Integrated mechanisms for QoS and restoration in mesh transport networks.

摘要

Survivable networks have the capability to survive from the events of network components failures. The resilience mechanisms in these networks protect and restore the impaired communication paths by using spare capacity. On the other hand, Quality of Service (QoS) mechanisms focus on network capabilities that provide the facilities to differentiate network traffic and offer different levels of service to each class of traffic. Traditionally the survivability algorithms were applied at the physical (optical) layer, whereas the QoS mechanisms mainly applied at packet-forwarding level. Recent technological breakthroughs can now facilitate novel forwarding techniques for optical data bursts that make it possible to capture packets at the optical layer. A major challenge in the transfer of these ultrahigh-speed data bursts is to allocate resources according to QoS specifications and to provide spare capacity required to address link failures. Consequently, development of novel integrated strategies that facilitate implementation of QoS and survivability algorithms is of significant practical interest and is the primary focus of this study.;We present three novel mesh restoration techniques aimed at minimizing simultaneously the packet delay time and the restoration capacity in transport networks. These algorithms are: Two-step Delay-Constrained Pool Sharing (TDPS), Hybrid Pool Sharing (HPS), and One-Step Delay-Constrained Pool Sharing (ODDS). We show that how these schemes can be used to yield low end-to-end delay paths for demands in the network while still minimizing the spare capacity. Using simulation methodology, we evaluate the performance of all of these algorithms and compare them with representative existing restoration/QoS algorithms.;We also present three novel integrated routing techniques aimed at minimizing the use of restoration capacity and enhancing the traffic load balancing in mesh transport networks. First, we present a Load Balancing Pool Sharing (LBPS) scheme and show how this scheme can be used to balance the loads on the network links while still minimizing the restoration capacity in the network. In order to eliminate the so called trap-topology problem, we introduce two new heuristic algorithms, called Iterative Simple Pool Sharing (ISPS) and Iterative Load Balancing Pool Sharing (ILBPS). We compare the capacity-usage, load balancing, and computation complexity performances of the LBPS and ILBPS algorithms with some representative algorithms, and we show that the proposed schemes can similarly or more evenly distribute the network traffic among network links than the other schemes at lower computation cost.