Flexible architectures for optical transport nodes and networks

TLDR

Flexibility to support mesh topologies, dynamic capacity allocation, and automated network control and light‑path setup is essential for next‑generation optical transport networks. The article aims to present architectures and various ROADM implementations—colorless, directionless, and contentionless add/drop structures—to realize this flexibility. The authors describe reconfigurable ROADM architectures featuring dynamic add/drop structures, embedded control planes, colorless/directionless/contentionless add/drop, variable channel bandwidth for bit rates beyond 100 Gb/s, and automated provisioning and restoration via GMPLS and optical measurements. The review shows that scaling bit rates beyond 100 Gb/s necessitates ROADM architectures to provide variable channel bandwidth, influencing their design.

Abstract

Flexibility to support mesh topologies, dynamic capacity allocation, and automated network control and light path setup are key elements in the design of next-generation optical transport networks. To realize these capabilities, reconfigurable optical add/drop multiplexers with dynamic add/drop structures, embedded control planes, and lightpath characterization are required. This article presents the architectures and various ROADM implementations including colorless, directionless, and contentionless add/drop structures. The effect of scaling bit rates beyond 100 Gb/s on ROADM architectures is reviewed including providing variable channel bandwidth depending on bit rate. Automated provisioning and restoration using the GMPLS control plane and optical measurement approaches for lightpaths are also discussed.