Research On Packet Forwarding Queue Scheduling Mechanism In Time Deterministic Network

With the advent of the Industry 4.0 and 5G era,new network application scenarios have been promoted.With the development of factory automation,autonomous driving and telemedicine technologies,more and more time-sensitive services have emerged,requiring the network to provide high reliability,low latency,low jitter and deterministic forwarding.However,traditional networks only provide best-effort services and cannot guarantee the time-deterministic requirements of the business.IEEE and IETF have successively established the TSN working group and the Det Net working group to promote the development of time-deterministic network,in which time-slotted forwarding is the key technology of deterministic network.However,as the scale of the network increases,the randomness of the service and the complexity of the network environment easily cause the service to fail to be forwarded in the corresponding time slot.In response to this problem,this thesis explores the multi-queue joint scheduling mechanism.The main work and innovative research results are as follows:Summarizes the development status of time-deterministic network and the development process of time-deterministic forwarding technology;focuses on the method of flow shaping algorithm to achieve queue scheduling,analyzes their performance;introduces typical packet forwarding strategies CQF and CSQF,and summarizes the end-to-end delay of slotted packet forwarding technology and the mechanism of using queues to realize slotted forwarding.In response to the problem that packets in the time slot cannot be forwarded in time,a creditbased multi-queue joint scheduling mechanism is proposed to jointly schedule the delayed data queue and the current data queue to ensure the current time slot service delay while coordinating the scheduling of the delayed data queue The output flow rate improves the reliability and resource utilization of the network.Develop a delayed forwarding strategy for the data failed to forward,reserve delayed data in the queue according to the remaining resources of the time slot;for the problem of conflict between delayed data and current data,propose a multi-queue joint scheduling mechanism to support coordinated scheduling of delayed data queue and normal data queue;the sending rate of each queue is designed to jointly optimize the collision probability of delayed data and current data,the probability of delayed data sending,and adjust the sending rate coefficient to ensure service reliability.Finally,the performance of the queue transmission rate selection scheme and the effectiveness of the multi-queue joint scheduling mechanism are verified through experimental simulation.Based on the VPP platform,a time-deterministic network packet forwarding queue scheduling protocol is designed.Based on the analysis and summary of the characteristics of the VPP platform and the protocol stack process,the overall framework of the packet forwarding queue scheduling protocol is proposed.The following modules are mainly designed: service type distribution module,which realizes the function of distinguishing time-deterministic business and BE business;time-deterministic business module,which realizes the enqueue algorithm,dequeue algorithm and queue management function of controlling time-deterministic business;The BE service queue module,which manages the BE service when the time-deterministic service is sent;selects the transmission module with strict priority,and realizes the function of forwarding the time-deterministic service and the BE service according to the priority.The performance of the protocol is then simulated,and the end-to-end delay of the service under different scenarios is statistically analyzed,which verifies the basic functions of the protocol and the ability of the credit-based multi-queue joint scheduling mechanism to improve network reliability.