Gig-E, G-PON, Gee-Whiz

The snappy marketers that drove the DSL industry to use 23 of the 26 letters of the alphabet to describe their technologies have moved to the optical access side of the house. We've now got A-PON (ATM passive optical network), E-PON (Ethernet PON) and G-PON (Gigabit PON).

Quantum Bridge's Charlie Guyer recently said, "When we started the company, there was no A-PON or E-PON, there was just PON. Now people are trying to divide it up and paint one as more beneficial than the other." That can get out of hand quickly, if history shows anything.

Those who watch for exciting new technologies understand the need to differentiate products. These signs of differentiation mean PON is having an impact on the market. Technology costs have come down to a point where deploying PON to small businesses and residences is starting to make sense. We're on the way, but we're not there yet.

PON provides interesting alternatives for delivering multiple services to businesses inexpensively. From an enterprise point of view, it doesn't matter what the specific underlying technology is, except as it affects the delivery of services.

Carriers using PON can't offer just data services if they're going to the trouble of upgrading old links to optical networks; they need to handle voice and video, too. That means supporting time-division multiplexing as well as IP - ATM, frame relay, private lines, audio links, the works. Customers want selectable services unconstrained by access type. Optical can and must fulfill that desire.

In the past, efforts to deploy optical technology in the local loop were hampered by insufficient bandwidth and limited to a single service. Not anymore. The latest products from vendors such as Alcatel, Quantum Bridge and others use PON technology to deliver multiple services and provide enough bandwidth to handle future services.

Scalability will be an issue with the early versions of PON, especially if the world keeps moving toward Gigabit Ethernet in the LAN, metropolitan-area network and WAN, streaming video, multimedia conferencing and so on. Even a small business will quickly need more bandwidth to keep up.

The E-PON crowd claims to offer the potential for lower costs, greater scalability beyond A-PON's 622M bit/sec and compatibility with the rest of the Ethernet world. But the group that helped develop the A-PON standard (G.983 from the ITU-T), the Full Service Access Network coalition, is working on a G-PON standard that will increase the bandwidth specified from 622M to 1.2G bit/sec.

Look for companies such as Salira Optical Network Systems and FlexLight Networks to come out with equipment in advance of these standards that potentially attains even higher bandwidths. Others will be there when standards solidify.

It's important to note the line rate has little to do with the underlying protocol and everything to do with the state of the (optical) art and the politics around the standards body. Until standards are set, you will likely see interesting innovations to increase capacity and improve operating efficiencies. To boost the capacity of single-fiber PON strands to as high as 10G bit/sec, some vendors have added dense wavelength division multiplexing and/or coarse wavelength division multiplexing to their PON gear. This lets carriers provide service at much lower costs. Companies might begin putting low-cost optical transponders on their premises to break out wavelengths from PON. So technology previously used only in long-haul networks is finding its way into small businesses and even homes.

The bottom line is that fiber is heading your way. As PON technology continues to mature and adds bandwidth and other capabilities, the economics for carriers - and therefore their customers - gets better, and deployment increases. But like everywhere else in the network, the movement toward Ethernet in the local loop is driving a lot of innovation and putting pressure on the ATM camps to innovate. That's great, because it's going to make more optical access available to more people, sooner.

Briere is CEO and McGuire is chief strategy officer of TeleChoice, a market strategy consultancy for the telecommunications industry. They can be reached at telecomcatalyst@telechoice.com.