transceiver solutions are in development (at companies like Finisar) that will utilize four wavelengths over OM5 fibers.  This is currently referred to as SWDM4 for “Short Wavelength Division Multiplexing over multimode fiber using 4 wavelengths”.

Is there a specific color for OM5 cable?

The current standard does not provide any guidelines in regards to the color of the cabling or the connectivity.  However, some manufacturers have already adopted the lime green color.  The TIA has not decided on a recommended color at this time.

The color is expected to be discussed at the next TIA meeting in February 2017.

How does it affect the fiber plant?

If SWDM4 transceivers were available, you could support up to 100GbE with duplex fibers.  It would reduce your fiber count by at least four for applications above 10GbE.  For example, 400GbE could be accomplished with 4Tx and 4Rx fibers (today 400GbE over multimode requires 16Tx and 16Rx fibers).

How do I know (identify) that I have an OM5 fiber cable installed?

There is no specific color that has been adopted by the industry or recommended by TIA for OM5 cabling. The “OM5” designation will most likely be printed on the cable.

What is the effective modal bandwidth (EMB) of OM5?

OM5 fiber has the same effective modal bandwidth (EMB) as OM4, at 850 nanometers: 4,700 Mhz-km.

Since bandwidth directly impacts distance, a table has been provided at the end of this CTD  for reference.  It lists the distances supported by each of the different fiber types, both multimode and single mode, for several current applications.  There is no specific application that has defined OM5 as one of the fiber types since it is so new.  Therefore, OM5 can support the distances that OM4 supports for existing applications.  Application distances supported by new equipment/transceivers, utilizing OM5’s ability to support at least four wavelengths, will initially be transceiver specific.

Who has OM5 fiber cabling solutions?

The OM5 glass is available to all manufacturers.

Are the connectors and adapters different for OM5 fiber?

Standard multimode connectors and adapters for OM3/OM4 will work with OM5 fibers.  The only difference will possibly be the need to change the connector and adapter housings or boot colors to allow easy identification of installed OM5 connections


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