What is an Ethernet switch?
In recent years, accompanying rapid economic developments, innovation regarding repetitive technical operations pace faster day by day. Concepts such as Cloud Computing, Bring Your Own Device (BYOD), Software-Defined Networking (SDN), Internet of Things (IoT), video and big data emerged one after another and triggered demands for an Ethernet with higher density, higher performance, better agility and of larger scale, and thereby brought about a new wave of revolutionary growth in Ethernet Switching Technology.
The growing Ethernet Switch applications have become a major technical means for increasing the economic interests of industrial enterprises by realizing better quality, high productivity, and low power consumption.
What’s a Switch? What Purpose and Functions Does It Give?
What is a Switch
A switch is a networking device capable of transferring telecommunication signals. A switch provides an exclusive path of telecom signals between any two network nodes linked by the switch. The most popular is an Ethernet Switch; there are also telephone voice switches, optical fiber switches, and so on.
A switch that combines a phone-call carrying signal, switching class, control, command signals and other functions in a single unit is capable of connecting user wires, telecom circuits and other functional units that need to be connected together in accordance with exclusive user requirements.
Switching refers to the automated transmission of specific data to a corresponding router, manually or using devices, based on the needs of the two communicating ends. A switch, in general meaning, is the device capable of exchanging data in a communication system.
Difference between a Switch and a Hub
The invention of switching technics changed the previous working mode that used a common HUB, therefore substantially improving transmission efficiency of computers in the network system. HUBs cannot differentiate destination addresses, therefore, in a HUB configured network, when machine A transmits data to machine B in the same domain and the packet is sent by broadcast, every terminal will have to confirm its reception by verifying the header bit of the packet.
That is to say, this working method only supports the communication when only one data frame is transmitted in the network at a time; a re-try will be needed if any collisions occur.
Action and Function of a Switch
The main functions of switch include physical address, network topology, error check, frame sequence and flow control; switches are also capable of completing operations such as learning, forward / filter, and elimination loop, etc.; new switches even support functions like VLAN, link aggregation, or even firewall.
Learning: MAC address table of an ethernet switch registers bit addresses of devices linked at every port; it also stores port mapping corresponding to bit addresses.
Forward / Filter: After mapping the destination address of the data frame into the MAC table, the data frame will be forwarded to the port of the linked destination node instead of to all the ports (except for broadcast/multicast frames).
Elimination Loop: An Ethernet switch can eliminate redundant circuits included in the switch by using spanning-tree protocol; it also permits the existence of a standby path.
In addition to connecting the same type of network, a switch can also accomplish interlinking of different network types (such as linking Ethernet and Fast Ethernet). Currently, many switches provide high-speed ports supporting Fast Ethernet or FDD, used for linking other switches in the network and additional bandwidth of key servers that occupy a large bandwidth.
In general, every port of a switch corresponds to an individual network segment. However, in special conditions, we may connect some important computers within the network directly to a port switch. Key servers and important users in the network may get faster connection speeds to support even higher data flow.
Let’s summarize the basic functions of a switch:
- A switch provides a large number of cable ports for adopting Star Topology Routing.
- When forwarding frames, the switch re-generates a distortion-free square electrical signal.
- All the ports of a switch are of the same forward or filter logic.
- A switch substantially increases the bandwidth of a local area network (LAN); it divides LAN into several conflict areas, each having an independent bandwidth.
- In addition to the functions of bridge, hub and relay, a switch also provides advanced functions such as virtual local area network (VLAN).
Differences between an Industrial Class Switch and a General Commercial/Domestic Switch
Based on applications, general switches are mainly categorized as ordinary and industrial. As suggested by the names, industrial switches refer to the ones used in an Ethernet network for industrial production. In contrast, ordinary switches refer to networking switches used in commercial and domestic networks. So how do we differentiate between them and what are their relative advantages?
Just like differences between PCs and industrial control computers, an industrial switch has no intrinsic differences from an ordinary switch. They are all identical in the data linkage layer, the networking layer, and the protocol layer. However, an industrial Ethernet switch has resolved technical issues addressing real-time communication requirements regarding industrial controls as well as network security, intrinsic safety and explosion-proof provisions; it also possesses features adaptable to industrial environments such as waterproof and vibration-proof resistance.
Differences in Appearance
Industrial switches are generally equipped with high-strength metal casings in a fanless heat dissipation construction. Ordinary switches are mostly made with plastic housings and are fan cooled.
