Application of Reconfigurable Optical Add / Drop Multiplexers in DWDM Networks
Background. Modern OTN-DWDM optical transport networks have complex topologies, with more than one route between any two network nodes. Dynamic optical routing of spectral channels is required for flexible network management and to ensure reliable and uninterrupted operation. Spectral channel routes in OTN-DWDM networks are created using optical add / drop multiplexers (OADMs). Passive OADMs, based on optical filters, do not allow route changes without physical equipment replacement. Therefore, reconfigurable OADMs (ROADMs) are used in modern networks, enabling dynamic channel rerouting. Purpose. To qualitatively assess the effectiveness and feasibility of using ROADMs in OTN-DWDM networks based on a comparative analysis of their structural diagrams and architectures. Results. The operating principles and structural diagrams of ROADMs and their main components--wavelength-selective switches (WSS)--for DWDM networks using fixed and flexible spectral channel grids are examined. A comparative analysis of ROADM architectures (Colored, Colorless, Directionless, Contentionless, Broadcast-and-Select, Route-and-Select) is conducted. Recommendations for selecting a ROADM architecture for an OTN-DWDM transport network are provided. Practical relevance. The proposed recommendations for selecting a ROADM architecture can be used in the design and modernization of OTN-DWDM networks to reduce operating costs and improve network resilience.