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WDM PON: Sooner Rather Than Later?

For several years, a religious war has raged between advocates of different flavors of fiber to the premises (FTTP). In one camp are supporters of point-to-point (P2P) Ethernet, led by Cisco Systems Inc. (Nasdaq: CSCO). In the other, passive optical networking (PON) fans are divided between Gigabit Ethernet PON (GEPON), used mainly in Japan; and Gigabit PON (GPON), led by Alcatel-Lucent (NYSE: ALU). For those deploying FTTH networks, this industry divide makes it tougher to make technology choices.

But this war could come to an end sooner than anticipated, because Wavelength Division Multiplexing (WDM)) PON, a technology that could unite the warring tribes, may not be as far off as we all thought. Although many still believe that WDM PON remains too expensive, too immature, and not deployable before 2011 at the earliest, an increasingly vocal minority suggests that the technology is maturing a lot more quickly than expected and could be widely deployable as early as late 2009 or 2010.

If that's really the case, it raises some pretty big questions about which technologies will ultimately dominate FTTH deployment, because the truth is that we are still at a very early stage in the transition. Of the world's 2 billion homes, only about 20 million have fiber. Except in Japan and Korea, fewer than 10 percent of homes are connected, leaving a big open question about how the rest will be hooked up. (Many, of course, may never get fiber at all, but that is a question for another column.)

There are, to be sure, some big issues before WDM PON can really play in the big league. A key reason that the incumbent telcos outside Japan are mostly opting for GPON is that it's an International Telecommunication Union (ITU) standard. WDM PON is not, and is unlikely to be a complete standard for a year or two yet. Some vendors and telcos, meanwhile, continue to argue that 10-Gigabit GPON is the way to go next – raising the prospect that the standards war could continue to rage in another form. Meanwhile, others assert that simple P2P Ethernet offers a long-term solution that can scale up in bandwidth indefinitely.

But whatever the uncertainties, the fact is that WDM PON is a highly attractive approach that can provide more than enough bandwidth for at least a decade or more, and could line the industry up behind a single approach. That would be of huge benefit in pushing FTTH forward and bringing fiber to the masses faster.

At the same time, however, the rapid rise of WDM PON would – at least in the short term – introduce yet another option to builders, potentially resulting in further delays in deployment. One vendor told me of a European incumbent that has put GPON plans temporarily on ice while it takes another look at the potential of WDM PONs. Could others follow? We'll be tracking developments closely and reporting back what we find.

— Graham Finnie, Chief Analyst, Heavy Reading

rs50terra 12/5/2012 | 3:37:42 PM
re: WDM PON: Sooner Rather Than Later? WDM PON actually builds on GPON/GEPON using CWDM or DWDM technology to overlay PONs of different wavelengths over the same fibers. So the GPON vs. GE-PON 'war' is on.

A second question that should be asked is: isn't it time to revisit the question of PON vs active Ethernet? In many cases, the optical splitter is located in the CO and therefore the fiber infrastructure is identical irrespective of whether one uses PON or active Ethernet. The question remains what makes more economic sense: a WDM-based solution with all the associated costs (manufacturing and management) or a standard solution based on ubiquitous 1GE transponders.
Well?
optical Mike 12/5/2012 | 3:37:40 PM
re: WDM PON: Sooner Rather Than Later? A second question that should be asked is: isn't it time to revisit the question of PON vs active Ethernet?
In many cases, the optical splitter is located in the CO and therefore the fiber infrastructure is identical irrespective of whether one uses PON or active Ethernet.

I would disagree on your statement GǣIn many cases, the optical splitter is located in the COGǥ because in PON deployments very few of the splitters are located in the central office.
ThatGs one of the fundamental advantages of PON. You deploy one fiber to the area you are going to serve and locate the splitter there then you run the fibers to your 32 or 64 subscribers as opposed to running an individual fiber from the CO to each subscriber
cw.774 12/5/2012 | 3:37:36 PM
re: WDM PON: Sooner Rather Than Later? Active Ethernet can be supported over a PON or a typical full duplex fiber no matter where the splitter is. But you can't opreate both at the same time sharing the same wavelength (like 1310nm which is PON upstream and LX tyical lambda) unless... you start playing games with wavelegnths for overlaying technologies... and then you have the WDM network... woops, I brought things full circle
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