Application environments are not exactly the same
For industrial switches, working temperatures range from -40°C to 85°C. Insulation protection class is IP40 or higher with exceptional dust and humidity prevention capabilities, Power over Ethernet (POE) function is supported; they adapt to extensive application scenarios and can be installed in extreme environments for normal operation. As for ordinary switches, working temperatures range from 0°C to 50°C, the protection level is relatively low and they are seldom dust or humidity proof. In addition, Power over Ethernet (POE) function is usually not supported.
Service Life Differences
Industrial switches have a service lifespan of at least 10 years; ordinary switches only 3-5 years. Since the service life of devices is decisive to maintenance requirements during the engineering period, Industrial switches, or industrial equivalent ones, should be selected for parks, office buildings, parking lots and other environments having video surveillance networks where high-definition video output is a necessity.
Other Reference Indexes
The voltage used by Industrial Switches is different from that of ordinary switches. Industrial switches may be limited to DC24V, DC110V, AC220V, or multiple voltage values; Ordinary switches can only work with AC220V voltages. Furthermore, industrial switches are mostly configured in ring network mode. Therefore, they reduce the costs of circuit utilization and maintenance.
Different Installation Methods
Industrial Ethernet switches generally use DIN rails and racks for installation; ordinary switches are usually racked and desktop installed. Why should proper industrial Ethernet switches be used in industrial sites instead of less expensive commercial switches?
The necessity for using Industrial Ethernet switches in industrial sites can be assured by the following:
The MAC layer Ethernet protocol of the CSMA/CD protocol allows conflicts in the network, especially when network loading is excessively high. When a large number of conflicts exist in an industrial network, multiple resent data will occur, substantially increasing communication uncertainty within the network. In an industrial control network, such uncertainties from one place to another will diminish control performance of the system.
The concept of real-time in the industrial control system refers to the measurable reaction time of the system against a certain event. In other words, it means the system must respond within a foreseeable range of time when an event occurs. The industry has strict requirements in regard to real-time data transmission; data updates must be accomplished within a few tens of milliseconds.
Based on the aforementioned mechanism of Ethernet CSMA/CD, data needs to be resent (maximum 16 times) when conflicts occur and this will take more time. In the event of a drop of line signal, even for just a few seconds, the entire production may be brought to a stop, even resulting in safety incidents of both equipment and personnel.
In the beginning, Ethernet design was not purposed for industrial applications. Therefore, when used in industrial sites, harsh working conditions as well as severe inter-line interferences would all lead to diminished reliability. In production environments, if the industrial network lack's adequate reliability, and maintainability, failure of the application program, OS or even the networking system would be triggered when any component in the network fails.
Complicated conditions of worksites have been considered at the very beginning of Industrial Ethernet switch design for further adaptation to industrial environments and better functionality.
Summary: Whether looking at it from aspects of components; power supply design; or heat dissipation methods, the properties of industrial Ethernet switches are much better than ordinary switches.
Managed vs Unmanaged – how do users select the most applicable product
Features of Managed Switches
Switches can be divided into ordinary and network-managed. Ordinary switches require no setting; they can plug and play. Network-managed switches include Layer-2 switches and Layer-3 switches. Layer-2 switches feature multiple functionalities such as VLAN, spanning tree, access-list, etc.; Layer-3 switches are capable of accomplishing router tasks in addition to functionalities of a Layer-2 switch, so are usually the core switch in a local area.
As their name suggests, a network-managed switch refers to a switch capable of performing network management. Network-managed switches provide various methods for network management, including remote login based on the terminal control port, webpage, network management software and Telnet. They are capable of performing multiple network management functions including monitoring switch ports, zoning VLANs, setting up trunk ports, etc. Local or remote real-time surveillance on switch working status and network operation conditions can be carried out via background network management, thereby comprehensively overviewing working status and working modes of all the switch ports.
Network-managed switches feature multiple network management functions such as VLAN, CLI, SNMP, IP routing, QoS, etc., therefore they have more advantages in actual applications than ordinary switches.
Supports complicated network applications
Network-managed switches allow the network manager to prioritize data transmission sequences based on types of data, providing comprehensive QoS support to real-time network applications like video conferences and IP phone calls. In a network configured with ordinary switches, data flow cannot adapt to multimedia or special networking applications; data of any type has to queue for transmission.
Increased Network Stability
Via spanning tree and EtherChannel technologies, network-managed switches not only can accomplish linkage of redundancy but can also double the linking bandwidth between devices (switch and switch, switch and router, switch and server), thereby balancing networking load and ensuring the stability of network operations. Ordinary switches, if configured with redundancy, will result in a paralyzed network due to the existence of ring topology. Still, without redundancy, communication of a part of the network, or even the entire network, may be interrupted when any of the wiring, devices or modules fail.
