Engineering 400G for Colorless-Directionless-Contentionless Architecture in Metro/Regional Networks [Invited]

Metro/regional networks are beginning the transition from 10 to 100 Gb/s on dispersion unmanaged optical links. Long-haul networks have a head start in the move to all-coherent networking and have popularized route-and-select-based node designs and colorless, directionless, and contentionless add/drop structures. Both metro and long-haul coherent networks are expected to support future 400 Gb/s transmission. This paper examines the node architecture and 400G transmission options for coherent metro networks with the distinctive characteristics of short spans and high optical filtering penalties. Reach results are derived for signals based on 100, 200, and 400 Gb/s superchannels. Additionally, blocking probabilities are reported for two approaches to nodal add/drop architecture. The results provide a clear direction for metro/regional node and network architecture decisions.