LEDBAT协议优先级反转抑制的启发式动态阈值算法  

HDT:A Heuristic Dynamic Threshold Algorithm to Avoid Reprioritization of LEDBAT

作　　者：马阿曼 江先亮[1] 金光[1] Ma Aman;Jiang Xianliang;Jin Guang(Faculty of Electrical Engineering and Computer Science,Ningbo University,Ningbo,Zhejiang 315211)

机构地区：[1]宁波大学信息科学与工程学院,浙江宁波315211

出　　处：《计算机研究与发展》2020年第6期1292-1301,共10页Journal of Computer Research and Development

基　　金：国家自然科学基金项目(61601252);浙江省公益技术研究项目(LGG18F020007);宁波市自然科学基金项目(2017A610116)。

摘　　要：近年来,随着通信技术和网络传输能力的大幅度提升,应用需求呈现多元化的增长态势(视频会议、在线游戏等交互式应用要求低时延、低抖动,而软件更新等应用则要求高吞吐).为满足时延不敏感的数据传输并保证高效的瓶颈带宽利用率,低优先级拥塞控制算法(如LEDBAT(low extra delay background transport))受到广泛关注.该类算法能在链路空闲时占用未被使用的带宽,而在链路负载较高时释放占用的带宽以保证时延敏感数据的传输.然而,当中间路由器部署主动队列管理算法时,低优先级拥塞控制算法存在优先级反转问题,即链路高负载时无法释放占用的带宽,使其退化为普通拥塞控制算法.为解决该问题,针对LEDBAT中的固定时延阈值造成的优先级反转,提出启发式的动态阈值调整算法,其在运行时动态搜索最优的动态时延阈值,确保LEDBAT与主动队列管理算法共存时仍能保持低优先级特性,同时不降低链路的利用率.为验证算法的有效性,在网络模拟NS2中建立了不同网络场景并对算法进行大量的评估.实验结果表明:与已有低优先拥塞控制算法相比,新算法能够有效解决优先级反转的问题,同时保证链路的带宽利用率.In recent years,with the significant increase in communication technologies and network transmission capabilities,the requirements of applications have shown a diversified growth trend(such as video conferencing and online games with low latency,low delay jitter and software updates with high throughputs).In order to meet delay-insensitive data transmission and ensure efficient bottleneck bandwidth utilization,low priority congestion control(LPCC)algorithms such as LEDBAT(low extra delay background transport)have received increasing attention.These algorithms can occupy available bandwidth when the link is idle,and release the occupied bandwidth when the link load is high to ensure the transmission of delay-sensitive data.However,when AQM(active queue management)is deployed on the router,the reprioritization problem of LPCC occurs.When the link is under heavy load,the occupied bandwidth cannot be released by LPCC,which degenerates into an ordinary congestion control algorithm.To solve the problem,this paper proposes a heuristic dynamic threshold adjustment algorithm,called HDT which can dynamically search for the optimal dynamic delay threshold,ensuring it maintains low priority while coexisting with AQM without reducing link utilization.We establish different network scenarios in the network simulator NS2 to verify the effectiveness of the proposed algorithm.The results show that HDT can effectively solve the problem of reprioritization while ensuring the bandwidth utilization of the link.

关 键 词：拥塞控制算法 LEDBAT算法 主动队列管理 优先级重置 启发式动态阈值 

分 类 号：TP393[自动化与计算机技术—计算机应用技术]