等价多路径间基于LRU Cache和计数统计的流量分配调度算法  

Achieving Optimized Traffic Sharing over Equal-Cost-Multi-Paths Using LRU-based Caching with Counting Scheme

作　　者：林伟[1,2] 刘斌[3] 唐毅[3] 

机构地区：[1]清华大学深圳研究生院,广东深圳518055 [2]香港城市大学,中国香港 [3]清华大学计算机科学与技术系,北京100084

出　　处：《电子学报》2008年第1期32-38,共7页Acta Electronica Sinica

基　　金：国家自然科学基金(No.60373007,60573121);中国-爱尔兰科学技术合作研究基金(No.CI-2003-02);高等学校博士点基金(No.20040003048);清华大学985基金(No.JCpy2005054)

摘　　要：为了减少网络拥塞并充分利用链路带宽,当在转发节点与目的子网间存在有多条等价路径(ECMPs)时,流量负载应该在ECMPs间均衡分配,并且属于同一个TCP流的IP分组应该按照相同顺序到达目的主机.本文提出了一种基于LRU(Least Recently Used Algorithm)Cache和计数统计的算法.该算法通过为每条ECMP分配一个计数器,利用计数统计从而考虑到了IP分组的长度差异.使用相对计数以及对某些情况增加约束条件解决了计数器溢出问题.UDP分组只需要作为调节负载均衡的流量.更进一步,对于去往同一目的子网的不同主机的TCP流的时延差异被转化为cache中的表项失效的时间长度差.仿真实验表明,当ECMPs间的时延差不显著的情况下,只需要很小的存储空间,且每次cache查找只需要一个时钟周期,负载均衡接近最优,此时只有2%的分组出现乱序.In order to reduce network congestion and fully use link bandwidth, when there are Equal-cost-multi-paths （ECMPs） between a forwarding node and a destination subnet, traffic load should be balanced among ECMPs and packets of the same TCP flow should reach destination host in the same order. An algorithm called LRU-based caching with counting （LCC） is proposed. Packet length differentiation is considered to achieve load balance by adapting a counter for each ECMP, and counter overflow is solved by relative counting and restrictions. UDP packets only need to be concemed to achieve load balance. Furthermore,flow delay differentiation forwarding to different hosts of the same destination subnet is transformed to entries in cache invalided time period difference. Simulation shows that when delay differentiation among ECMPs is not significant, storage requirement is small,only one cycle is needed for each cache lookup,load balance is near optimal,and only 2% of packets are out of order.

关 键 词：流量分配 等价多路径 LRU CACHE 计数统计 

分 类 号：TP393.05[自动化与计算机技术—计算机应用技术]