Though the main long-term driver for deployment of 40 Gb/s systems is the lower cost per managed bit per km, a main near term driver for deployment of 40 Gb/s transport system is the need to support 40 Gb/s services. High-end routers with OC-768/STM-256 interfaces are on the horizon prompting many carriers and service providers to prepare their backbone network to 40 Gb/s data rates. This is because native 40 Gb/s services can more efficiently be transported by a 40 Gb/s line rate rather than using a costly and complicated inverse-multiplexing transport scheme that is also difficult to maintain and manage. Moreover, by adding 40 Gb/s data rates on the last wavelengths in an installed 10 Gb/s system provides a cost effective means to upgrade capacity constrained 10 Gb/s systems, thereby offering carriers and service providers the opportunity to postpone an expensive new network installation.