Abstract: This paper proposes LCcast，a novel scheme based on NICE，which gives P2P application-layer for multicast.It uses the hierarchical clustering structure，and makes the powerful leader nodes from all the clusters organized by the Chord in the result of extracting an implicit multicast tree easily.It uses the finger table defined in the Chord and the Dijkstra algorithm to establish the minimum delay multicast tree，and chooses a number of backup leader nodes in the cluster to form a stack in order to prevent the packet loss.Simulation results indicate that the scheme can improve the data transmission rate and reduce the control overhead and the load of the leader node.

Key words: NICE, application-layer multicast, LCcast

摘要： 在对NICE应用层组播协议研究的基础上，提出了一种新的应用层组播方案LCcast。它采取分层分簇的结构特征，从簇中选择出能力强的领导节点用Chord环组织起来。在数据传输方面，使用Chord环中定义的指向表并结合Dijkstra算法生成最小延迟的组播树，从而减少了传输延迟。同时，为了防止数据包丢失，对每一个簇选择了一个备用领导节点集合。仿真结果表明，LCcast组播方案在一定程度上减少了时间延迟，提高了平均数据传输率，降低了控制开销和领导节点的负载。

关键词: NICE, 应用层组播, LCcast