Switched Real-Time Ethernet in Industrial Applications - Asymmetric Deadline Partitioning Scheme

This paper presents work on a switched Ethernet network extended to allow for periodic real-time traffic, using earliest deadline first (EDF) scheduling. A scheme of asymmetrically dividing deadlines of real-time channels between the in and outgoing links to/from the switch is proposed (ADPS). The result of the simulations of setting up RT channels over a full-duplex switched Ethernet network is presented. The simulations show that the ADPS performs well when master-slave communication is assumed over the network. thin layer is needed between the Ethernet protocols and the TCP/IP suite in the end-stations. The switch is responsible for admission control, while both end-stations and the switch have EDF (Earliest Deadline First) scheduling (7). The deadlines of messages over the network are end-to-end based, insofar as it is the maximum time to deliver, from the release time in the source node, to the arrival in the destination. In this paper, we assume a single switch, with one node connected to each physical port. The messages originating from the source do therefore traverse two links, and we need to provide guarantees for the time to deliver over both links. We approach this problem by dividing the end-to- end deadline into two, one for the source to the switch, and one from the switch to the destination. The deadline can be partitioned in a number of ways. The method we choose affects the system. The paper is concerned with analyzing the partitioning of deadlines, and to propose a way that is more suitable for master slave communication, which is a common demand in industrial applications. The results, and indeed the method in its current form, do not refer to a mixed topology. The network topology is confined to a star, with one centralized switch connected to one node on each physical port. A full-duplex network is assumed. The rest of the paper is organized as follows. The network architecture is presented in Section 2. In Section 3, a feasibility analysis is introduced. In section 3, the Asymmetric Deadline Partitioning Scheme (ADPS) with the simulation results are presented