Study On Survivability And Self-Healing Technologies For Broadband Transport Networks

In information age, human have been heavily depended on reliable operation of communication networks, especialy on the continuous operation of backbone networks. In fact, all services and logical networks, including the Internet, share physical transport on relatively few backbone fiber optic transmission systems. With recent advances in (D)WDM-(Dense) Wavelength Division Multiplexing technologies, the potential for enormous bandwidth in a single optical fiber has been exploited and hence the network survivability has become more urgent. This dissertation focuses on survivability and self-healing issues of broadband transport networks: the dynamical pre-configuration of the P-cycles, network planning with joint the pre-configuration and the pre-planning method as well as BLSR (Bi-directional Line-Switched Ring loading) loading problem.The author proposes a fast P-cycle pre-configuration searching algorithm in a mesh network, which can speed up the searching process convergence through two approaches. 1) A multi-capacities P-cycle (which was configured through multi searching waves in classical algorithm,) can be abtained within one searching wave with the algorithm, which make it faster than classical one.2) Instead of cycle-based searching, path-based searching approach is used. With the path-based searching techniques, searching tasks originally for a node can be distributed to multiple adjacent nodes, so as to speed up the searching process. The simulation result also shows that the penalty to spare capacity needed is very small with the new algorithm apart from the reduction in the number of searching waves. Furthermore experient also shows that the larger network scale is, the better performace one can get with the new one.A survivable network planning strategy based on combined pre-planningwith pre-configured method is proposed in Chapter 3. The approach can satisfy the requirement of differential services, i.e. provisioning fast protection for most important demands and fast restoration for sub-prior demands and with high efficiency of spare resource usage. Non-protected transmission capacities can be classified into two types: Generally Unprotected Capacity and Preemptive Unprotected Capacity. Through performance simulation to fixed span capacity network model, relationship of two types of non-protected capacity and network protection ratio was established and high efficiency can be obtained via a trade-off between protection ratio and the length of restoration path.An especially important sub-problem in the design of whole networks is the loading of demands into BLSR. We prove that this problem is a NP-Complete problem and propose a lower bound evaluated algorithm and two heuristic algorithms. The first approach is a greedy algorithm. Another approach, which is basis on the result of the first one, is the dual-ascent method. It exploits the LP-relaxation of BLSR-L and its associated dual LP. Simulation results show that the second approach can improve the loading efficiency obviously.