Research On Traffic Scheduling In Time-Sensitive Communication Networks

The Industrial Internet is a new industrial ecology,critical infrastructure and application model that is deeply integrated industrial manufacturing with the new generation of information and communication network technology.Industrial network is the foundation of the industrial Internet,which has developed from the original Industrial Bus to the Industrial Bus and Industrial Ethernet coexist.However,the fragmented industrial network technologies are specially designed for specific levels of industrial systems and cannot fully satisfy the requirements of the connections of human and human objects.Time-Sensitive Networking(TSN),a standardized next-generation Ethernet technology,has the ability to ensure the deterministic transmission of data and support interoperability of industrial networks.It becomes an important technology foundation for the normalized evolution of industrial networks.With the emergence of time-sensitive communication applications in many industry sectors,TSN,as a new network modality,faces the challenges from service diversity,large-scale traffic flows,and multi-domain network transmission.How to ensure the end-to-end deterministic traffic scheduling becomes a crucial problem for those challenges.To solve the problem,this dissertation uses network virtualization ideas and Software-Defined Networking(SDN)paradigm to study the time-sensitive communication network architecture,and proposes corresponding policies and methods from scalable traffic scheduling,large-scale traffic scheduling and multi-domain traffic scheduling.The main work and innovation are as follows.(1)A Software-Defined Time-Sensitive Networking(SD-TSN)architecture and a traffic scheduling policy integrated service orchestration are proposed.The SD-TSN architecture separates network control from the traffic shaping mechanisms of underlying network according to the SDN paradigm,and integrates service orchestration with network control.The traffic scheduling policy uses the Virtual Network Function(VNF)to build the service chain,and uses the mapping algorithm to map VNFs to the TSN network,which can adjust the time slot width for traffic transmission according to different service requirements to achieve scalable traffic scheduling.The SD-TSN architecture and traffic scheduling policy are evaluated by use case simulation and measurement experiments,and the results show that the SD-TSN architecture and the proposed scheduling policy can effectively support the deterministic transmission of various service traffic,and significantly reduce the delay and jitter of traffic flows while ensuring the bounded delay of time-critical traffic flows.(2)For large-scale traffic scheduling,a Virtual Queue based TimeAware Scheduling(VQ-TAS)method is proposed.This method takes the physical queue as the scheduling unit of the TSN data plane,and introduces the virtual queues in the control plane based on the network virtualization idea.The virtual queues are assigned for each traffic flow,and the virtual queue mapping realizes the mode conversion of the perflow scheduling in virtual queues to per-class scheduling in physical queues.It guarantees the scheduling performance on the level of traffic flows without changing the physical network.The VQ-TAS algorithm is also proposed,including two stages of virtual queue mapping and Gate Control List(GCL)generation.The aggregation mapping process is designed in the virtual queue mapping stage to reduce the runtime of the algorithm.The simulation results in typical industrial use cases show that the proposed method can solve the limitation of fixed resource granularity of physical queues and effectively realize the scheduling of a large number of time-critical traffic flows.(3)A multi-domain extension framework of SD-TSN is designed and a multi-domain time-aware traffic scheduling method is proposed.The multi-domain extension framework adopts collaborative control mode and introduces domain controller and coordinated controller in the control plane,which is responsible for intra-domain control and interdomain coordination,respectively.The traffic scheduling scheme for connection of multiple TSN network domains is designed.According to the scheme,the delay window constrained traffic scheduling method is proposed.The method converts the deadline requirements of time-critical traffic flows into delay windows and divides the delay window by taking the network domain as the unit in the inter-domain scheduling stage.In the intra-domain scheduling stage,the GCLs of the TSN domains are generated under the constraint of delay window.Through industrial use case simulation and measurement experiments,the multi-domain transmission performance of time-critical traffic flows is evaluated.The results show that the proposed method can effectively ensure the bounded delay of time-critical traffic flows in multi-domain transmission,and achieve delay variations in microseconds.