Switches include telephone switches (PBXs) and data switches (Switches). The switches we mentioned below refer to data switches, and we will not discuss traditional telephone switches.
In a broad sense, switches are divided into two types: wide area switches and LAN switches. WAN switches are mainly used in the telecommunications field and provide a basic platform for communications. Local area network switches are used in local area networks and are used to connect terminal devices, such as PCs and network printers. The following content is based on local area switches.
According to the most extensive general classification method, that is, from the perspective of scale applications, local area network switches can be divided into enterprise-level switches, department-level switches and workgroup switches. When serving as a backbone switch, switches that support large enterprises with more than 500 information points are enterprise-level switches, switches that support medium-sized enterprises with less than 300 information points are department-level switches, and switches that support less than 100 information points are working group-level switches. But this is not an absolute standard. It is precisely because there is no unified standard for division that concepts such as desktop switches and campus switches have emerged. Here is a brief introduction to the above concepts:
1. Desktop switch, which is the most common type of switch, is a feature that distinguishes it from other switches that supports few MAC addresses per port. It is widely used in general offices, small computer rooms, business departments with relatively concentrated business acceptance, multimedia production center, website management center and other departments. In terms of transmission speed, modern desktop switches mostly provide multiple ports with 10/100Mbps adaptability.
2. Workgroup switches are often used as expansion equipment. When desktop switches cannot meet the needs, most of them directly consider workgroup switches. Although the working group switch has only a small number of ports, it supports a large number of MAC addresses and has good expansion capabilities. The port transmission speed is basically 100Mbps.
3. Department switches, which are usually no more expensive than workgroup switches, and unlike workgroup switches, are different in number of ports and performance levels. A department switch usually has 8 to 16 ports, and usually supports full duplex operation on all ports. They perform better than a workgroup switch and have a half-duplex aggregate bandwidth equal to or exceed all port bandwidth.
4. Campus network switches, this kind of switch is relatively few, only used in large networks, and is generally used as the backbone switch of the network. It has fast data exchange capabilities and full duplex capabilities, and can provide intelligent features such as fault tolerance. It also supports expansion options and virtual local area network (VLAN) in layer 3 switching.
5. Although the enterprise switch is very similar to a campus network switch, the biggest difference is that the enterprise switch can also be connected to a large chassis. These chassis products generally support many different types of components, such as Fast Ethernet and Large Network Repeaters, FDDI Concentrators, Token Ring MAUs and Routers. Enterprise switches are very useful when building enterprise-level networks, especially for those that need to support some network technologies and previous systems. Chassis-based devices usually have very strong management characteristics and are therefore well suited for enterprise network environments. However, the disadvantage of chassis-based devices is that they are both very expensive.
According to the architectural characteristics, people also divide LAN switches into three types: rack-type, fixed configuration with expansion slots, and fixed configuration without expansion slots.
1. Rack switch This is a slot switch. This switch has better scalability and can support different network types, such as Ethernet, Fast Ethernet, Gigabit Ethernet, ATM, token ring and FDDI, etc., but it is expensive, and many high-end switches use rack structures.
2. Fixed configuration switch with expansion slot It is a switch with a fixed number of ports and a small number of expansion slots. This switch can also support other types of networks by extending other network type modules on the basis of supporting fixed port type networks. The price of these switches is at the center.
3. Fixed configuration switches without expansion slots. This type of switch only supports one type of network (usually Ethernet) and can be used in LANs in small business or office environments. It is the cheapest and most widely used.
From the perspective of transmission medium and transmission speed, LAN switches can be divided into Ethernet switches, fast Ethernet switches, Gigabit Ethernet switches, FDDI switches, ATM switches and token ring switches. These switches are suitable for Ethernet, Fast Ethernet, FDDI, ATM and token ring switches.
From the perspective of ISO/OSI hierarchical structure, switches can be divided into layer two switches, layer three switches, etc. Layer 2 switch refers to the switch that works on the second layer of the OSI reference model - the data link layer. The main functions include physical addressing, error verification, frame sequence and flow control. A pure second layer solution is the cheapest solution, but it provides the least control in terms of sub-network and broadcast restrictions. Traditional routers can also solve this problem when using them with external switches, but now the processing speed of routers can no longer keep up with bandwidth requirements. Therefore, layer three switches, web switches, etc. came into being.
A layer three switch is a device with layer three switching function, that is, a layer two switch with layer three routing function. However, it is an organic combination of the two, and it does not simply superimpose the hardware and software of the router device on the local area network switch.
Web switches provide management, routing and load balancing transmission for data center devices (including Internet servers, firewalls, cache servers, and gateways, etc.). Unlike traditional network devices, traditional network devices focus on completing the exchange of individual frames and data packets at high speed, while web exchange focuses on tracking and processing of web sessions. In addition to the connection and packet routing provided by traditional layer 2/3 switches, web switches can also provide complete strategies lacking in traditional LAN switches and routers, combining local and global server load balancing, access control, quality of service assurance (QoS), and bandwidth management capabilities. Currently, web switches have evolved from pure transport layer (layer 4) devices to intelligence with content-based (layer 7) switching. Redirecting web requests using content or user categories is a feature of the web server. However, the development of Internet transmission and commerce far exceeds the improvement of computer processing capabilities. Offloading content classification to a web switch balances the infrastructure of the entire website.
With the development of technology, more new nouns will surely emerge, but as long as you master the principles and have clear concepts, you will not be confused by them.