Energy considerations in EoS-over-WDM network configuration

Optical network nodes typically have to process varying traffic volumes and should therefore be configured optimally to service traffic at the lowest cost possible. We model an Ethernet-over-SONET/SDH-over-WDM network (to represent a metro optical network) and define the network cost incurred in terms of energy consumption and capital expenditure. We then propose an exact integer linear program to minimize either cost, with and without considering traffic survivability, in order to study the energy consumption of different network configurations. Our results for a realistic network show that capital expenditure optimization would result in a more future-proof network configuration, at only slightly higher energy consumption than the energy consumption optimization. When survivability is achieved by a 1+1 protected lightpath scheme, the network energy consumption is shown to be almost twice the energy consumed by a 1:1 protected lightpath scheme, due to the redundant use of line cards. We also study the effect of a single link addition to the network, which reduces the average shortest path length and increases the survivability of the network, at the expense of slightly higher network energy consumption.