AACP:可靠多播网络中的自适应主动缓存管理协议

Adaptiveand Active Cache Pool in Reliable Multicast

缓存管理是影响可靠多播协议性能的重要因素。在可靠多播领域,现有大多数缓存管理机制的设计目标限于单多播组的网络环境。在缓存资源被多个多播组所共享的Internet环境中采用单组缓存管理方案无法获得预期目标。为了解决该问题,基于主动式网络中路由器能够执行预设计算并缓存数据的特点,提出并实现了一种全新的多播网络缓存管理协议(Adaptive and Active Cache Pool,简称AACP)。AACP提出全局动态分配,Borrow-In和Return3种核心策略,首次提出采用全局加权移动平均计算缓存配额,并设计出分级TTL缓存替换算法。NS2模拟实验的结果数据表明,AACP能为多播网络在恢复延迟,带宽消耗和网络吞吐等方面带来显著的性能提升。这同时也意味着AACP将为对数据完整性和实时性要求极高的多播应用,如金融电子化实时系统和电子白板等,提供高质量的基础支撑。

In order to solve the problem of how to share buffer resources for several simultaneous ongoing multicast groups, based on the fact that active router in active network can perform customized computation and provide soft- stage storage, a novel buffer management scheme, called Adaptive and Active Cache Pool （AACP）, for large-scale multicast network was proposed. AACP consisted of three adaptive policies--Global Dynamic Buffer Partitioning Policy, Borrow-In Policy and Return Policy. Global EWMA allocation algorithm and multi-level TTL buffer replacement algorithm were also proposed. Simulation results showed that AACP outperformed other existing reliable multicast protocol in reducing recovery latency and bandwidth consumption, and rasing network throughput. It also meant that AACP could provide high quality supporting foundation for completeness-sensitive and time-sensitive multicast application, such as e-trade system and whiteboard etc.