Research On Differentiated Services In NDN

With the expansion of network scale and the rapid growth of content in the network,end-to-end IP network architecture is gradually difficult to meet the needs of more and more large-scale content distribution.Researchers have proposed a new content-centric network architecture--Named Data Networking(NDN).Similar to IP networks,different users or different types of applications in the NDN have different requirements for delay,jitter,or packet loss,and therefore have different quality of service requirements.However,the existing caching strategy research and routing nodes rarely consider the characteristics of different content and their service quality requirements when processing the arriving data packets,so it is difficult to apply to the actual scenarios where the service types are diverse and the user requirements are complex.This dissertation draws on the DiffServ model widely used in IP networks to provide differentiated services.By analyzing the content characteristics and quality of service requirements in the network,and optimizing the caching and forwarding behavior when router nodes process data packets,this dissertation proposes a differentiated service cache and scheduler scheme for NDN.The caching algorithm and the distinguishing scheduling algorithm enable different types of content to obtain different sizes of cache resources and bandwidth resources,so that the limited network resources can be more fully utilized to meet different service quality requirements.In order to realize the differentiated service in NDN,this dissertation mainly does the following research work:(1)According to the content characteristics and their sensitivity to latency,a cache content classification model is proposed to classify the content arriving at router nodes.Based on the classification model,a probability cache placement policy DiffCache is proposed that considers both the content category,the router local popularity,and the content download delay.By dynamically assigning cache resources to different types of content with different caching probabilities,more cache resources can be obtained for delay-sensitive,reusable content.(2)Based on the service classification in the DiffServ model,a forwarding content classification model suitable for NDN is proposed to classify the content arriving at router nodes.Based on the classification model,the behavior of the routing node to process the data packet is optimized,that is,the queue scheduling algorithm is used to allocate different bandwidth resources among different content types when forwarding the data packet,and observe the throughput of different types of content in the network transmission process,the delay,and the impact of packet loss.The experimental results on ndnSIM show that the differential caching algorithm can dynamically allocate cache space to different types of content,and significantly distinguish the performance index of each content type without affecting the global hit rate and download delay.The WRR queue scheduling algorithm in the distinguishing scheduling algorithm can realize the bandwidth allocation between different types of content.When the bandwidth resources are tight,each type of content has a relatively stable throughput.The combination of the cache algorithm and the differentiated scheduling algorithm can allocate more cache resources to content with high latency and reusability,and allocate more bandwidth resources to content with high latency and real-time requirements,thus flexibly meeting the delay requirements of multiple service types.