Research On Quality Of Service Mechanisms For Hierarchically Switched Networks

With the explosive growth of its scale and the continuous evolving to supporting integrated services, the Internet encounters some problems that have not ever been anticipated at its beginning. In order to satisfy the requirements of the future networks, the architecture of the Internet needs some essential reformation. Therefore, Professor Qian Hualin put forward the idea of Hierarchically Switched Networks (HSNet). HSNet introduces hierarchy into network topology and the address structure, and establishes a one-to-one mapping between the network topology and the address structure. HSNet provides advantageous properties for Quality of Service (QoS) control. This dissertation addresses the mechanisms of QoS control for HSNet.A QoS control model for HSNet is brought forward in this dissertation. By combining the advantages of HSNet with the DiffServ model, the QoS model for HSNet is scalable and easy to implement. Before a traffic flow can send packets into the network, it should reserve resource along the path using signal, so the network can guarantee there is enough resource to satisfy the requirements of the flow along the path. Therefore, QoS control of HSNet strengthens the service guarantees of DiffServ model. The QoS model for HSNet includes three sorts of service: virtual leased line, assured forwarding and best effort. Virtual leased line is intended to provide a building block for low delay, low jitter and low loss services by ensuring that the virtual leased line aggregate is served at a certain configured rate. For assured forwarding service, the system guarantees that the flow can achieve some amount of service even during the period of network congestion. The best effort service is the same thing as that of the traditional Internet and the system does not guarantee anything.A resource management scheme for HSNet is discussed in the dissertation. Each domain has a resource management server which takes charge of managing the bandwidth of every logic link of a domain in a fashion of centralization. As to the whole HSNet, the resource management task is performed with cooperation of servers settled in each domain. The server maintains states for aggregate flow instead of individual flow. The combination of centralization with distribution and the resource management in unit of traffic class instead of individual flow can assure the scalability and reliability of resource management system. At the same time, the separation of controlling from switching is of benefit to implementing of switches in the context of high speed networking.Resource allocation and management schemes are discussed in this dissertation. For virtual leased line traffic, the node allocates bandwidth according to the flow's peak rate. For assured forwarding traffic, the node allocates bandwidth according to the flow's average rate. In order to resolve the problem of resource hiding due to various reasons such as signal...