Optimization Of Structure For Application Layer Multicast And Its Fault-and Intrusion-Tolerant Scheme

Multicast that can save network resources and improve the network efficiency is a group communication model of data transmission among many points. Multicast is a critical and supporting technique for next generation Internet applications such as video conference, content distribution, games and simulation system. Recently IP multicast has not been applied widely for its limitations like group member management, scalability and network deployment. Application Layer Multicast (ALM) emerges as the time requires, ALM can provide multicast service without changing existing network infrastructure. The basic idea of ALM is to organize the member nodes into an overlay network, on which data distribution tree is built directly. ALM implements multicast function like group member management, message replication and content distribution at end hosts.Topology management is very important in ALM architecture. Many researchers have studied the maintenance and optimization of topology structure without optimization scheme during the topology construction procedure. The non-leaf nodes in the multicast tree play a critical role in ALM architecture. The departure or failure of non-leaf nodes will affect all downstream nodes. A fault-tolerant mechanism should be considered to recover the affected nodes from partitioned tree automatically and make them rejoin the multicast group communication quickly. The non-leaf nodes are prone to be attacked in ALM, an intrusion-tolerant scheme should be considered to avoid the failure of one node, which will affect the normal running of the multicast tree. Recently intrusion-tolerant technology has not been used in ALM system.The research works of this thesis are optimization of tree management protocol and fault- and intrusion- tolerant scheme based on ALM. The major research works of this thesis are listed as follows:Firstly, YTMP (Yoid Tree Management Protocol) of Yoid is selected as research foundation, whose tree building process is optimized by appending"distance proximity"algorithm. It improves the network transmission efficiency as well as the stability of the topology structure. This idea can also be applied in other ALM schemes.Secondly, an improved cooperative failure detection mechanism and a corresponding reliable failure recovery scheme are proposed to achieve high reliable fault-tolerant mechanism based on analysis of related works.Thirdly, a corresponding intrusion-tolerant scheme is proposed to ensure the consecutive service of the system.Finally, optimization scheme of tree construction is implemented by C code.