Building a new highway can cause major headaches in the form of traffic congestion, cost overruns, and social dislocation. Just ask the residents of Boston, where the "Big Dig" is in the process of taking an elevated, overcrowded six-lane highway that cuts through the city, and burying it in a ten-lane tunnel that will run under a park. Local traffic will be efficiently distributed by a new network of surface streets and on-off ramps, while through traffic will be able to travel at high speed below ground.

That's the theory anyway, and you can probably see where I'm going with this analogy about metropolitan traffic flow and metro WDM. There's no easy route to building metropolitan and access optical networks that will really meet the needs of businesses and consumers. We've already done considerable work on building out the long-haul networks that span continents. There are certainly more to be built and improvements or refinements to install, but in retrospect, long-haul will look like the easy part.

In the first place, it's not altogether clear what metro networks should or could look like, with options for overlapping or competing versions of WDM, SONET/SDH, Fibre Channel, and Ethernet. In addition, the existing local phone networks are hardly optimized to support high-speed data transmission, and both incumbent and startup providers face considerable hurdles to increasing capacity and offering new services.

Still, it's a sector that continues to attract investments and forecasts of strong growth. KMI, a research arm of PennWell, says the combined metro, access, enterprise, and CATV markets in 2001 will total over $1.3 billion, rising to $5.8 billion in 2005. At that point they will equal roughly one quarter of the long-haul WDM market, but will have grown at a considerably faster clip.

Some of the technical options for metro WDM are nicely reflected in our lead feature by Michael LaHa at Blaze Network Products, who argues that coarse WDM presents a low-cost way of extending Ethernet beyond very-short-reach applications. Gerlas van den Hoven and John Wachsman at Genoa then discuss the amplification needs of metro systems and the roles that different amplifiers can play. Finally, David Richardson and his colleagues at the Optoelectronics Research Centre of the University of Southampton introduce an alternative—or embellishment to—metro WDM, optical-code-division multiple access technology.

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The beautiful scene on the cover of this magazine was created long before the terrible events of September 11, 2001. Yet it can serve to remind us of all that is best in a city and its citizens. Our thoughts and deepest sympathies go to all the victims' families and friends, to the brave rescue crews, and to everyone affected by the unconscionable acts of destruction.

W. Conard Holton
Associate Publisher/Editor in Chief

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