Research On Survivability Mechanism In Multi-domain Optical Networks

With the rapid development of optical communication technology, especially the large-scaled deployment of optical network equipments and the wider application of various optical communication technologies, separated-domains management becomes an inevitable choice. In new generation intelligent optical networks based on wavelength devision multiplex(WDM), a large network is divided by the type of the equipments, the operators as well as the geographical constraints, thus forming multi-domain optical networks(MDONs). Due to the fact that each wavelength channel is bearing the order of Gbit/s business flow, any link fault will definitely leads to huge financial losses, which causes the survivability in optical network more and more crucial to study. However, domains separation results in imcomplete sharing of topology information, impossible to realize equipments interoperation bewteen domains but inter-domain connection requests keep coming, which undoubtedly puts forward higher requirements in survivability. Therefore, the multi-domain-based survivability have become the primary challenge in MDONs.In this paper, our research work focuses on the survivability mechanism in MDONs. Began with the technology background, the present research achievements and the technical challenges posed by MDONs are then analysed. According to the new requirements of survivability in MDONs, the related key issues are deeply studied and the direction of furture reseach work is further indicated.In order to solve the problem of effectiveness and accuracy for routing selection based on bandwidth and delay constraints as well as satisfying the requirements of the security and scalability in MDONs, a novel QoS-aware topology aggregation (TA) mechanism based on the thesis of full mesh aggregation is proposed, which can greatly improve the description accuracy for the actual network topology at the cost of increasing a certain amount of redundant control state information. The new TA mechanism is be proved to obtain not only the good performance in Error Rejected Ratio(ERR) for feasible requests and Crank Back Ratio(CBR) for unfeasible requests, but also a better trade-off between state information aggregated degree and description accuracy.Meanwhile, a heuristic multi-link fault-tolerant (MLFT) algorithm for survivability in MDON is proposed to resist multi-link fault at the same time, which applied Hamiltonian cycle protection (HCP) and segment-shared protection (SSP) to establish a novel survivability strategy for either intra-domain’s or inter-domain’s multiple links respectively. Furthermore, a new virtual links mapping scheme and link-cost formulas are presented to encourage the appropriate routing selection and load balancing, which can also contribute to better resource utilization ratio and blocking ratio. Simulation results show that MLFT realizes the multi-link fault-tolerant survivability at a lower cost with better performances in redundancy ratio, blocking ratio and computation complexity.