TOKYO, Oct. 11 -- Nortel Networks is supplying its DWDM (dense wavelength division multiplexing) optical solution for ACCA Networks to strengthen its metro and relay networks in Tokyo, and to enable the expansion of high-speed (8 Mbs) DSL service in the cities of Tokyo, Chiba, Saitama and Kanagawa. Prior to deployment, ACCA and Nortel successfully tested the wavelength division multiplexing capability of the OPTera Metro 5200 and sent 40 gigabits of traffic over 16 wavelengths on current commercial optical fibers. This indicates that the infrastructure has been established to offer increasingly higher-speed DSL and FTTB (Fiber to the Business) services, as well as services such as Optical Ethernet in the future. The new network was constructed by installing metro DWDM systems in communications facilities that relay networks and by connecting them with metro ring high-speed optical communications lines. The infrastructure can provide networks with sufficient flexibility and can support networks offering broadband services and optical FTTB services, the demand for which is expected to rise. These optical metro networks also position service providers like ACCA Networks to drive significantly reduced operating costs, compared with existing networks, when the number of users increases.