Why Industrial Managed Switch?
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| Industrial Unmanaged switches have been used for basic network connectivity in industrial networks. Although they are available with features such as redundant power inputs, wider operating temperature, and other hardware features that can be very important to applications but do not provide software features that are offered by managed switches. |
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| Industrial managed switches provide software features to increase performance and determinism to an Ethernet network by like features of QoS, IGMP Snooping, Redundancy, VLANs, and Traffic Monitoring. QoS or Quality of Service provides the ability to prioritize network traffic. |
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| QoS increases determinism by ensuring that high-priority traffic is passed through first. For example, frames to and from a motion controller would be processed before traffic to and from other devices |
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| IGMP Snooping provides smart routing of Multi-cast traffic. There are three types of transmissions over an IP network - Broadcast, Uni-cast, and Multicast. Broadcast traffic is data that is sent out to all devices on the network. Uni-cast messages are messages intended for one device, whereas multicast messages are packets sent to a predefined group of devices. Routers are aware of multicast messages being passed to and from the internet, or others networks, making multicast messaging more efficient than Uni-cast messaging. However, Switches are not aware of multicast traffic unless the IGMP snooping protocol is implemented. Without IGMP snooping, these messages become broadcast messages to impact and decrease network performances or even to bring network down. |
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| Redundancy reduces or eliminates potential downtime. When implementing industrial networks, downtime can be much more costly than with a typical commercial network. If an employee experiences a thirty-minute delay in receiving e-mail, it’s merely an inconvenience. If there is a thirty-minute gap in Industrial network, the consequences can be costly, even catastrophic. Redundant power inputs, for example, eliminate outages caused by a bad power supply, power outage, or faulty wiring. When the first power source becomes unavailable, the device automatically switches over to the second power source. Once power is restored, the device reverts to using the original source. Another type of redundancy is network redundancy. Managed switches can provide protocols such as the Rapid Spanning Tree Protocol or RSTP. However, recovery time of RSTP or STP is not quick enough to critical applications. In addition to STP and RSTP, LCSI Industrial Managed Switches provide proprietary redundant ring protocol called X-Ring which can recover within 20ms when link fails. |
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| VLANs allow a switch to logically group devices and to isolate traffic between these groups even if all the devices share a common physical switch. For example, if the switch was being used for both office communications and factory communications, two VLANs could be created to isolate the office communications from the factory communications. Some switches also allow devices to be located on multiple VLANs. This is sometimes called overlapping VLANs. If one device, a SCADA system for example, needs to communicate with both the office and the factory, then this device would exist in both the office VLAN and the factory VLAN. This would isolate traffic between the remaining office and factory devices, but allow the SCADA system to communicate on both networks. |
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| Traffic Monitoring provides the ability to view different types of transmission per port to ease troubleshooting of specific devices having communications issues |
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| The above-mentioned features are just a few samples of common features and protocols found in most managed switches. There are other features that may be available depending upon the particular switch that is being used. |
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| Several applications, such as IP video surveillance and many popular Industrial Protocols like Ethernet/IP, as well as many others, use multicast and/or broadcast messaging to increase performance. Multicast messages can be more efficient than Uni-cast messages, but can also increase network traffic. Without IGMP snooping, multicast messages essentially become broadcast messages which can decrease network performance, or possibly bring down the network altogether. IGMP Snooping helps reduce bandwidth and increase efficiency. |
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| It’s better to always use managed switches. Unfortunately, in the real world customer face obstacles such as budgets and price points. So, there is a trade-off. |
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