Multicast routing with QoS constraints

As it was originally designed, the Internet or an IP-based network in general provides “best-effort” service which doesn't guarantee timely or actual delivery of data packets. While many traditional datagram applications still work well despite the unpredictability in service quality, predictable and controllable service quality is a necessity to effectively support emerging real-time applications for which there are growing interest and demand. Meanwhile, as the Internet evolves into a global commercial infrastructure, QoS support must become an integrated part of it. QoS provisioning involves almost all elements in a network system. One key component for QoS support is constraint-based routing, or the so-called QoS routing which can enable more effective and efficient QoS support by allowing dynamic route selection based on network resource availability and QoS requirements. IP multicast utilizes a tree structure to deliver data, and the new challenge imposed by QoS support is how to build multicast trees subject to QoS constraints.; This dissertation proposes and studies algorithms and strategies for QoS-constrained multicast routing. First we introduce an algebraic notation for QoS metrics, which not only simplifies problem formulation and solution presentation, but also helps us in developing our solutions. We also propose a family of “smart-forwarding”-based algorithms which enable fast, table-driven computation of QoS-constrained routes. We then propose a comprehensive set of algorithms and strategies for multicast. For single-source one-to-many type of multicast applications, we propose a receiver initiated joining mechanism to construct QoS-feasible multicast trees dynamically and incrementally. For many-to-many type of applications, we propose an algorithm to build bi-directional shared-trees. For inter-domain shared-tree QoS multicast, we propose a QoS information propagation mechanism and an alternative join point search strategy to address some limitations and the excessive overhead drawback of existing flooding-based strategies. For fast restoration of multicast connections in face of network node or link failure required by some applications, we propose a scheme based on a “dual-tree” structure in which a secondary tree for fault-tolerance purpose is built as a complement to the primary multicast tree. We conduct simulation studies to evaluate our algorithms and strategies and compare with other similar or related approaches, and we see improved or comparable performance in most cases.