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Network Redundancy for Industrial Automation

Posted on Dec 19, 2023 by
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industrial switch

Industrial communications networks are the backbone of modern industrial operations, enabling seamless data transfer and control in manufacturing environments. However, these networks face myriad challenges such as data loss, network latency, equipment failure, etc., which can lead to delays, downtimes, and potentially significant financial losses. To fortify against such catastrophes, network redundancy emerges as the shield, ensuring continuity and resilience in these critical networks. In this article, we will delve deeper into the significance of network redundancy and how it addresses these challenges and ensure seamless operation in industrial automation.

Understanding Industrial Network Redundancy

Network redundancy, in its essence, operates on the principle of duplicating critical network components to ensure uninterrupted connectivity. By creating redundancy, industrial communication networks can continue functioning even when failures or disruptions occur, guaranteeing uninterrupted connectivity and services. This redundancy can be implemented at various levels, including hardware, software, and systems. Its significance in industrial automation cannot be overstated—it's the fortification that keeps communication networks resilient and operational.

The Significance of Industrial Network Redundancy

Industrial network redundancy offers several advantages crucial for maintaining robust and uninterrupted industrial communication networks:

  • Enhanced Reliability: The reliability of industrial communication networks means the accuracy and timeliness of data. Redundant solutions can improve network reliability by eliminating single points of failure, reducing data transmission errors and ensuring instant delivery of data. When a network component (such as a router, industrial switch, power supply, etc.) fails, it can automatically switch to an alternate path or device to ensure the continuity and reliability of data transmission.

  • Fault tolerance: Network redundancy acts as a safety net, ensuring that if one component fails, there are backups in place to immediately take over the operations. This fault tolerance prevents minor disruptions from cascading into major operational downtime.

  • Minimal Downtime: With network redundancy in place, the downtime experienced during network failures is significantly reduced or eliminated altogether. The system’s ability to swiftly switch between primary and redundant components ensures uninterrupted operations.

  • Improved Resilience: Redundant setups improve the network's resilience against various types of failures, be it power outages, equipment malfunctions, or cable damage. This resilience contributes to the overall stability of the network.

Common Network Redundancy Solutions for Industrial Automation

Network redundancy solutions encompass a spectrum of technologies designed to bolster industrial communication networks. In industrial automation, redundancy is implemented across various facets:

Power Redundancy

In industrial automation, machinery, control systems, and data processing heavily rely on stable power sources. Any interruption in the power supply can result in a significant decrease in productivity, potential equipment damage, and even compromise safety measures.

Power redundancy refers to implementing backup power sources and systems to ensure continuous and uninterrupted supply of power to critical components within industrial setups. This redundancy is essential to prevent disruptions, equipment failures, or downtime caused by power outages or fluctuations. It involves various strategies, including Uninterruptible Power Supplies (UPS), redundant power supplies, dual power supplies, and more.

industrial switch

Hardware Redundancy

This type involves duplicating physical components, such as switches, cables, or routers, with backup devices deployed at key locations to ensure continued availability of network equipment. When the main device fails, the backup device can automatically take over the work to ensure the normal operation of the network.

Path Redundancy

Redundant paths improve network availability and reliability by using multiple independent paths to transmit data. When a path fails, the system automatically reroutes data through available alternate paths to ensure continuity of data transmission. The redundant path design can adopt vertical, horizontal, ring or mesh topology structures, which can be flexibly selected according to actual application scenarios.

Moreover, redundant path design can use dynamic routing protocols to manage path redundancy. These protocols continuously analyze the network topology and traffic conditions, dynamically selecting the most efficient path for data transmission. Load balancing technology can also be incorporated to ensure data is distributed across multiple paths, optimizing network performance and preventing congestion on any single path.

industrial switch

Redundancy Protocol

Basic duplicate components, paths, or manual failover mechanisms, these initial setups, while offering a semblance of redundancy, provide only limited fault tolerance and therefore require more complex solutions. In industrial-grade switches, protocol redundancy stands as a primary feature, making the supported types of redundant protocols significantly important.

