An in-operation planning tool architecture for flexgrid network re-optimization

In-operation network planning consists in re-optimizing a network, currently being operated to transport traffic, either minimizing resource utilization or maximizing the transported traffic. In the context of flexgrid optical networks re-optimization includes spectrum defragmentation, virtual topology reconfiguration, etc. To perform in-operation planning, a centralized element in the control plane is needed to efficiently coordinate the elements in the data plane. The active stateful Path Computation Element (PCE), able to update already established connections, can play the above role. Notwithstanding the active stateful PCE, to fulfil the required in-operation planning functionality a tool with a number of interfaces to populate and synchronize databases as well as to attend for re-optimization requests should be implemented. In this paper we propose an in-operation planning tool architecture specifically designed to be connected to the front-end PCE. To illustrate its operation, we study a specific use case: the defragmentation problem to reallocate already established connections so as to make enough room for an incoming request.