Mesh Wdm Optical Network Survivability Protection Algorithm

With the rapid development of Internet traffic and the tremendous demand in bandwidth and capacity, the Wavelength Division Multiplexing (WDM) technology will become the core of the next generation backbone networks. The concept of constructing the optical layer or virtual topology over the physical networks through the WDM technology and wavelength routing will become the important transmission method in the future backbone networks. Since a single wavelength channel has the transmission rate over several gigabits per second, the failures of fiber links or nodes may lead to large data loss. Therefore, the survivability design has emerged as one of the important issues in WDM optical networks. The strategy of survivability mainly concludes into two types: protection and restoration. In protection, the backup resources will be pre-assigned to against the future unknown failures. In restoration, the backup resources are not be pre-assigned; after failures occurring, the backup resources will be assigned dynamically according to the current network state. With the concept of survivable design, this dissertation investigates the survivable design in WDM mesh networks, including: hybrid survivable design under the single-link failure, time aware availability guarantee scheme, and triple-link failures protection in three-connected WDM mesh networks.In these studies, the researchers have focused their attention on a single class of traffic. In practical network services, different connections will have different service level requirements. It is important to differentiate the priority of traffic requests. We will provide shared path protection for high priority traffic, and restoration for low priority traffic. This hybrid survivable design will use the network resource efficiently, because it combines the benefits of protection and restoration schemes. It will have a good performance in resource utilization ratio and blocking probability. Currently, some papers only use Integer Linear Program to describe the objective problem and optimize the network resource. But the authors do not describe the detailed heuristic algorithm. Based on this, in chapter 2, the authors do research on the problem of hybrid survivable schemes in WDM mesh networks, the main contributions include: 1) propose the detailed priority-based heuristic algorithm. 2) Propose the new rules of resource sharing to improve the resource utilization ratio. So the authors propose the Enhanced Resource Shared Algorithm which adopts the new rules of resource sharing and does it best to use the low priority traffic resource as the backup resources of high priority traffic. The simulation evaluates the performances of ERSABy different requirements of availability, the service provider can assign reasonable resources to serve different users to optimize network resource utilization. In chapter 3, the authors study the availability guarantee problem, the main contributions include: 1) analyze the problem of time unaware availability guarantee scheme and its availability computing model. 2) Propose a time aware availability guarantee scheme. The key property of time aware availability guarantee scheme is adjusting the backup resources according different availability requirements during the connection holding time. The simulation results show that this scheme have good performances in resource utilization ratio, blocking probability and throughput per connection.In current network, as the size of network increasing, the services carried in optical backbone network are intent to be diversification. Some customers will not just need the ability of surviving double-link failures. Furthermore, they want to survive the triple-link failures. Previous references have propose the typical algorithm for double-link failures which will compute the primary path firstly, then remove the links along the primary path and compute two risk-disjoint backup paths. The similar process can apply into the problem of triple-link failures. We should find out one primary path and three link-disjoint backup paths. However, it is impossible to find out four link-disjoint paths in a three-connected WDM mesh networks. The authors focus on this problem, and the main contribution is that we can solve this problem using sub-backup paths and propose a Triple-link Failures Protection Algorithm which will compute the sub-backup paths not only from source node to intermediate nodes but also from the destination node to intermediate nodes.To verify and evaluate the proposed algorithms in this dissertation, simulation platform software is developed. Based on the platform, the performances of all proposed algorithms are evaluated. The platform, model structure and some pseudo codes are given in chapter 5.