一种基于树树结构的低时延应用层组播模型

摘要

As an alternative of IP multicast,application layer multicast is widely used with the advantage of simplicity and flexibility,but the disadvantage of large transmission delay affects the performance.In this article,to reduce the transmission delay in large-scale application layer multicast,a hierarchical tree-tree model is proposed.This model organizes and manages multicast group members using two-tier structure,and considers the nodes capability and the delay between nodes in building low delay multicast tree.When nodes join or leave the multicast group,multicast tree maintenance algorithm is designed to keep small delay variation,and meet the low delay requirement.The computer simulations prove that this model reduces the application layer multicast transmission delay effectively,improves the application layer multicast performance,and therefore it is suitable to apply in large-scale real-time multimedia environment.%作为IP组播的替代,应用层组播具有简单灵活的优势,获得了广泛应用,但时延较大的缺点对性能影响较大.针对大规模应用层组播时延较大的问题,提出一种层次化的树树组播模型来降低应用层组播时延,该模型利用两层结构来组织和管理应用层组播组成员,并考虑节点性能和节点间时延来构建较低时延的组播树.当节点加入或退出组播组时,设计合适的组播树维护算法使得组播树的时延变化较小,满足低时延要求.计算机仿真表明该树树组播模型能够有效降低应用层组播的时延,改善大规模应用层组播性能,适合应用在大规模实时多媒体环境中.