中文摘要：

组播是一种高效的多点通信方式，IP组播效率高，但需专门的组播路由器，代价大，至今未能大规模部署．应用层组播数据的复制转发功能由终端主机完成，不涉及现有网络基础设施的更新，在Internet上容易实现，但终端主机的稳定性和安全性不如组播路由器，容易导致单点失效，且数据恢复困难．为解决应用层组播存在的可靠性问题，提出了一种树环结构的应用层组播方案，通过环结构来增加数据传输的可靠性，并采用主动随机转发技术来解决树环结构的多点失效问题．该方案既有效解决了应用层组播可靠传输问题，又降低了恢复时延和系统开销．

英文摘要：

Muhicast is an efficient way for one-to-many communication. IP muhicast is efficient, but because of its high cost, it has not been in large scale deployed. Application layer muhicast with end-hosts to deal with data duplication and transmission does not need to do any modification on present network infrastructure, so can be easily employed in the Intemet. But compared with muhicast touters end-hosts have their own disadvantages such as in stability and security. It is easy to cause failure in single-point and difficult to recover data . A tree-ring based structure for application layer muhicast to solve these problems was introduced. The structure improves the reliability of data transmission greatly. It uses proactively randomized forwarding technology to overcome tree-ring based structure muhipoint failure problem. The scheme improves the overhead and the latency of recovery. reliability of data transmission, and reduces system