High availability and redundancy are crucial for industrial networks, especially for mission-critical applications such as city surveillance, production, automation and power plants where recovery time is a serious concern. If there is a link failure, the impact can quickly become business-critical. Therefore, maintaining max. uptime is the key to backing up your systems in an unstable environment and keeping all equipment running at peak performance. System availability is calculated by dividing uptime by the total sum of uptime and downtime, and the world-glass availability is above 90% or higher.
Of course, there are factory floors where no type of redundancy or recovery solutions have been established, but in such scenarios, the chances of data loss and network downtime can be significantly higher. For this reason, all network administrators in industrial applications need to establish a network that is available 99% of the time to let all network nodes continue to operate when a network disaster occurs. When constructing a 100% reliable architecture for an Ethernet network in industrial applications, we should first point out a robust connection between LAN switches is a must. Though you might decide not to establish complete system redundancy due to space and budget limitations, you can greatly improve your network reliability by employing an industrial managed switch.
What’s an Industrial Managed Switch?
The industrial managed switch offers advanced managed features and traffic controls to meet the evolving demands of today’s industrial networks. With the industrial managed switch, you can achieve more than basic communications. You can configure the performance for each network port and monitor the status of your network more easily. Advanced managed switch features include QoS, VLANs, SNMP, IGMP snooping, port mirroring, bandwidth control, LACP, RSTP, DHCP, ERPS, etc. Moreover, the industrial managed switches usually have a remotely accessible console, command-line or Web GUI, which enables administrators to configure the parameters from different physical locations. Moreover, the industrial network switches are often equipped with an IP30 (or higher) metal enclosure, designed to withstand extreme temperatures (-40°~75°C), shock and vibration, noise, penetrative articles, etc.
How ERPS Improves Network Redundancy?
Ethernet Ring Protection Switching (ERPS) is a standard feature in managed switches, an advanced form of ring topology which enables rapid convergence and carrier-grade reliability in the event of a link failure and ensures large amounts of traffic flow to multiple connection ports. All network nodes are connected in rings. If one of the links is disconnected from the rest of the network, data can still reach its destination through another link. So technically, there’s no network downtime. And this topology can be configured on any data port of the managed switch, including the fiber ports. ERPS works in the same way as RSTP (Rapid Spanning Tree Protocol) and STP (Spanning Tree Protocol), but the main difference will be the recovery time. ERPS allows networks to recover within 20 ms (10G/1G Ethernet recovery time <50 ms), while RSTP takes less than 10 seconds, and STP takes 30-50 seconds.
Moreover, most industrial network switches support redundant power supplies. They will be hooked up to a backup power supply in case of a power outage and the backup power will take over if the main power supply fails, so as to reduce losses and minimize downtime.
Fast Ring Applications
The Fast Ring protocol supports various types of flexible yet simple ring topologies, such as single ring, dual ring and ring coupling, to improve the reliability of the entire network.
1) Single Ring/α-Ring
In such a topology, the Ethernet switches are linked together in a single ring. This mechanism is usually used to cover a large area with a network to save cabling costs while retaining the failover function. It helps to create a high-speed network redundancy mechanism that can recover from a network breakdown in less than 20 milliseconds.
2) Dual Ring
Dual ring is a redundant network topology where network switches are connected using two concentric rings, ideal for small networks that are not frequently reconfigured. Typically, the secondary ring is used as the backup link in case the primary ring fails. In this topology, data travels in opposite directions around the rings. Each ring is independent of the others until the primary ring fails and the two rings are connected to continue traffic.
3) Ring Coupling/Trunk
In network topology, two or more rings are connected with Ring Coupling. This enables a single large ring that contains numerous switches to be broken into smaller, more manageable rings to ensure network efficiency and performance. Using Ring Coupling, one domain can be connected to another domain running any redundancy protocol.
4) Tangent Ring
This mechanism allows two rings from different domains to be connected by a node to form a This type of network is commonly used in the connection between the aggregation ring and the access ring as a backup link of the network. The faulty link can be cut off immediately to ensure the normal forwarding of traffic between ring networks.
5) Intersecting Ring
In the intersecting ring, a sub-ring is often added as a backup link for the primary ring. If the primary ring fails, the packet will be transmitted through the sub-ring to ensure normal traffic forwarding. But these two rings must come from the same domain.
Considerations for Selecting Transmitting Media
To maintain 100% availability and redundancy in industrial networks, the media you choose for data transmission should also be considered seriously. If the distance is less than 100 m, the best pick would be unshielded Cat5 cables. But if a single cable run is over 500 m, you should use fiber in the communication path, and if security tops the priorities, you should use fiber, too. The fiber optic cable is immune to both EMI and RFI, and since it does not radiate signals, it’ll be very difficult to tap without your knowledge. For distances over 2 km, go with single-mode fiber, and for distances between 500 m to 2 km, go with multi-mode fiber.
Industrial Managed Switches Recommendation
FASTCABLING has launched different types of industrial managed switches that suit most industrial applications where network redundancy is critical.