Optical networks are paving the way for a brave new world of cheap bandwidth, instant connectivity and seamless communications.

But predicting when that day of optical networking bliss will actually get here remains a slippery target. While Richard Cunningham, a senior analyst with Cahners In-Stat Group, sees the optical networking market growing very fast, he warns that legacy systems have a way of hanging around.

"Legacy equipment has a tendency to last for a long time," Cunningham says. "Legacy equipment lasts much longer than proponents of a new technology would have you believe."

Sterling Perrin, a research analyst with International Data Corp. (IDC), says he thinks there¹s little point in talking about the "rise" of optical networks because much of the technology has already been adopted by a majority of carriers. Rather than seeing a direct competition between legacy systems and cutting-edge optical equipment, Perrin says technologies like dense wavelength division multiplexing (DWDM) and ultra long-haul cable are being added to existing networks to increase their data-carrying capacity.

DWDM allows multiple light wavelengths to carry data in the same strand of optical fiber. This means that the capacity for optical fiber to carry data can increase dramatically without actually increasing the amount of fiber that¹s needed to carry that data.

Sycamore Networks, for example, has ridden the wave of DWDM technology in its three-year history. And Perrin sees a lot more room for growth within the DWDM market.

"Data traffic·Internet traffic·is not slowing down," Perrin says. "DWDM is proving to be the best way to scale a network."

In addition, he says, carriers are installing ultra long-haul equipment that can carry a light signal vastly longer distances (around 600 km compared to stretches of up to 3,000 km) before requiring electrical regeneration·a technological advance that requires less switching equipment for existing networks.

Of course, Perrin says, there are different levels of how aggressively carriers are pursuing optical networking. He sees new carriers building DWDM networks from scratch·and even all-optical networks·never even bothering with SONET (synchronous optical network) ring standards, much less ATM (asynchronous transfer mode).

At the same time, he doesn¹t expect older carriers to scrap their existing equipment in favor of new optical technologies, but rather to phase in one technology as the other withers into eventual obsolescence.

The shift that is occurring towards optical networks·those that are based on the SONET ring communication standard but with smarter features like DWDM and ultra long-haul equipment·presages the eventual adoption of an all-optical network. Where today¹s networks, whether SONET or ATM, rely on data being converted to electronic signals, the all-optical network will eliminate data having to be "switched" from electricity to light again.

In a world of the all-optical network, any type of traffic, including voice or video, would travel as optical data packets. It¹s as if the telecommunications infrastructure would become one giant local-area network, allowing bandwidth and speed capacities to reach mind-boggling capacities.

While Perrin says electrical switching will be around for "years to come," that doesn¹t mean the world can¹t get a taste of an all-optical network today.

"You¹re actually starting to see an all-optical network with Broadwing right now," he says, noting that while the company¹s network is still in experimental mode, it¹s significant that an all-optical network has been deployed.

But at least two newcomers are betting that major carriers such as AT&T, Verizon and BellSouth will adopt optical networking infrastructure much more slowly than anyone predicts. WaveSmith Networks plans to release a switching device in June designed to operate on an ATM network that can also be easily configured to handle other kinds of traffic, including Internet protocol. The same is true for WaveSmith¹s neighbor, Gotham Networks, which offers a similar multi-service switch that will allow for a migration path from ATM to other kinds of traffic.

No matter how long ATM hangs around, however, it won¹t necessarily impede the growth of optical networking equipment. Perrin says the optical equipment being purchased now is at a different protocol layer than ATM and SONET, allowing for co-existing markets.

Cunningham says the $20 billion North American market for optical networking, which includes not only the network infrastructure but also the equipment that goes along with it, will likely double by 2005. However, the big question mark he sees now, as do many other tech experts, is how deep a possible recession might be.

"If business as a whole slows down, slowing down the growth of the Internet, then it could delay the growth of the market," Cunningham says. "But, if things pick back up, then you could start to see strong growth."

Despite what happens in the long run, Perrin says he sees one undeniable trend in today¹s optical networking market: "There¹s a lot of money being spent."