The emergence of early protocols like Spanning Tree Protocols (STP) marked a pivotal stride. While effective in preventing network loops, these protocols faced challenges with longer recovery times following topology changes. As a result, the Rapid Spanning Tree Protocol (RSTP) and Multiple Spanning Tree Protocol (MSTP) replaced STP and were optimized to significantly reduce recovery time, enabling swift adaptation to network alterations and bolstering redundancy capabilities.

Dedicated protocols, such as High Availability Seamless Redundancy (HSR), Parallel Redundancy Protocol (PRP), Media Redundancy Protocol (MRP), and Device Level Ring (DLR), emerged as game-changers. Tailored specifically for industrial needs, these protocols introduced zero-time recovery, redundant frame transmission over independent LANs, and rapid fault detection and rerouting, ensuring uninterrupted communication and eliminating single points of failure.

The following is a comparative introduction to these redundancy protocols:

Protocol
Definition
Topology
Fault Recovery Time
Application
Spanning Tree Protocols (STP)
 
Prevents network loops by blocking redundant paths. Slower convergence after topology changes.
Tree
10-50 seconds
General Ethernet networks, less time-sensitive
Rapid Spanning Tree Protocol (RSTP) / Multiple Spanning Tree Protocol (MSTP)
Faster convergence than STP, reduced recovery times, supports multiple spanning trees.
Tree
3~5 seconds
Ethernet networks, faster convergence
High Availability Seamless Redundancy (HSR)
Zero-time recovery for industrial automation networks. Redundant paths for continuous data transmission.
Ring
0 ms
Industrial automation networks
Parallel Redundancy Protocol (PRP)
Sends duplicate frames over independent LANs. Zero-time recovery without relying on recovery times.
Mesh
0 ms
Critical industrial systems
Media Redundancy Protocol (MRP)
Operates at the media level, detects faults, and automatically reroutes traffic for rapid recovery.
Ring
10 ms, 30 ms, 200 ms or 500 ms
Industrial automation, lower network layers
Device Level Ring (DLR)
Implements ring topologies at the device level for swift data rerouting in case of link failures.
Ring
<3 ms
Industrial automation, EtherNet/IP networks, device-level redundancy

System Redundancy

The failure of certain components in factory automation, process industry or substation automation applications, which never can be totally avoided, have to be handled in a way that minimizes the influence on the system. High availability can be achieved by using complete system redundancy – every device is doubled using duplicated servers, controllers, industrial switch, sensors and actuators, as well as duplicated networks. Implementing backup systems or entire redundant networks can ensure seamless operation even if the primary system faces a catastrophic failure. However, complete system redundancy is the most expensive way of high availability.

industrial switch

How to Choose These Network Redundancy Solutions

Choosing network redundancy solutions for industrial networks involves a meticulous process, considering various critical aspects to fortify the network's resilience and ensure uninterrupted operations.

Begin by gaining a deep understanding of the specific needs of the industrial network. Assess data criticality, latency tolerance, scalability, and fault tolerance requirements. For example, some networks demand zero downtime, while others might allow for minimal disruptions.

Explore a range of network redundancy options, such as hardware, paths, protocols, systems, and evaluate their compatibility with the network infrastructure, including factors like ease of implementation, interoperability, and compliance with industry standards. Also, you need to consider whether the network is a ring, star, or mesh structure and choose protocols aligning with these layouts.

Finally, it’s also critical to consider budget and space constraints, including hardware, software, training and ongoing support expenses.

Conclusion

Network redundancy in industrial communication networks is not merely a precautionary measure; it's a strategic imperative. By embracing redundant Ethernet and its associated technologies, industrial setups fortify their communication networks, ensuring resilience against disruptions that could otherwise hamper productivity and profitability. In the ever-evolving landscape of industrial automation, the strategic deployment of network redundancy solutions emerges as a cornerstone in sustaining seamless operations, mitigating risks, and fortifying the backbone of industrial communication networks.

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