Because of the static nature of the deployed optical networks, large energy wastage is experienced today in production networks such as Telecom networks. With power-adaptive optical interfaces and suitable grooming procedures, we propose the design of more energy efficient transport networks. Optical network re-configurations are performed by GMPLS node controllers according to monitored traffic information. The investigated energy reduction strategies are simulated on two large scale transport networks (DT17 and COST37). The results show that the energy savings obtained by these strategies depend on the variability of the carried traffic and the characteristics of the network topology. For medium-size DT17 network significant (more than 37%) power savings are achieved only with symbol-rate adaptation while less savings are achieved for modulation format adaptation. In case of pan-European COST37 network, for both symbol-rate and modulation format adaptations significant savings are obtained. Mixed adaptation (jointly performing symbol-rate and modulation format adaptations) used together with optical grooming allows up to 44% and 47% power savings in DT17 and COST37 networks respectively, close to the optimum power savings case 48,2% computed when the power follows exactly the traffic demand pattern.

An analysis of the energy savings is presented when taking into account a complete traffic model for a one-year time period. Daily and weekly traffic fluctuations as well as yearly traffic growth are considered when analyzing the power consumption. Low power mode in optoelectronic devices (sleep-mode and rate adaptive capabilities) is implemented within a traffic-aware networking approach. The impact of dedicated 1:1 protection in a dynamic network scenario is considered and a comparison is made with the unprotected case. A GMPLS control plane is implemented and used to re-configure the power-adaptive devices and connections. Results show that symbol-rate adaptation provides high savings for unprotected scenarios (37% energy savings w.r.t. unprotected Baseline), while for the protected scenarios better results are obtained for modulation format adaptation which includes sleep-mode (57.1% energy savings w.r.t. protected Baseline). Moreover, compared to the Baseline scenarios the Mixed adaptation, combining both symbol-rate and modulation format, is the most power-efficient strategy providing 39% energy savings for unprotected scenario and 70% energy savings for dedicated protection scenario.

This study assesses the feasible energy savings when defining different service classes based on protection schemes in core optical networks. We propose a dedicated energy saving strategy for each of the service classes in order to minimize the overall power consumption of the network. Four Classes of Service are considered: platinum, gold, silver and best effort. Platinum connections benefit from a 1+1 protection scheme, gold connections and silver connections are assigned to a 1:1 protection with the difference that in case of gold connections the same pair of transponders is shared by the working and protection sections. Best-effort connections do not have any associated protection. Two scenarios are implemented and compared. The first, the baseline approach, does not take into account any traffic-aware strategies while the second one, the proposed approach, includes energy reduction strategies taking into account the sleep-mode capability of the opto-electronic devices as well as the elastic data-rate adaptation based on symbol-rate and modulation-format reconfigurations. The results show that in the baseline approach the power consumption is strongly dependent on the ratio between the different service classes while for the proposed approach the difference in power consumption is almost negligible. Moreover, in case of the proposed approach, silver service class can benefit for superior quality of service compared to the gold service class, due to the grooming mechanism.

We evaluate OSPF-TE extensions within GMPLS framework in support of flex-grid optical networks. Based on OSPF-TE LSAs, two routing strategies are proposed achieving up to 15% and 70% respectively improved blocking ratio for low loaded network (10-30 Erlangs) compared to the shortest path scenario.