Research On Application Layer Multicast Tree Construction Strategy And Recovery Strategy Based On NICE Protocol

With the rapid development of Internet and information technology,people's demand for real-time information acquisition is increasing,and a large number of applications of real-time media services have emerged.A large number of user groups make the traditional unicast mode can not meet the transmission requirements of these application.In order to avoid the low efficiency and waste of bandwidth of unicast,the IP multicast is proposed.However,the need to change the underlying structure of the existing network in the deployment of IP multicast.So IP multicast has not been able to get large-scale application.Aiming at the disadvantage of IP multicast,application layer multicast is proposed,Application layer multicast complete the replication and forwarding of streaming media by client that participating in the multicast,with the advantages of easy deployment,good scalability and support large multicast group.Application layer multicast system copy and forward source data depends on the participation of the client.However the client instability is the natural weakness.The stability of the application layer multicast system is closely related to the client's exit and failure.How to establish a stable application layer multicast system and how to shorten the recovery time of the application layer multicast system after the node exit is the key and difficult point in the application layer multicast system.In view of the above two points,this paper puts forward:1,Construction strategy of multicast tree for node rejoin based on NICE protocol.The next online time of the node is predicted by recording the time of the node in the multicast tree.In the construction of multicast tree.The node is added to the multicast tree by preferential strategy.The simulation results show that the multicast tree constructed by this method has obvious advantages in stability.2,Recovery strategy of multicast tree for query recovery table.Create a recovery table by passing a node with an incomplete degree.Node query recovery table for its child node.to find a new parent node when it exits,the nodes in the recovery table is not full degree.When searching for the parent node,the flooding search is avoided,and the recovery time of the multicast tree is greatly reduced.Also,the fesibility and superiority of this strategy are verified by simulation expriments.