Research On Time Slotted Forwarding Technology In Time Deterministic Network

Time deterministic network refers to the communication network that can provide deterministic end-to-end delay for traffic flows.In recent years,with the emergence of new applications such as industrial Internet,automatic driving,virtual reality and tactile Internet,time determinability has become an essential feature of high-speed IP networks.However,the best-effort packet forwarding mechanism in traditional makes it difficult to ensure the deterministic latency.After nearly 10 years of development,time-sensitive network standards have been able to support deterministic flow transmission in small-scale networks.Nevertheless,how to implement time deterministic packet forwarding in large-scale networks becomes one of the problems that the Deterministic Networking Working Group is currently committed to solve.This thesis focuses on the time deterministic forwarding problem in large-scale networks,and the main work and innovative results are as follows.This thesis analyzes the reasons why the deterministic latency of the traditional Internet is difficult to ensure,summarizes the evolution process of time deterministic network technologies,and discusses the key technologies of time deterministic network based on the time-slotted forwarding mechanism.Meanwhile,the advantages of the time-slotted model in bandwidth resource characterization and reservation are introduced,and the feasibility of the time-slotted model for deterministic delay guarantee in the packet forwarding process is also introduced,followed by the summary of the current challenges faced by the deterministic forwarding technology.This thesis proposes a time-slotted routing information carrying and distribution mechanism based on source routing,which introduces routing information and packet forwarding information in the packet header to specify the forwarding time slot of the packet at each node for avoiding the delay caused by micro bursts.A remaining capacity-based extra-slot packet scheduling mechanism is proposed,which can fully utilize the transmission resources to avoid the packet loss problem when the time slot is not aligned.Meanwhile,the analysis of the end-to-end delay and the overflow probability in slotted queues is given.A time-slotted routing algorithm based on the equalization of adjacent time slots is proposed to solve the problem that time determinability cannot be ensured due to non-alignment of time slots.Through Matlab simulation,the efficiency of the proposed algorithm is verified.A deterministic time-slotted packet forwarding protocol is designed,which is compatible with the best-effort Internet Protocol(IP).By utilizing a multi-queue mechanism,this protocol can achieve time-slotted packet scheduling,where each queue corresponds to a specific time slot.Compared with the traditional packet forwarding protocol,the main updates are as follows.One is to add the forwarding time information in the source routing header.Based on the segment routing mechanism,the process of extracting the forwarding time slot information is added.Combined with the routing module and the packet scheduling module,the forwarding time slot of time-sensitive traffic packets at each node on the transmission path is determined to ensure end-to-end latency and jitter performance.The second is to design differentiated transmission queues and management rules.In response to the forwarding requirements of traffics with different delay-sensitive levels,the cyclic timeslotted queue,best-effort queue,and long-term caching queue are built,which can support the time-slotted forwarding of delay-sensitive traffic packets for ensuring the deterministic latency,and the storage-carry-forward of non-sensitive traffic packets for improving the utilization ratio of network resources.