Design and analysis of survivable multipath provisioning in telecom mesh networks.

摘要

The explosive growth of bandwidth-intensive applications is creating a huge demand for bandwidth. Optical networks employing wavelength-division-multiplexing (WDM) technology have emerged as the most viable infrastructure for wide-area telecom backbone networks because of their tremendous capacity. Today, network operators and service providers face an increasing number of challenges in addressing customer demands for new services while continuing to deliver traditional voice and private line service. New services such as Ethernet and storage-area networks can not be efficiently delivered over legacy SONET/SDH networks. However, the maturity of next-generation SONET/SDH and WDM technologies can transform this infrastructure to make it both an efficient and flexible transport network to meet the demands. Survivability is a critical concern in such networks because the failure of a network element may cause tremendous data (on the order of terabits per second) and revenue loss.;Telecommunication networks spanning large areas are subject to various failures, such as natural disasters, operation errors, and malicious attacks. Disaster Failures (DF) are defined as failures which can lead to a large-area malfunction of a network, and which can significantly degrade the performance of backbone telecom mesh networks. A survivable network provisioning scheme that can differentially recognize and address multiple levels of network failures, including disaster failures, is desirable for the future Internet.;Multipath provisioning, supported by virtual concatenation (VCAT), is a key feature of next-generation SONET/SDH-over-WDM networks, and it can significantly outperform single-path provisioning in resource efficiency, service resilience, and flexibility. This research investigates the design and performance analysis of survivable multipath provisioning in next-generation telecom networks.;This dissertation introduces the background technologies in Chapter 1. Chapter 2 studies survivable multipath provisioning with differential-delay constraint (DDC) in telecom mesh networks. We propose Shared Protection of the Largest Individual Traversed link (SPLIT) method for survivable multipath provisioning, and present a DDC-based algorithm for multipath routing. Simulation results show that the DDC-based algorithm is an efficient, low-complexity, and fast-fault-recovery algorithm for typical backbone networks.;The problem of adaptive reliable provisioning in next-generation backbone mesh networks employing WDM and supporting VCAT is investigated next in Chapter 3. We develop an analytical model for connection availability under multipath provisioning schemes. Two types of bandwidth-migration methods and heuristic algorithms for availability-guaranteed provisioning are proposed and studied. The bandwidth-migration methods can be implemented by link-capacity adjustment scheme (LCAS) protocol of next-generation SONET/SDH to optimize resource usage. We show that, for end-to-end connection-availability-guaranteed service, multipath provisioning can achieve better network performance than traditional single-path provisioning. With bandwidth migration, we can further improve multipath provisioning performance.;In Chapter 4, we investigate the survivable traffic grooming problem with inverse multiplexing in next-generation SONET/SDH networks employing WDM. With support of VCAT, a connection of any bandwidth can be provisioned as several sub-connections (i.e., inverse-multiplexed) over diverse paths. How to efficiently protect and groom these low-speed sub-connections onto high-capacity wavelength channel, considering the typical constraints, is an important and interesting problem. We propose and investigate the characteristics of survivable multipath traffic grooming with connection and lightpath level protection in telecom mesh networks. We study the multipath provisioning with protection-at-connection (MP-PAC) level, protection-at-lightpath (MP-PAL) level for grooming a connection request with shared protection, subject to the constraints of inverse-multiplexing factor (IMF), differential-delay constraint (DDC), and grooming ports. Since a special case of this problem (IMF = 1, DDC = infinity) is NP -complete, we propose effective heuristics with a novel analysis model.;In Chapter 5, we study the characteristics of multiple failures in telecom mesh networks, such as optical WDM networks. In particular, we devise a novel provisioning scheme for telecom mesh networks, which can efficiently exploit the network connectivity using multiple paths. Three provisioning states are defined, in response to single-link failure (SF), multiple-link failure (MF), and disaster failure (DF). We integrate the conventional primary-backup method with reprovisioning and degraded service (i.e., a reduced level of service vs. no service at all) into a state-transition model to handle different levels of failures. A pre-defined level of service is guaranteed for premium customers even if the service cannot be fully recovered. Multi-node failures within the same Shared Risk Group (SRG) and failures on destination node are also considered for completeness of our study.;Chapter 6 concludes the dissertation with a summary of our contributions. Multipath provisioning not only brings lots of benefits such as better load balance, lower blocking rate, etc., but also offers flexibility and resilience for network survivability. This dissertation studies multipath routing and provisioning in different contexts. Thus, it makes important contributions by investigating the benefits and issues behind the deployment of next-generation SONET/SDH technologies in modern telecom networks.