基于双向令牌的可扩展及可靠的群组成员管理

面向有线因特网的群组通信已研究多年,目前仍是研究热点之一,尤其是将现有研究成果扩展到移动与无线网络环境方面.研究了移动群组通信,该问题涉及群组成员关系动态性(成员加入及退出)、成员位置动态性(移动主机的移动性)和网络动态性(结点或链路出错).提出了适合于移动群组通信的基于双向令牌的层次环模型(也称为层次环结构)以解决该问题.该模型是逻辑环与逻辑树的结合模型,它利用了逻辑环的简单性和逻辑树的可扩展性.更为重要的是,这样的结合使得基于层次环结构的群组通信协议比现有的基于树结构的协议更可靠.理论分析和模拟研究表明:(1)当群组规模增大时,该协议的可扩展性很好;(2)该协议具有很高的可靠性.该协议特别适合于服务提供者和网络运营商将其计算设备分层次部署的情况,这时就要求每台计算设备都能局部化地维护其兄弟和父亲设备的信息.

Scalable and Reliable Group Membership Management with Bi-Directional Tokens

Group communications have been studied in the wired Internet for many years and remain a very hot research topic,especially on extending the existing achievements into mobile and wireless network environment. This paper identifies some interesting problems in mobile group communications regarding dynamic group membership due to member joining and leaving,dynamic locations due to node mobility,and dynamic networks due to node/link failures.These problems are solved by proposing a ring-based hierarchy of proxies with bi-directional tokens.The proposed hierarchy is a combination of logical rings and logical trees,which takes advantage of the simplicity of logical rings and the scalability of logical trees.More importantly,such a combination makes the proposed protocol based on this hierarchy more reliable than the existing tree-based protocols.Theoretical analysis and simulation studies of the proposed protocol show that:(1)It scales very well when the size of a group becomes large;(2)It is strongly resilient to failures that occur in the network.It is particularly suitable for those service providers and network operators which have deployed their machines in a hierarchical setting,where each machine can be locally configured to know the information about its sibling and parent machines.