内容中心网络中基于区域集中化控制的协作缓存路由机制*

针对在内容中心网络(Content Centric Networking, CCN)中如何合理放置与高效利用应答数据的问题,该文将集中化控制的思想引入到内容缓存与查找中,提出一种协作缓存路由机制。缓存决策时,通过兴趣包和数据包携带标签的方式,确定沿途最大缓存收益区域;在最大缓存收益区域内,结合内容全局活跃度和节点可用缓存空间,选择内容最佳放置位置。路由查找时,将区域内容放置与路由转发相结合,增大缓存资源可用性。仿真结果表明,与经典算法相比,该机制以少量额外的开销提高了缓存命中率和跳数减少率,改善了缓存负载分布均衡性,提升了CCN网络缓存和传输效率。     

RBC-CC: RBC-Based Cascade Caching Scheme for Content-Centric Networking

With the increasing demand of content dissemination, Content-Centric Networking (CCN) has been proposed as a promising architecture for future Internet. In response to the challenges in CCN caching, we develop an online caching scheme (named RBC-CC) exploiting the concept of Routing Betweenness Centrality (RBC) and “prefetching”, aiming at significantly reducing costly inter-ISP traffic and largely reducing content access hops. Simulation results demonstrate that the proposed caching scheme can significantly outperform the popular caching approaches in terms of the saving rate of inter-ISP traffic. Besides, RBC-CC performs well in reducing the average access hops and incurs the least cache evictions. Further, we present a thorough analysis regarding the impact of access pattern, cache size, content popularity and population on the caching performance. We then come to the conclusion that our scheme is featured with good stability and scalability as well as its effectiveness.     

内容中心网络中基于多样化存储的缓存污染防御机制

针对内容中心网络(CCN)中的缓存污染攻击问题,提出一种基于多样化存储的缓存污染防御机制。对不同业务内容采取差异化缓存从而减小网络受攻击面,将业务划分为三类并采用不同缓存策略:对隐私及实时性业务不予缓存;对流媒体业务以概率推送至网络边缘缓存;对其他文件类内容业务由上游到边缘逐步推送缓存。在不同节点分别配置不同的缓存污染攻击防御手段:对于边缘节点通过内容请求到达概率的变化对攻击进行检测;对于上游节点通过设置过滤规则将请求概率较低的内容排除出缓存空间。仿真结果表明,相比CNN传统缓存策略下的防御效果,该机制使网络平均缓存命中率提高了17.3%,该机制能够有效提升网络对于缓存污染攻击的防御能力。     

ICN中的一种协作缓存机制

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.     

A Centrality-measures based Caching Scheme for Content-centric Networking (CCN)

Content-centric networking (CCN) is gradually becoming an alternative approach to the conventional Internet architecture through the distribution of enlightening information (named as content) on the Internet. It is evaluated that the better performance can be achieved by caching is done on a subset of content routers instead of all the routers in the content delivery path. The subset of a content router must be selected in a manner such that maximum cache performance can be achieved. Motivated by this, we propose a Centrality-measures based algorithm (CMBA) for selection of an appropriate content router for caching of the contents. The Centrality-measures are based on the question: ”Who are the most important or central content router in the network for the caching of contents?”. We found that our novel CMBA could improve content cache performance along the content delivery path by using only a subset of available content routers. Our results recommend that our proposed work consistently achieves better caching gain across the multiple network topologies.     

内容中心网络中基于节点相似度的协作缓存算法

针对内容中心网络中ALWAYS缓存策略节点存储空间利用率低、内容访问时延大、整体网络缓存性能低下的问题,提出了一种依据节点相似度的协作缓存算法。该算法优先将兴趣包转发至最相似节点,增大相关请求的就近响应概率;同时保证在缓存决策中的同一副本在协作节点间不重复存储,在降低冗余的同时增加了缓存多样性。实验结果表明,与现有算法相比,该算法在减少路由跳数和请求时延的同时提高了缓存命中率。     

