基于转发路径数目的NDN混合拥塞控制机制研究

Investigation of the Hybrid Congestion Control Mechanism for NDN Based on the Number of Forwarding Paths

在命名数据网络(named data networking,NDN)中,拥塞控制是保障用户服务质量(quality of service,QoS)的关键环节.但独特的多源、多路径特性使得TCP/IP架构的端到端拥塞控制方案难以直接应用于NDN.因此,设计一种有效的NDN拥塞控制机制是较为活跃的研究领域.目前,混合拥塞控制逐渐发展成为一种主流的拥塞控制机制;然而,如何及时有效地既能缓解由单路径流引发的拥塞又能缓解由多路径流引发的网络拥塞是混合拥塞控制机制亟待解决的问题.针对该问题,提出了一种基于转发路径数目的混合拥塞控制方案——NFPCC.路由器依据数据包排队时延计算本地节点的拥塞程度,并使用数据包传递当前节点的拥塞信息;下游邻节点提取数据包中的拥塞信息并依据兴趣包的转发路径数量选择多路径转发策略或兴趣包速率整形策略以及时、有效地缓解上游相邻节点的拥塞;最后,消费者依据数据包所传递的拥塞信息持续地地调整拥塞窗口cwnd的尺寸以协作路由器的控制.仿真结果表明,在BRITE场景中,基于所提方案的消费者总吞吐量比基于PCON方案的消费者总吞吐量高91.9%.在路由器启用网络内缓存功能后,基于所提方案的消费者总吞吐量比基于PCON方案的消费者总吞吐量高38.5%.

Congestion control plays a crucial role in guaranteeing quality of service(QoS)in named data networking(NDN).However,the unique multisource and multipath transmission characteristics make it difficult to directly apply the end-to-end congestion control scheme of the TCP/IP architecture to NDN.Therefore,designing an effective congestion control mechanism for NDN is an active research area.At present,hybrid congestion control has gradually been developed into a popular mechanism.However,an effective reduction in the congestion caused by single-path flows and network congestion caused by multipath flows in a timely manner is important for the hybrid congestion control mechanism.Thus,herein,a hybrid congestion control scheme is proposed based on the number of forwarding paths,named NFPCC.The router calculates the congestion degree of the local router based on the queuing delay of the data packets and uses these data packets to deliver the congestion information of the current router;the downstream neighbor routers extract the congestion information in the data packet and select the multipath forwarding strategy or interest shaping strategy based on the number of forwarding paths of the interest packet to mitigate congestion flexibly and in a timely manner.Finally,the consumer continuously adjusts the size of the congestion window based on the congestion information delivered by packets to collaborate with the routers.The simulation results show that the total throughput of consumers deploying the proposed scheme is 91.9% higher than that of consumers deploying PCON in the BRITE scenario.After enabling the router’s in-network caching feature,the total throughput of consumers deploying the proposed scheme is 38.5% higher than that of consumers deploying PCON.