Spare capacity reduction using vertical sharing in multilayer mesh restorable network

Telecommunications networks have a multilayer structure, each layer has a different technology and different provisioning unit. This multilayer structure complicates the network survivability system design. Most past research was focused on the single layer design and less attention was given to the survivability system for multilayer telecommunications network even though most telecommunications networks consist of multiple layers. In this dissertation, a survivability system design for a multilayer telecommunications network is provided to address two major problems. The first problem is the unharmonized operation of independently designed network survivability systems for a multilayer telecommunications network. Single layer design has a limited view of interoperation with other layer's survivability systems. So there is a possibility of unharmonious operation. The solution of this is to design a network survivability system in an unified framework as a single entity. The second problem is unclear spare dimensioning a among layers; traffic from layers is encapsulated through multiplexing hierarchy then transmitted over an optic cable, so spare capacity assigned in a higher layer is multiplexed into lower layers and takes capacity in, lower layers. But a single layer design doesn't have this multiplexing view so when the single layer design is applied to multilayer telecommunications network, there is spare capacity waste due to spare capacity dimensioning for the spare capacity reserved for higher layer's restoration route. This problem is solved clearly using mapping functions among layers and clear traffic differentiation between multiplexed and injected traffic in spare capacity dimensioning. We define two sharing methods, which are called horizontal and vertical sharings, to solve the unclear spare capacity dimensioning problem. The design proposed in this dissertation achieves spare capacity reduction and robust survivability operation for a multilayer telecommunications network. In the experiments section, a heuristic optimization method instead of IP is used to have a near optimal solution due to the increase of problem size in optimization, by considering multiple layer dimensioning as a single problem. Tabu search provides a decent quality solution within reasonable time for a large problem.