Improved Network Security
Compared to ordinary switches having no network security features, network managed switches have more outstanding performances in securing data storage and safe visits; they are capable of isolating networks of different departments by way of various methods like VLAN, Private VLAN (PVLAN) and Access Control List (ACL), to refuse visitation to sensitive information by specific users. Furthermore, via the listing of visits, propagation of worm-type virus can be effectively prevented, assess rights of certain users can be prohibited, and network safety can be further secured.
Improved Network Transmission Efficiency
When there are sufficient numbers of computers and communication protocols in the network, many broadcast packages will be generated and severely affect the transmission efficiency. Ordinary switches can only differentiate collision areas, not broadcast areas. Therefore, a single network structure shall accommodate no more than 150 computers. While network-managed switches, via VLAN function, can divide a network into several logical subnets, thereby minimizing the broadcasting range and lifting the transmission efficiency of the entire network.
Supports Remote Monitoring and Management
For a medium to large scale network, it is of equal importance regarding remote monitoring, layout, and management of the switches. Network managed switches, when allocated an IP bit address, may easily realize all these functions. The network manager may manage all the switches in the network, become aware of their operation status, and modify switch allocations based on needs just by sitting in front of their computer. Network-managed switches effectively lower the difficulty and intensity of network management. They not only carry out centralized management via network management software, but can also stack several switches for constituting a single management switch.
Features of Unmanaged Switches
Unmanaged switches only have simple data forwarding functions and can perform no network management tasks. These Ethernet switches do not process the data directly, therefore require no setting and are plug-and-play enabled. Unmanaged switches are also called ordinary switches. Specifically, unmanaged switches have the following features:
- No setting required; plug-and-play Neither professional specialist nor tedious training is required; large amounts of manpower and costs can be saved.
- No compatibility issues No software or maker design limitations; all standard IEEE unmanaged Ethernet switches can be smoothly merged into networking environments of all kinds with no compatibility issues.
- Fast deployment; flexible scalability Benefiting from the above 2 features, users are enabled to expand or downscale networking configuration promptly.
- Low price
- Intensive quantity of ports
- User agility
How do users select optimal products
To ensure smooth operation of the entire network system, selecting a most suitable switch model is of great importance; then, how do we choose between network-managed switches and unmanaged ones?
- When used in large-scale network environments, choose network-managed switches. They are powerful, full of functions, steady, and easy to maintain, and they can achieve Ring Topology connection.
- For domestic or small network applications, choose unmanaged switches; they are plug-and-play enabled, easy to manage, and cost less.
- When purchasing switches, an enterprise needs to select a switch based on its project requirements. In general, network-managed switches and unmanaged ones are both necessary.
Features of Advantech Switch Products
All Advantech Ethernet Switches are industrial grade that meet requirements of various harsh industrial environments and ensure that products work continuously and reliably. Furthermore, this comprehensive product line covers all application requirements for a multitude of application domains.
EKI-2000 Unmanaged Industrial Ethernet Switch
Designed exclusively for industrial environments, it provides high efficiency, reliability and value. Requires no further settings; real convenience with plug and play. It provides standard 10/100Mbps and Gigabit 10/100/1000Mbps for copper cable and optical fiber connections. Super thin IP30 metal casing provides high reliability for successive high-speed transmission and is the ideal choice for Ethernet solutions.
EKI-5000 Industrial Protocol Featherweight Ethernet Switch
Compatible to SIMATIC step 7 and TIA portal (PROFINET compatible) • PROFITNET supports Media Redundancy Protocol (MRP) • Panel compatible to Rockwell FactoryTalk View (Ethernet/IP compatible). Advantech IXM Technology for easy and quick deployment. Key functions embedded (multi-function protocol switch)
EKI-7000 Industrial Ethernet Switch
Allows users to expand their industrial network rapidly and cost-effectively; the robust industry class design ensures reliability and stability. Furthermore, Advantech’s X-Ring technology provides a fast recovery time (<10ms) that escalates the reliability and speed of the fundamental network structure.
EKI-9000 EN50155, Switch for rail-traffic applications
EN50155 certified and impact and vibration resistant, this product ensures reliable transmission of on-board trunk Ethernet communication. This switch is designed for applications having multiple Ethernet switches, such as video monitoring, car status monitoring, and chair-back entertainment systems of high-speed rail, electric streetcars etc.
Advantech WebAccess/NMS is a fundamental webpage browser package for the network management systems (NMS); adapting SNMP and ICMP communication protocol, WebAccess/NMS is capable of managing all Ethernet-based Advantech products and supplier devices.
WebAccess/NMS provides a simple and easy-to-use platform for the user to remotely monitor and manage the network. Capable of industry class centralized network management, the consolidated platform is developed to provide a path to IP-based monitoring, setting, and maintenance devices.