Greening the multi-granular optical transport network design under the optical reach constraint

Significant portion of the energy consumption of the optical networks is expected to be in the transport segment. Besides its improved bandwidth utilization advantage, multi-granular switching concept further helps rectifying the energy bottleneck problem in the backbone. One of the important challenges faced by the multi-granular optical networks is the optical reach enforcement. In this paper, we compare the multi-granular optical network design to the conventional Wavelength Division Multiplexing (WDM)-based network design by enforcing the optical reach limitation as a design constraint. We introduce the heuristics to solve the Routing and Multi-Granular Path Assignment (RMGPA) problem. Our simulation results show that multi-granular optical network design outperforms the WDM-based network design in terms of Operational Expenditure (Opex) as it significantly reduces the power consumption in the backbone. Furthermore, through simulations, we show that the green multi-granular design is efficient in terms of the Capital Expenditure (Capex) as the network cost is also degraded.