The real definition of the metro optical network market includes technologies such as Gigabit Ethernet (GigE) (naturally), traditional Synchronous Optical Network (SONET), next-generation SONET, 10 GigE, Fibre Channel, and wavelength division multiplexing (WDM) technology. Cahners InStat/MDR expects this market to grow from a revenue base of $13 billion in 2001 to $23.6 billion in 2005, making it one of the fastest growing segments in the telecommunications industry. Cahners reports that from 2002 to 2003, legacy SONET/ Synchronous Digital Hierarchy (SDH) networks will still be expanded and upgraded as carriers weather the current economic climate. However, newly constructed networks that are designed specifically for data-centric traffic and based on next-generation optical network systems will offer the best hope for future profitability. Ultimately, these networks will lower operating costs, improve packet-handling efficiency, and position network operators to capture revenue from new services. The long-term forecast for U.S. and international metro optical markets remains very positive in spite of the telecom meltdown of 2001 and 2002.