Global concurrent optimization: Advantages and opportunities in flexgrid-based networks

In future flexgrid core networks the amount of lightpaths might increase significantly as a consequence of the finer granularity in the use of the optical spectrum. Different spectrum bandwidth can be allocated to each lightpath as a function of, among others, the bitrate amount to be conveyed and the modulation format used. As result, spectrum fragmentation might appear leading to non-optimal resource utilization. In addition, a failure in a fibre link could trigger hundreds, or even thousands, of path computations requests to a centralized Path Computation Element (PCE). Latter examples can benefit from using the recently standardized Global Concurrent Optimization (GCO), which enhances PCE´s computation capabilities. In this paper we present two opportunities to take advantage of the PCE+GCO architecture: spectrum defragmentation and restoration.