Multi-Layer Network Optimization: Benefits of Elastic Optical Networks

In this paper we study multi-layer optimization of IP over DWDM core network with constraints of energy consumption and CAPEX. Population related IP traffic mapped to the optical DWDM layer together with leased lines form basic traffic load, which is expanded by a factor of 33 and 100 for a 10-year projection. These traffic loads are analyzed for mixed-line-rate and reach/bandwidth elastic network scenarios; the latter one is realized by optical orthogonal frequency division multiplexing (O-OFDM). We also study the effect of routing restrictions achieving networks with and without hierarchy, and of different approaches of frequency grids for DWDM channels. Keywords: optical networks, network optimization, multi-layer networks, mixed-line rates, optical OFDM, elastic networks. 1. INTRODUCTION The continuously increasing growth of IP traffic is mainly driven by Video on demand, IPTV, cloud computing, etc., and requires: (1) Cost effective (CAPEX and OPEX) future networks featuring high flexibility for introduction of new and customer related services in the network and (2) highly efficient use of the available optical bandwidth of the fibre. Thus, alternatives to the ITU 50 GHz wavelength grid for transmission of DWDM channels in an optical network are of great interest to increase the transmitted information spectral efficiency and to reduce the cost per transmitted bit. Several concepts have been proposed: (1) use of no fixed wavelength grid (grid less) [1] and use of 12.5 GHz frequency slots (flex-grid) [2], [3].