内容中心网络中DoS攻击问题综述

“内容中心网络”（Content Centric Networking,CCN）是未来互联网架构体系群中极具前景的架构之一。尽管CCN网络的全新设计使其能够抵御目前网络存在的大多数形式DoS攻击,但仍引发了新型的DoS攻击,其中危害较大的两类攻击是兴趣包泛洪攻击和缓存污染攻击。这两类DoS攻击利用了CCN网络自身转发机制的安全逻辑漏洞,通过泛洪大量的恶意攻击包,耗尽网络资源,并导致网络瘫痪。与传统IP网络中DoS攻击相比,CCN网络中的内容路由、内嵌缓存和接收者驱动传输等新特征,对其DoS攻击的检测和防御方法都提出了新的挑战。本文首先介绍CCN网络的安全设计和如何对抗已有的DoS攻击,然后从多角度描述、比较CCN中新型DoS攻击的特点,重点阐述了兴趣包泛洪攻击和缓存污染攻击的分类、检测和防御方法,以及它们所面临的问题挑战,最后对全文进行总结。     

Performance analysis of in-network caching for content-centric networking

With the explosion of multimedia content, Internet bandwidth is wasted by repeated downloads of popular content. Recently, Content-Centric Networking (CCN), or the so-called Information-Centric Networking (ICN), has been proposed for efficient content delivery. In this paper, we investigate the performance of in-network caching for Named Data Networking (NDN), which is a promising CCN proposal. First, we examine the inefficiency of LRU (Least Recently Used) which is a basic cache replacement policy in NDN. Then we formulate the optimal content assignment for two in-network caching policies. One is Single-Path Caching, which allows a request to be served from routers only along the path between a requester and a content source. The other is Network-Wide Caching, which enables a request to be served from any router holding the requested content in a network. For both policies, we use a Mixed Integer Program to optimize the content assignment models by considering the link cost, cache size, and content popularity. We also consider the impact of link capacity and routing issues on the optimal content assignment. Our evaluation and analysis present the performance bounds of in-network caching on NDN in terms of the practical constraints, such as the link cost, link capacity, and cache size.     

基于多层加密机制的内容中心网络隐私保护策略

内容中心网络（Content-Centric Networking,CCN）作为一种新型的网络架构,将通信从基于IP地址的端到端的模式转变为基于内容的模式,成为未来网络最有发展潜力的网络架构之一。CCN网络请求者获得所需内容不用考虑内容存在何处,该网络的优势在于可以在路由器中缓存已请求过的内容。然而,内容、请求者以及发布者三者的隐私保护对于CCN网络是一个新的挑战。提出一种基于多层加密机制的内容中心网络隐私保护策略,在发挥CCN网络缓存优势的情况下,能够防止非法兴趣包请求,同时减轻了路由器以及请求者需要存储大量密钥的负担,提高网络的安全性。     

CCN中基于业务分类和节点分区的混合缓存机制

针对内容中心网络(content centric networking,CCN)中不同业务内容的合理放置问题,提出了一种基于业务分类和节点分区的混合缓存机制。根据不同的业务特征,设计了差异化的缓存策略。对于流媒体点播业务,采用基于流行度的推拉式缓存,实现其在边缘网络的按序存储;对于非流媒体共享内容,采用基于hash的显式缓存,实现其在核心网络的单一副本放置。仿真结果表明,与经典算法相比,该机制提高了缓存命中率和跳数减少率,降低了平均请求时延。     

Hierarchical caches in content-centric networks: modeling and analysis

Content-centric network (CCN) is a new Internet architecture in which content is treated as the primitive of communication. In CCN, routers are equipped with content stores at the content level, which act as caches for frequently requested content. Based on this design, the Internet is available to provide content distribution services without any application-layer support. In addition, as caches are integrated into routers, the overall performance of CCN will be deeply affected by the caching efficiency. In this paper, our aim is to gain some insights on how caches should be designed to maintain a high performance in a cost-efficient way. We try to model the two-layer cache hierarchy composed of CCN routers using a two-dimensional discrete-time Markov chain, and develop an efficient algorithm to calculate the hit ratios of these caches. Simulations validate the accuracy of our modeling method, and convey some meaningful information which can help us better understand the caching mechanism of CCN.     

