Industrial Switch (IndustrialSwitch), also known as Industrial Ethernet Switch, is a kind of network equipment working on OSI layer 2 (data link layer, see "WAN" definition), based on MAC (medium access control address of the network card) identification, and able to complete the function of encapsulating and forwarding packets. What are the functions of an industrial switch?
Industrial switches have automatic addressing capabilities and switching roles by regenerating information and forwarding it to designated ports after internal processing. All ports on an industrial switch have exclusive channel bandwidth to ensure fast and efficient data transmission on each port. Since the industrial switch sends each information packet independently from the source port to the destination port according to the destination address of the delivered information packet without sending it to all ports to avoid conflict with other ports, the industrial switch can transmit these information packets at the same time without interfering with each other and preventing transmission conflicts, which improves the actual throughput of the network.
There is no essential difference between industrial Ethernet switch itself and commercial network in terms of data link layer, network layer, protocol layer, etc. However, for the real-time demand of industrial control, industrial Ethernet solves technical problems such as real-time communication, network security, intrinsic safety and explosion-proof technology, and adopts some measures suitable for industrial environment, such as waterproof and vibration-resistant. Its core is still not essentially different from commercial Ethernet, which is the same as the difference between PCs and industrial controllers.
I. Network Security
In advanced industrial applications, network security has become a problem to be solved. And many domestic manufacturers (such as Dongtu, Mosa, Maverick Communications, etc.) produce Web-managed series of industrial switches for the LAN in the network security issues provide a variety of features.
1. Password - with multi-level user passwords to avoid unauthorized access and settings.
2.Enable/DisablePortsOpen and Close Ports-Turns unused ports off.
3.802.1qVLAN-Predefined WLAN on industrial switches to achieve logical isolation between physical ports.
4.802.1xPort-based Network Access Control - locks down ports on an industrial switch so that only legitimate users are allowed to communicate.
5.MACBasedPortSecurity MAC address-based port security - protects the ports of industrial switches so that they can only communicate with specific devices or MAC addresses.
II. Port Device Status
Set the rate, duplex, auto-negotiation, and flow control of each port to establish a correct connection with devices that cannot negotiate or have specific settings.
III. Port Rate Limiting
Configure the rate limiting of ports, including ingress and egress speed limiting. The types of port restrictions include all unicast packets, multicast packets, and broadcast packets. Where ingress speed is the actual speed of the flow from other devices such as PCs to the industrial switch port. The egress speed is the actual speed of the flow from the industrial switch port to the device using it between. If both the ingress and egress speeds between two device-connected ports are limited, the actual speed is the smaller of the two values.
IV. Storm Suppression Storms
wreaks havoc on the network and causes network-connected devices to fail. In business-critical applications, it can be catastrophic. Filters broadcast packets according to user-defined limits to suppress storms.
V. Quality of Service QualityofService (IEEE802.1p)
Industrial switches incur delays when the network is heavily loaded due to the frame buffer queue and first-come-first-served mechanism.IEEE802.1p allows packets in a high priority queue to stay in the industrial switch for a shorter period of time, and the opposite is true for packets in a low priority queue.
VI. Virtual Local Area Network VLAN (IEEE802.1q)
Virtual Local Area Network (VLAN) is a method of creating separate logical networks from an actual physical network, which enables several virtual LANs to exist in an actual physical network at the same time.VLANs can effectively reduce the broadcast range, which is convenient for network management. In fact, if a router is added between these different virtual network segments, data can still be exchanged between them through the router.VLANs can effectively inhibit the occurrence of broadcast storms.
VII. Multicast Listening IGMPSnooping
A Layer 2 device running IGMPSnooping analyzes received IGMP messages to establish a mapping relationship for port and MAC multicast addresses and forwards multicast data based on such a mapping relationship. When a Layer 2 device does not perform IGMPSnooping, multicast data is broadcast at Layer 2; when a Layer 2 device runs IGMPSnooping, multicast data for a known multicast group is not broadcast at Layer 2, but is multicast at Layer 2 to the specified receiver.
VIII. Fast Ringing (MW-Ring)
MW-Ring allows industrial switches to be connected to each other with redundant links, so that when one of them is disconnected, the other link can be quickly and automatically restored. In case of network interruption or network failure, it has link redundancy and fast self-recovery ability.MW-Ring technology is developed and designed by Wuhan Meinweg Communication Co., Ltd. specializing in high-reliability industrial control network applications.
IX. Link Aggregation (802.3ad)
The main function of port aggregation (TRUNK) is to bind multiple physical ports (generally 2-4) into a logical channel so that they work as one channel. After bundling multiple physical links together, it not only enhances the bandwidth of the entire network, but also allows data to be transmitted simultaneously through multiple physical links that are bound, which has the effect of link redundancy, and in the event of a network failure or other reasons for disconnecting one or more of the links, the remaining links can still work.
X. Rapid Spanning Tree RSTP
Spanning Tree Protocol is a Layer 2 management protocol, which selectively blocks network redundant links to eliminate the purpose of network Layer 2 loops, as well as the backup function of the link.
XI. Port-based Network Access Control (802.1x)
Defines a port-based network access control mechanism that provides a method of identifying and authorizing devices connected to a LAN port.
XII.HTMLWeb Browser
Provides a simple, intuitive user interface for setup and monitoring via a standard graphical web browser. All system parameters, including detailed online help makes setting up the system a breeze.
XIII. SNMP (Simple Network Management Protocol)
Simple Network Management Protocol (SNMP) defined by the Internet Engineering Task Force, is part of the composition of the Internet protocol. In the conditions of concern for a particular network device, the use of SNMP through the network management system to monitor network devices. SNMP protocol consists of a series of standard network management, application layer protocols, databases, data objects.
XIV. Port Mirroring
Port mirroring function is to send and receive all the data of one or more ports, copy to the specified other port. By designating a port as the mirror port of other ports, you can observe all the incoming and outgoing data of other ports through this port. Troubleshooting, debugging and analyzing the network through the port mirroring function.
XV. Port Statistics and Remote Monitoring (RMON)
Each port provides continuously updated statistics, including all incoming and outgoing packet counts and byte counts, as well as detailed error statistics. All support for RMON statistics, history, alarms, and event groups is also provided.RMON accomplishes accurate data collection, analysis, and detection of data flow models.
XVI.NTP (Simple Network Time Protocol)
Automatically synchronize the system's internal clock with the NTP server in the network, thus providing time correlation of events for fault analysis.
XVII. Event Logging and Alarming
Records all significant events into a non-volatile system log for future failure analysis. Events include link failure and recovery, illegal access, broadcast storm detection, and self-test diagnostics. Alarms provide a snapshot of the latest events that have occurred and have not been responded to by the network administrator. An external hardware relay releases contacts during critical events, allowing the external controller to operate when necessary.