A Comparison of Techniques for Reducing Unicast Traffic in HSR Networks

Abstract

This paper investigates several existing techniques for reducing high-availability seamless redundancy (HSR) unicast traffic in HSR networks for substation automation systems (SAS). HSR is a redundancy protocol for Ethernet networks that provides duplicate frames for separate physical paths with zero recovery time. This feature of HSR makes it very suited for real-time and mission-critical applications such as SAS systems. HSR is one of the redundancy protocols selected for SAS systems. However, the standard HSR protocol generates too much unnecessary redundant unicast traffic in connected-ring networks. This drawback degrades network performance and may cause congestion and delay. Several techniques have been proposed to reduce the redundant unicast traffic, resulting in the improvement of network performance in HSR networks. These HSR traffic reduction techniques are broadly classified into two categories based on their traffic reduction manner, including traffic filtering-based techniques and predefined path-based techniques. In this paper, we provide an overview and comparison of these HSR traffic reduction techniques found in the literature. The concepts, operational principles, network performance, advantages, and disadvantages of these techniques are investigated, summarized. We also provide a comparison of the traffic performance of these HSR traffic reduction techniques.

Seamless CAN: A Novel Fault-Tolerant Algorithm and Its Modeling

“…However, HSR is known for generating excessively redundant traffic in a network in order to achieve seamless redundancy. Therefore, our future study will focus on applying many traffic reduction techniques [34] to improve seamless CAN's traffic performance. In addition, we believe that implementing seamless CAN with our recently developed HSR switching node SwitchBox will enable seamless CAN to be applied to any network topology with reduced unnecessary traffic.…”

Enhanced Effective Filtering Approach (eEFA) for Improving HSR Network Performance in Smart Grids

“…Several approaches have been proposed to solve this problem that is faced in the standard HSR protocol. Two main types of traffic reduction approaches are available: the traffic filtering-based approach and the dual paths-based approach [6]. In the former, redundant unicast traffic in HSR networks is reduced by filtering the traffic for rings and/or by preventing the traffic from being duplicated and circulated in rings.…”