为了克服现有 Internet 架构存在的众所周知的缺点,未来网络的研究成为热点.ICN(information-centric networking)在众多新架构中正逐渐被公认为最有前途的方案.它把传输的内容缓存到沿途的节点.高效的缓存机制是它的一个重要研究方面.为此,提出了一种在分布式缓存机制中嵌入中心式缓存决策的机制(content-aware placement,discovery and replacement,简称APDR),它把内容的放置、发现、替换统一起来考虑,实现内容的有序缓存,提高网络的性能.APDR的主要思想是：Interest报文除了携带对内容的请求以外,还收集沿途各节点对该内容的潜在需求、空闲缓存等信息,使得Interest的汇聚点和目的地节点可以据此计算出一个缓存方案,并把该方案附加在Data报文上,通知返程途中的某些节点缓存该内容并设置指定的缓存时间.在多种实验条件下对APDR进行了仿真验证,结果表明,APDR 可以改善网络性能,包括缓存命中率、接入代价、替换数量、转发效率以及缓存鲁棒性等；而且APDR的额外开销也不大.%With the emergence of information-centric networking (ICN) in which in-networking caching distinguishes it from other Internet architecture, efficient caching becomes increasingly attractive, but remains of great challenge as current Web caching. This paper proposes a distributed scheme that is embedded with a locally central model, called APDR (i.e., content-aware placement, discovery and replacement). In APDR, according to the information carried on Interest message, the destination of the Interest makes caching decision for the nodes along the path, including different time that the requested content will be cached in different nodes. Finally, the study evaluates the proposed scheme through extensive simulation experiments in terms of a wide range of performance metrics. The experiment results show that the scheme can yield a significant performance improvement over diverse operating environments, such as,cache hit ratio, average access cost, number of replacement, forwarding efficiency and cache robustness etc. At the same time, additional overhead of APDR is small.
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