Research On Virtual Domain Based Routing Mechanism For Content Centric Networking

Accompanied with the increasing content distribution applications on the Internet,the consumption of content in current network is exploding,and the proportion of mobile traffic consumption in the network is increasing gradually as well.The traditional network,which is set up based on host to host communication mode,will be overwhelmed in all these growing gigabytes and even terabytes of data transmission.Therefore,Content Centric Networking(CCN),this kind of future Internet architecture,has been born.CCN adopts a name-based routing to fetch the content with its name instead of its location.In addition,it further improves content distribution efficiency with in-network caching,and provides benefits like multi-source content retrieval,multicast,etc.In recent years,the research on CCN mainly includes the following aspects:cache management,routing decision and mobility support.However,routing technologies are involved in the other aspects.With the cornerstone of CCN development,the research of CCN routing technology is crucial and suffers from several problems.Given that the namespace is several orders of magnitude higher than the IP address space,CCN routing suffers more severe scalability issue than traditional Internet does.Meanwhile,the content mobility is remained as one challenge due to the binding between content name and locator that underlies the name-based routing.Furthermore,how to effectively use in-network caching to improve the distribution efficiency is also a challenge.Facing these challenges,researchers have proposed many solutions,but they either sacrifice some features of CCN or focus on part of these problems.Based on this,this dissertation mainly designs virtual domain based routing mechanism for CCN,and major innovations and contributions are summarized as follows.(1)Aiming at the scalability issue brought by the huge storage pressure of CCN FIB,this dissertation proposes a virtual domain-based routing model for CCN.At first,for the sake of facilitating name aggregation,we propose the concept of virtual domain and build hierarchical virtual domain network according to the hierarchical content names to realize domainlevel aggregation.Then,to decrease FIB entries further,we design a new FIB structure which maintains routes to names in hierarchical routing tables built based on the hierarchical virtual domain network.Finally,we present the virtual domain based routing scheme for CCN to direct the forwarding of content requirements.The experimental results demonstrate that the proposed hierarchical virtual domain network can reduce the route states maintained in FIB effectively.And as the number of virtual domain layers increases,the advantage of routing model in scalability increases.In addition,the experimental results also reflect the negative impact of the increase of domain layers on the routing efficiency,which shows that the tradeoff between scalability and routing efficiency,and points out the direction for further research.(2)To further improve and vertify the performance of the virtual domain based routing model for CCN,we propose a two-level virtual domain-based routing scheme for CCN.Considering the tradeoff between scalability and routing efficiency in the routing model,a twolayer virtual domain network is established to minimize the influence of the number of domain layers on routing efficiency while ensuring the hierarchical structure of the virtual domain network.The number of virtual domains is adjusted to assess the impact of the number of virtual domains on the number of route states maintained in FIB.A simple cache management scheme and the corresponding forwarding processing are presented to optimize routing model with improved cache hit.The experimental results demonstrate that the virtual domain network can improve scalability effectively even with the least layering(two layers).And comparing to the state of art,the proposed mechanism has better comprehensive performance on scalability,cache utilization and routing efficiency.In addition,the experimental results show the influence of the number of virtual domains on scalability,which points out the direction to improve the scalability of the routing model further.(3)To improve scalability of virtual domain based routing model further,we present an enhanced scalable virtual domain-based routing scheme for CCN.Aiming at the scalability of FIB population,we propose a two-stage routing protocol to mitigate the huge populating overhead to build FIB in CCN.For the FIB storage pressure,we study the influence of virtual domain structure on the number of routing entries,and present improved methods to shrink FIB by optimizing virtual domain structure.In addition,we discuss and analyze the mobile support of content providers in the virtual domain based routing model.The experimental results demonstrate that the proposed mechanism reduces the FIB entries in a router significantly,and at the same time decreases the populating overhead for creating FIB.(4)For the path stretch arose by inter(virtual)domain routing,leveraging the in-network caching,we propose an efficient virtual domain-based routing scheme for CCN to address scalability and improve routing efficiency with fetching closer replica for consumer.It analysises and calculates the request arrival rate of router in inter-domain routing,and designs a greedy cache management strategy to enhance routing efficiency.The greedy cache management strategy solves cache allocation and replica placement based on content popularity and router's request arrival rate,and decreases path length by increasing cache hit.Performance evaluation shows that the proposed mechanism significantly shortens path length by improving cache hit ratio without compromising the FIB scalability.(5)To overcome the routing challenges arose by the movement of content producer,we propose a mobility support virtual domain-based routing scheme for CCN.For sake of scalability in terms of FIB storage and FIB update,we establish a heterogeneous virtual domain network to manage routes to stable content and routes to mobile content,to cut down FIB entries and remove the influence of mobile content on route state.Meanwhile,we present the corresponding mobile support routing protocol and forwarding mechanism to perform FIB population and interest forwarding.In addition,considering the impact of content producer migration on time-delay sensitive services,a fast handover mechanism is proposed to reduce the handover latency with a lower handover overhead.The experimental results demonstrate that the proposed mechanism can not only improve scalability,but also effectively cut down the handover latency and overhead.In summary,this dissertation introduces the concept of virtual domain and designs the virtual domain-based routing model for CCN to address scalability issue firstly.Then,four routing mechanisms are proposed on the basis of the virtual domain-based routing model to further optimize and verify the feasibility and effectiveness of the routing model,enhance routing scalability,improve routing efficiency and support content mobility.And the feasibility and effectiveness of these routing mechanisms are demonstrated by comparing with some current solutions.