自组网按需路由协议中路由缓存生存期的研究

Research of route-cache lifetime on performance of on-demand routing protocols in mobile Ad Hoc networks

在自组网按需路由协议中,为了避免为每一个数据包重复引发路由发现过程,需要对路由条目进行缓存。路由缓存的生存期(TTL)对协议性能有着重要的影响。通过大量的基于ns-2的仿真实验详细分析了在不同的自组网环境下路由缓存生存期对按需路由协议性能的影响,包括端到端延迟、传输成功率和协议控制开销等,对TTL值设置过小导致的路由缓存条目删除过早和TTL值设置过大导致的删除过迟等的影响进行了讨论,分析了不同网络场景下最优路由缓存生存期的可能取值,为动态调整路由缓存生存期提供了依据。

In on-demand muting protocols for mobile ad hoc networks, available routes are usually cached to reduce path discovery as much as possible. The route cache lifetime setting is critical to the on-demand ad-hoc routing protocol performance. Through extensive simulations under ns-2, the impact of different route cache TTL setting on the routing performance in different scenarios is investigated. The effects of early-deletion due to smaller TTL setting and late-deletion caused by larger TTL setting on the routing performance in terms of packet delivery ratio, normalized routing overhead and average end-to-end delay are presented and analyzed. Clues for dynamic tuning of TTL setting are provided.