Multi-objective Design of Survivable Flexible-Grid DWDM Networks

Emerging trends in optical transport networks aiming to support increasing data rates are reshaping the possibilities for network planning. The deployment of a flexible grid with multiple available channel bit rates and spectral widths gives way to a more clearly defined trade-off between spectrum and cost in the planning process. Furthermore, providing redundancy in these types of services is both crucial and costly. For this reason, it is important to consider all these aspects simultaneously in order to have an accurate view of the cost/spectrum trade-off in the optical backbone. This paper presents an evolutionary based multi-objective framework for optimizing network deployments with flexible-grid channel formats ranging from 40 to 400 Gbits/s with varying degrees of resilience to both link and transponder failures. The multi-objective algorithm can consider all these different aspects simultaneously and highlight the degree to which cost can be traded for spectrum, and how the protection/restoration schemes influence both parameters. After benchmarking the proposed algorithm on both objectives, we use it on two reference networks to trace the non-dominated front for multiple resilience schemes, offering different levels of protection against link and/or transponder failures. We also evaluate how the channel format selection for each demand evolves when considering single-rate or bit-rate variable transponders.