Overlay Network Organizational Structure And Its Qos Routing

Overlay network is a virtual network which constructs a user level graph on top of an existing networking infrastructure such as the Internet, it is a user-level topology built by selecting a subset of the nodes in the underlying network and connecting them by virtual links. It can easily be employed and provide much better quality of service without requiring changes of standards and without the risks associated with experimentation on an operational network infrastructure. Spines is an open source overlay network system that allows easy deployment and testing of overlay protocols, which employs hop-by-hop reliability techniques considerably reduces the average latency and jitter of reliable communication. It supports real-time multi-media service which requires good QoS, and can be easily applied to development and test of network protocol.Self-organization on overlay network is the focus of this thesis. After introduces the two-level hierarchy, software architecture, main protocol and the functionality they supported of Spines, this thesis introduces the implementation of the Spines simulation platform on NS2, and propose an self-organizing architecture on Spines by adopting the DHT technology of P2P which allows nodes join and leave network easily. This architecture greatly improve the robust and scalability of Spines. The theoretical analysis and simulation results show that it can adapt the dynamic topology and find right path for transmission and achieve good performance of self-organization with a little overhead. Then, we present the bandwidth-based dynamic QoS routing algorithm (BDQR) about Spines self-organization architecture. In this algorithm, we consider several metrics such as available bandwidth, the computation capacity of node and delay. The optimal network path can be selected between two nodes with the cost of path computed. By simulation and contrast with other algorithms, BDQR has a better QoS-satisfied rate and operates well in balancing the network resources. It also obtains good performance in transmission, and can realize hop-by-hop reliable and real-time communication in dynamic overlay network.