Моделирование метода ранней диагностики потерь трафика реального времени в программно-конфигурируемых сетях на основе аппарата сетей Петри
Authors: Никишин К.И. 
Published: February 2025

В статье рассмотрена и исследована модель метода ранней диагностики потерь трафика реального времени в программно-конфигурируемых сетях (ПКС) при передаче разнородного трафика в коммутаторе OpenFlow на основе цветных временных иерархических сетей Петри и с использованием пакета моделирования CPN Tools. Разработаны и описаны подсети Петри, моделирующие основной процесс передачи трафика в ПКС. Проведено экспериментальное моделирование с различной загрузкой коммутатора и сравнение результатов разработанного метода с классическим методом передачи разнородного трафика в ПКС.
Introduction. The classic computer network is Ethernet with support for Quality of Service (QoS). The further development of computer networks was the emergence of distributed networks, such as Time-Triggered Ethernet, software defined networks (SDN), cloud computing. The reason for the transition to the development of distributed networks was the limitation of the classical Ethernet computer network for further developments and variations in traffic transmission according to the IEEE 802.1 standard. In SDN the main protocol is OpenFlow, the protocol allows you to process and manage heterogeneous traffic. The main disadvantages of the OpenFlow protocol include a significant increase in the frame search time in the flow tables and a message to the controller about its removal at a late stage of diagnostics until a search occurs in all flow tables, in case of its inconsistency in fields. The aim of the research is improving the efficiency of loss diagnostics of real-time traffic in SDN. Tasks: the construction of a classification of the type of traffic at the switch input, the construction of a Petri subnet of the process of transmitting real-time traffic to the timeout controls in the SDN, the construction of a Petri subnet of the control of hard and idle timeouts, modification of the subnets of the flow table, comparison of the flow with the flow table, experimental modeling with different switch loading and comparison of the results of the developed method with the classical transfer of heterogeneous traffic to the SDN. Methods. A model of the method of early diagnosis of real-time traffic losses in the SDN based on color time hierarchical Petri nets using a free distributed package CPN Tools has been developed and described. The hard timeout and idle timeout control subnets developed recognize the loss of real-time traffic frames at an early stage, and this circumstance allows you to inform the SDN controller about the retransmission of the frame. In connection with the introduction of timeout control by separate subnets, traffic transmission through flow tables is greatly simplified, since there is no control of storage, processing of timeouts using the OpenFlow protocol. Results.An experimental study and comparison of the developed models based on the apparatus of Petri nets was carried out. Measurements of the time from entering the flow table 0 to N and how much time in clock pulses was required to determine the desired rule from the flow table were taken into account. According to the data obtained, the method of early diagnosis of real-time traffic losses in the SDN has proven its effectiveness and provides a reduction in the delay for transmitting real-time traffic with normal switch load 0.8 by 36% on average, the delay of real-time traffic is reduced due to early diagnosis of timeouts in the SDN.