Research On Time Sensitive Network Resource Scheduling And Implementation

With the development of Internet technology,more and more new applications need a deterministic network with low delay,while it is difficult to avoid the delay uncertainty caused by network congestion in the traditional Ethernet when traffic bursts.Time sensitive network(TSN)comes into being.It uses a series of technologies such as priority division,traffic shaping and resource reservation to realize low time delay and low jitter communication.Most of the existing researches consider the deployment of TSN network in industrial environment and implement the related protocol standards of TSN on the hardware switch.In edge computing,cloud computing and other scenarios,TSN is also useful.Due to the application of computing virtualization technology,multiple VMS can run independently and concurrently on a single physical server.Software switches are used to exchange data between VMS and between VMS and external servers.Therefore,supporting TSN protocol standards on software switches is also an essential part of realizing deterministic low latency.This thesis studies how to implement the time-aware shaper and asynchronous traffic shaper and their corresponding traffic scheduling models on the software switch Open VSwitch(OVS).First of all,this thesis analyzes the whole processing process of data packets from receiving to sending in OVS,and adds a traffic shaping framework to support shaper switching,dynamic configuration and other operations.Based on this framework,this thesis carries out the implementation according to the frame processing principle of the time-aware shaper(TAS)in the standard,and introduces the relevant data structure design and the core processing function.Then,this thesis analyzes the traffic scheduling process based on TAS,considers the constraints such as link conflict,delay requirements,forwarding storage and deterministic queue,and establishes an integer linear programming model.Based on the solution results of this model and considering the design of protection tape,the TAS configuration information of each port is finally generated.Finally,the network topology is built on three servers for experiments.The results show that TAS can reduce the maximum delay of packets from 2500 us to 380 us,and the packet loss rate from 50%to zero.TAS requires strict time synchronization,does not support aperiodic traffic,and is sensitive to software jitter,which results in limited application scenarios.Therefore,this thesis also implements an asynchronous traffic shaper(ATS)on OVS,which provides bandwidth resources for time sensitive(TS)services through strict priority and queue rate limiting,so as to achieve deterministic low latency.In order to prevent the congestion of best-effort service due to the short-board effect,this thesis establishes a TS flow scheduling model based on load balancing,and designs a heuristic algorithm to solve it,which supports online flow scheduling.The packet-level simulation experiments on the network topology with 13 switching nodes show that the ATS implemented in this thesis can effectively ensure that the average end-to-end delay of TS stream is consistent with the link propagation delay,and achieve zero packet loss.