The Research About Optimizing And Constructing Multi-domain Clustering Topology-Aware Application Layer Multicast Tree

With rapid development of the Internet, communication and network technology advances and has penetrated into many aspects of society. They had a profound impact on people’s lives, study and work. Earthshaking development of Internet technology has lead to the result that the text and image-based Internet applications cannot satisfy people’s needs any more. At the same time, the Internet’s most popular application of the first-class media service is developing rapidly. Therefore, the traditional unicast technology cannot meet the needs of users’requirement of the streaming media, so new multicast technology is introduced to this field. But the IP Multicast routers needs support in the Internet infrastructure and adding new routing and forwarding mechanism based on the network layer. That is the reason why it cannot be widely used on the Internet until now.The appearance of ALM not only retains the advantages but also makes up for the shortage of IP multicast, which contributes to the rapid development of the Internet. In the application layer multicast overlay networks, multicast members are composed by a unicast connection and end-host is responsible for routing associated with the multicast group membership management, copying and forwarding packets and other functions. Although the application layer multicast can effectively reduce the load pressure on the server, it will increase the client’s transmission delay and reduce the client’s user experience. The application-layer multicast also face practical problems as follows:(1) due to the client’s ignorance of the underlying topology of the network, the nodes may be distributed in a similar multicast forwarding tree distant location, resulting the degradation of the multicast performance; (2) adding of the group members is a gradual process, new entrants relies on existing information to determine its own node in the multicast forwarding tree position to a large extent. In other words, different addition order will have a direct impact on the multicast forwarding tree structure and performance. Therefore, the key point to solve the above problem is to build an efficient application layer multicast tree.In order to improve the stability and efficiency of the application layer multicast tree, this thesis proposes a multi-domain-based domain-aware application layer multicast clustering algorithm Multi-Dom CTA (Multi-domain Clustering Topology-Aware Application Layer Multicast). Multi-Dom CTA Firstly nodes are organized according to the transmission delay of the link will be similar in a topological domain, in order to achieve the nearest transport packet. Experimental results show that, Multi-Dom CTA model has good clustering performance, and achieve optimal clustering radius experimentally selected domain multicast performance. Then according to the node bandwidth and node uptime dynamically adjust topology, effectively reducing the order of the different nodes join the multicast forwarding tree adverse effects. Experimental results show that, Multi-Dom CTA model has good convergence and reduce the depth of the multicast forwarding tree, effectively reducing the multicast forwarding tree average delay and control the maximum delay of growth. Finally, through the Multi-Dom CTA model of maintenance, you can quickly find the abnormal state of multicast forwarding tree and quickly restore multicast forwarding tree, thus ensuring the normal multicast Multi-Dom CTA model.Finally, the paper summarizes the model, a clear advantage and identify deficiencies, and to explore the direction of future research and improvement.