面向网络行为的CDN缓存分配策略

Network Behavior-oriented CDN Cache Allocation Strategy

撒谎行为的存在会破坏CDN缓存分配的公平性。使用博弈论对服务器在缓存分配过程中的自私撒谎行为进行了研究。经分析发现,服务器撒谎行为的本质就是当缓存不足时,额外多申请一定量缓存;而当缓存充足时,则诚实地申请所需缓存量。针对这种撒谎行为,提出了一种公平分配算法,在计算服务器的缓存申请量时,考虑其历史缓存申请量,并根据不同阶段申请量的有效性不同引入年龄因子,(重新)计算得到服务器的当前有效缓存申请量,使得撒谎的服务器与诚实的服务器相比受到更多损失,以此来促使其停止撒谎行为。同时,公平算法还保证了系统的最大吞吐量,并引入了价格机制来保证诚实的服务器得到更高的需求满足度。仿真实验结果表明,公平算法对于上述撒谎行为有很好的改善效果。

Lying behavior may destroy the fairness of CDN cache allocation.The selfish lying behavior of servers during CDN cache allocation with the game theory was studied.The essence of lying behavior is that servers will apply more cache when the total cache is not enough,otherwise honestly apply requisite cache volume when the total cache is enough.We proposed fairness algorithm to deal with lying behaviors.We considered the historical application volume while calculating the new one.In addition,we introduced the age factor to calculate the application＇s effectiveness in different phase.In this way,we could urge the lying servers to stop lying by making them lose more than the honest servers.At the same time,we guaranteed the optimal throughput of system and introduced price mechanism to make honest servers to be more demand-satisfying.The experiment shows the fairness algorithm has a good improvement for lying behavior.