内容中心网络安全技术研究综述

内容中心网络（Content Centric Networking,CCN）属于信息中心网络的一种,是未来互联网体系架构中极具前景的架构之一,已成为下一代互联网体系的研究热点。内容中心网络中的内容路由、内嵌缓存、接收端驱动传输等新特征,一方面提高了网络中的内容分发效率,另一方面也带来了新的安全挑战。本文在分析CCN工作原理的基础上,介绍了CCN的安全威胁、安全需求以及现有的解决方案,并展望了CCN安全技术研究的方向。首先,详细介绍了CCN的原理和工作流程,对比分析了CCN与TCP/IP网络的区别,并分析了CCN面临的安全威胁及需求。其次,对CCN中隐私保护、泛洪攻击、缓存污染、拥塞控制等技术的研究现状进行归纳、分析、总结,并分析了现有方案的优缺点及不足,进而分析可能的解决方案。最后,对CCN安全技术面临的挑战进行了分析与讨论,并展望了未来的研究方向及发展趋势。通过对已有研究工作进行总结与分析,本文提出了CCN安全技术潜在研究方向与关键问题,为CCN安全后续研究提供有益参考。     

PPP: Prefix-Based Popularity Prediction for Efficient Content Caching in Contentcentric Networks

In the Content-Centric Networking (CCN) architecture, popular content can be cached in some intermediate network devices while being delivered, and the following requests for the cached content can be efficiently handled by the caches. Thus, how to design in-network caching is important for reducing both the traffic load and the delivery delay. In this paper, we propose a caching framework of Prefix-based Popularity Prediction (PPP) for efficient caching in CCN. PPP assigns a lifetime (in a cache) to the prefix of a name (of each cached object) based on its access history (or popularity), which is represented as a Prefix-Tree (PT). We demonstrate PPP’s predictability of content popularity in CCN by both traces and simulations. The evaluation results show that PPP can achieve higher cache hits and less traffic load than traditional caching algorithms (i.e., LRU and LFU). Also, its performance gain increases with users of high mobility.     

基于选择存储的CCN网络缓存发现方法

内容中心网络(Content-Centric Network, CCN)是未来互联网的重要发展方向。网内缓存是 CCN 网络的重要特征,对 CCN 内容传输性能具有重要影响。网内缓存的内容发现效率与网内缓存性能密切相关。传统 CCN 网络缓存发现方法是通过请求包在数据平面转发,沿途机会性地命中缓存实现的,具有一定的随机性、盲目性,可能导致缓存内容无法被高效利用。本文提出一种在控制平面解决缓存可用性的方法,结合拓扑、缓存容量以及用户请求分布计算出“值得”缓存的内容进行存储,同时将其向外通告,使其参与路由计算,以便后续请求快速准确地发现并利用缓存内容。实验结果表明,本文方法可使缓存命中率提高 20%左右,服务器负载降低 15%左右。     

Caching methodologies in Content centric networking (CCN): A survey

Nowadays, Information centric networking has tremendous importance in accessing internet based applications. The increasing rate of Internet traffic has encouraged to adapt content centric architectures to better serve content provider needs and user demand of internet based applications which is based on receiver driven data retrieval. These architectures have built-in network Caches and these properties improves efficiency of content delivery with high speed and efficiency and they are very efficient in comparison with traditional caching of internet access methodologies. By using Information centric architectures, users need not download content from content server despite they can easily access data from nearby caches. User requested content is independent of the location of that data by use of caching approaches and does not rely on storage and transmission methodologies of that content. There has been many researches going to base on caching approaches in the Content centric network. Efficient caching is essential to reduce delay and to enhance performance of the network. Efficient caching is essential to reduce delay and to enhance performance of the network. So, in this paper, we presented a survey on caching approaches and related issues like cache content, availability, and cache router localization and so on. The main focus to present a state-of-art research paper for researchers who are interested in the area of Information centric network so that they can get an idea about what work and issues have been developed and arises in this particular caching field.     

