Design of reliable network architectures and algorithms.

摘要

Fiber optics employing wavelength-division multiplexing (WDM) is a technology that can meet our explosive growth for bandwidth demand. With WDM, the huge bandwidth of an optical fiber can be partitioned into many non-overlapping wavelength channels, each of which can operate at the data rate of 10 Gbps (or 40 Gbps or higher). In the high data-rate network, a network element failure may cause tremendous data traffic loss. Even in the absence of network failures, with increasing data rate, the transmission impairments in the physical layer become more troublesome for signal-quality degradation, which affect the quality of network services. For high quality of service (QoS) in today's networks, reliability is a critical concern in network design. This dissertation investigates architectures and routing algorithms for a reliable optical Internet.;The dissertation first investigates intelligent routing algorithms which are impairment aware to efficiently provide signal-quality-guaranteed connections in a WDM network. To ensure service quality of high-speed connections, we develop a hierarchical routing-and-wavelength-assignment model where signal quality of a data path is estimated in the physical layer, and regarded as an important metric for route computation in the network layer.;Next, the dissertation investigates fault-management strategies for combating network failures in a wavelength-routed network. A new link-state modeling mechanism is developed to form a dynamic link-state parameter which represents both physical-layer availability and resource status of an optical link. Based on the link-state availability model, a generalized protection framework is proposed to guarantee customers' availability requirements.;The reliability issue is also studied for packet-switched networks (i.e., optical burst-switched networks). First, a switching-node architecture using waveband-selective switching is proposed. A new data-transmission scheme is designed to incorporate the proposed waveband switching, and the routing property of the switch architecture is designed to reduce data-burst loss probability. Second, with the burst-switching technique, we develop dynamic routing mechanisms for preplanned congestion avoidance. Two update mechanisms for maintaining a dynamic routing table are proposed to accommodate bursty data traffic. Based on such routing mechanisms, we develop a novel protection approach which employs a primary route and a group of backup routes for each node pair against network failures.