Design And Analysis Of Survivable Wdm Mesh Networks

In this thesis, we are particularly interested in studying the impact of network element failure(s) on network survivability. Namely, we propose and analyze a series of models and schemes to protect and restore the affected services in the networks, thus achieve a better survivability in optical networks. In additions to an introduction of optical networks and a survey of the related work, this thesis first focuses on the problem of fast recovery in Chapter 3. By using the framework of Offset-Time restoration, a novel model based on time-driven scheduling is proposed. It substantially shortens the restoration time and can be applied in both single-link failure and dual-link failure scenarios. Next, capacity reprovisioning, as a simple and efficient mechanism to protect a network against multiple failures, is investigated and a new reprovisioning scheme is proposed in Chapter 4. Finally, the application of capacity reprovisioning in traffic grooming is considered. Two frameworks, i.e., lightpath level reprovisioning and connection level reprovisioning, are proposed in Chapter 5 to improve the survivability of optical networks with grooming capability.

Covers these key topics: Shared-mesh protection for optical WDM networks. Survivable traffic grooming for hierarchical optical WDM networks. Survivable data over next-generation SONET/SDH with inverse multiplexing.

This dissertation addresses several important survivable design issues in WDM mesh networks. Shared backup path protection has been shown to be efficient in terms of capacity utilization, due to the sharing of backup capacity. However, sharing of backup capacity also complicates the restoration process, and leads to slow recovery. The p-cycle scheme is the most efficient ring-type protection method in terms of capacity utilization. Recently, the concept of pre-cross-connected protection was proposed to increase the recovery speed of shared path protection. We overview these protection methods. The recovery time of these schemes are compared analytically. We formulate integer programming optimization problems for three protection methods in static traffic scenario, considering wavelength continuity constraint. We develop a p-cycle based scheme to deal with dynamic traffic in WDM networks. We use a two-step approach. In first step, we find a set of p-cycles to cover the network and reserve enough capacity in p-cycles. In second step, we route the requests as they randomly arrive one by one. We propose two routing algorithms. Compared to the shared path protection, the p-cycle based design has the advantage of fast recovery, less control signaling, less dynamic state information to be maintained. To evaluate the blocking performance of proposed method, we compare it with shared backup path protection by extensive simulations. We propose a path-based protection method for two-link failures in mesh optical networks. We identify the scenarios where the backup paths can share their wavelengths without violating 100% restoration guarantee (backup multiplexing). We use integer linear programming to optimize the total capacity requirement for both dedicated- and shared-path protection schemes. The recently proposed light trail architecture offers a promising candidate for carrying IP centric traffic over optical networks. The survivable design is a critical part of the integral process of network design and operation. We propose and compare two protection schemes. The survivable light trail design problem using connection based protection model is solved using a two-step approach.