基于均衡数据放置策略的分布式网络存储编码缓存方案

为了保证网络存储的负载平衡并避免在节点或磁盘故障的情况下造成不可恢复的损失,提出一种基于均衡数据放置策略的分布式网络存储编码缓存方案,针对大型高速缓存和小型缓存分别给出了不同的解决办法。首先,将Maddah方案扩展到多服务器系统,结合均衡数据放置策略,将每个文件作为一个单元存储在数据服务器中,从而解决大型高速缓存问题;然后,将干扰消除方案扩展到多服务器系统,利用干扰消除方案降低缓存的峰值速率,结合均衡数据放置策略,提出缓存分段的线性组合,从而解决小型缓存问题。最后,通过基于Linux的NS2仿真软件,分别在一个和两个奇偶校验服务器系统中进行仿真实验。仿真结果表明,提出的方案可以有效地降低峰值传输速率,相比其他两种较新的缓存方案,提出的方案获得了更好的性能。此外,采用分布式存储虽然限制了将来自不同服务器的内容组合成单个消息的能力,导致编码缓存方案性能损失,但可以充分利用分布式存储系统中存在的固有冗余,从而提高存储系统的性能。     

An ANFIS-based cache replacement method for mitigating cache pollution attacks in Named Data Networking

Named Data Networking (NDN) is a candidate next-generation Internet architecture designed to overcome the fundamental limitations of the current IP-based Internet, in particular strong security. The ubiquitous in-network caching is a key NDN feature. However, pervasive caching strengthens security problems namely cache pollution attacks including cache poisoning (i.e., introducing malicious content into caches as false-locality) and cache pollution (i.e., ruining the cache locality with new unpopular content as locality-disruption).In this paper, a new cache replacement method based on Adaptive Neuro-Fuzzy Inference System (ANFIS) is presented to mitigate the cache pollution attacks in NDN. The ANFIS structure is built using the input data related to the inherent characteristics of the cached content and the output related to the content type (i.e., healthy, locality-disruption, and false-locality). The proposed method detects both false-locality and locality-disruption attacks as well as a combination of the two on different topologies with high accuracy, and mitigates them efficiently without very much computational cost as compared to the most common policies.     

CCN中一种改进的面向隐私保护的缓存策略

内容中心网络（CCN）是一种新型的网络架构,但其路由器缓存数据包的模式给用户带来了隐私泄露的风险。提出一种面向隐私保护的动态区域协作缓存策略。该策略以兼顾用户隐私保护的同时提高网络性能为目的进行设计,从信息熵的角度出发,以提高用户的请求信息的不确定度为目标,通过将内容存储在相应的隐匿系数高的缓存节点,增加攻击者确定请求用户的难度;以动态区域协作的方式存储内容,增大缓存内容的归属不确定性,以加大攻击者定位数据包的难度。仿真结果表明,该策略可降低内容请求时延,提高缓存命中率。     

Design, implementation, and evaluation of differentiated caching services

With the dramatic explosion of online information, the Internet is undergoing a transition from a data communication infrastructure to a global information utility. PDAs, wireless phones, Web-enabled vehicles, modem PCs, and high-end workstations can be viewed as appliances that "plug-in" to this utility for information. The increasing diversity of such appliances calls for an architecture for performance differentiation of information access. The key performance accelerator on the Internet is the caching and content distribution infrastructure. While many research efforts addressed performance differentiation in the network and on Web servers, providing multiple levels of service in the caching system has received much less attention. It has two main contributions. First, we describe, implement, and evaluate an architecture for differentiated content caching services as a key element of the Internet content distribution architecture. Second, we describe a control-theoretical approach that lays well-understood theoretical foundations for resource management to achieve performance differentiation in proxy caches. An experimental study using the Squid proxy cache shows that differentiated caching services provide significantly better performance to the premium content classes.     

一种基于内容流行度和社团重要度的ICN缓存与替换策略

现有以信息为中心的网络(Information-Centric Network,ICN)缓存的内容的时空分布不够合理,存在无效缓存及同质化缓存等问题。对此,文中提出一种基于内容流行度和社团重要度的ICN缓存与替换策略,其结合内容流行度与节点的社团重要度来选择缓存节点,把具有不同流行度的内容分散缓存在社团重要度不同的节点上,使缓存内容的空间分布趋于合理,从而增加了缓存内容的多样性。同时,基于社团局部流行度来替换缓存内容的策略更有利于优化缓存内容的时间分布,实现缓存内容空间分布的动态调整。实验结果表明,所提策略能有效地减少用户请求的平均响应时间,提高缓存对象的命中率和全网的缓存差异度。