SURVIVABLE GREEN OPTICAL BACKBONE NETWORKS WITHSHARED BACKUP PROTECTION

Sammanfattning: With the rapidly growing power consumption in Information and Communication Technology (ICT), energy-efficient solutions in telecom networks have become increasingly important. As a part of telecom networks, optical backbone networks are also becoming a part of the overall power consumption. Moreover, in order to meet high reliability requirement of a network serving a huge amount of data transmission, backbone network infrastructures are deployed with redundant resources taking into account the backup capacity for protection. Therefore, energy-efficient approaches in optical backbone networks need to consider minimizing power consumption and backup capacity at the same time. This thesis analyzes the impact of green routing and design techniques on different protection schemes thoroughly by proposing optimization models to obtain optimum solutions under various objectives: Minimizing consumption of (I) Capacity, (II) Capacity + Power and (III) Power. Two different shared backup protection (SBP) schemes: (1) SBP-dep (failure dependent) and (2) SBP-ind (failure independent) are compared with dedicated path protection (DPP). It is assumed that network links utilized by only backup paths can be put into sleep mode. It is observed that when power consumption is minimized the backup sharing decreases in SBP and, in the extreme case, it behaves similar to DPP. When the objective is to minimize power, we need to trade capacity consumption, especially in terms of primary wavelength usage, since the primary paths need to be packed and therefore may take longer routes while backup paths can be put into sleep mode. Packing primary paths results in less number of link-disjoint primary paths which degrades shareability of backup wavelengths implicitly and leads to an increase in backup capacity consumption. Energy-efficient routing tends to pack while survivable strategies try to spread the traffic. In order to address this trade-off, a multi-objective approach which achieves a good compromise between power and capacity consumption is proposed. The results of this contribution are not presented in this document since they are to be included in an article and submitted to a scientific journal. However, as the problem is NP-complete, ILP solutions are not scalable for larger problem instances. Therefore, a novel energy-efficient and survivable routing and network design algorithm addressing the trade-off caused by conflicting objectives of energy efficiency and survivability is proposed in this thesis work. Moreover, various survivability mechanisms are investigated under the impact of energy-efficient strategies.