10:00 AM -- Despite all the tests, GPON interoperability has never been fully tested. One hangup is the ONT management control interface (OMCI), the communications protocol between the central office and customer premises devices.

OMCI was one of the last pieces of the GPON standard to fall into place, in 2004. (See PON & FTTx Update, from 2005.)

And no one's used it since.

"It's arcane, and service providers don't like arcane," says Steven Glapa, vice president of product managment for Zhone Technologies Inc. (Nasdaq: ZHNE). "What many vendors in the space have done is paper it over with proprietary management."

Here's what it does. The Optical Network Unit (ONU) (also called ONT, for optical network terminal) is a blank slate, with no built-in configuration. So, unlike a DSL modem, the ONU needs to take instructions from the central office every time there's a change -- a reboot, for instance. OMCI is the protocol for carrying those instructions.

But OMCI requires too much work for the service provider; Glapa likens it to having to write your own Windows driver for every printer you use.

There's a bigger reason for OMCI to be ignored, though. The protocol would be a crucial step in true interoperability, letting service providers connect any vendor's ONUs to any Optical Line Terminal (OLT). That's great if you want to buy cheap ONUs. It's less great if you're, say, Alcatel-Lucent (NYSE: ALU), Motorola Inc. (NYSE: MOT), or Tellabs Inc. (Nasdaq: TLAB; Frankfurt: BTLA), and you want carriers to be buying your ONUs. (That's true of any big company; I'm just picking on the North American ones.)

So, while the Full Service Access Network (FSAN) organization has tested GPON interoperability before, it's never been real interoperability. This week, they'll get closer, because OMCI will be part of the FSAN interoperability trial that's going on in Sophia Antipolis, France. (Amazingly, Light Reading did not grant a travel budget for editors to attend.)

"This is the first one where all the layers of management, all the way to OMCI, are going to be dealt with," says Geoff Burke, director of marketing at Calix Inc. (NYSE: CALX)

Zhone, for one, wants to show it's on the OMCI train. It's recently launched its MXK system, which includes a feature called Smart OMCI, trying to make the protocol easier for carriers to use. (See Zhone Releases Son of MALC.) As for the rest, I'd guess their OMCI implementations will play together well, since the test is not a pop quiz; they wouldn't test OMCI if vendors didn't say they were ready, right? How quickly anyone feels like implementing it is another matter.

— Craig Matsumoto, West Coast Editor, Light Reading