With the development of information network technology, from the Internet to the current Internet of Things, there are more and more network equipment. Whether a LOCAL area network (LAN), metropolitan area network (MAN), or wide area network (WAN), a physical network consists of network connection devices and transmission media such as network adapters, hubs, switches, routers, network cables, and RJ45 connectors. Network equipment and components are connected to the network in the physical entity, a wide range of basic network devices have a "computer (either PC or server), Repeaters, hubs, routers, switches, firewalls, Bridges, gateway, network card (NIC), printer, modem, optical transceiver, optical cable", etc.
Today, we will pick some basic, common network equipment, briefly explain and introduce.
I. Server
The server is the most important device on a computer network. A server is a device that runs corresponding application software in a network environment and provides users with shared information resources and services. The structure of a server is similar to that of a PC (PERSONAL computer), including processor, memory, hard disk, network adapter, and system bus. However, a server is specially designed for specific network applications, so there are great differences between a server and a PC (PERSONAL computer) in processing capacity, stability, reliability, security, scalability, manageability and other aspects.
Typically, servers have more processing power, more memory, and more hard disk space than PCS. The network operating system on a server can not only manage data on the network, but also manage users, user groups, security groups, and applications.
The server is the center of the network and the core of information. It has the characteristics of high performance, high reliability, high availability, strong I/O throughput, large storage capacity, and strong networking and network management capabilities.
The classification standard of the server is more diversified. It can be divided into "entry level, working group level, department level and enterprise level" according to the application level. According to the architecture, it can be divided into x86 servers and non-x86 servers. According to the instruction system used by the server, it can be divided into CISC (complex instruction set), RISC (simplified instruction set), VLIW (ultra-long instruction set). Divided by use, can be divided into "general type and special type"; Servers are classified into tower servers, rack servers, cabinet servers, and blade servers based on their chassis architecture.
Server selection:
1, the performance should be stable. In order to ensure the normal operation of the network, the selected server must first ensure stability. On the other hand, a stable server means a company can save money on maintenance.
2, to consider the scalability, in order to reduce the extra cost of updating the server and the impact on the work, the server should have a high scalability, can timely upgrade or adjust the configuration to adapt to the development.
3, easy to operate and manage.
4, can meet special requirements.
5, the hardware collocation should be reasonable. To make the server run more efficiently, ensure that the performance of the internal components of the server purchased must be properly matched.
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Two, repeater
Repeaters can be used to connect different physical media and transmit data packets over various physical media. Some multi-port Repeaters, much like multi-port hubs, can connect different types of media.
Repeaters are the cheapest way to extend a network. When the purpose of extending the network is to break through the limits of distance and nodes, and the connected branches of the network do not generate too much data traffic, and the cost is not too high, the choice of repeater can be considered. The number of network branches connected by repeater is limited by the specific network architecture.
The repeater has no isolation or filtering capabilities, and it cannot block packets containing exceptions from passing from one branch to another. This means that if one branch fails, it can affect every other branch of the network.
A hub is a repeater with multiple ports, referred to as a hub.
Third, the bridge
A bridge that operates at the data link layer of the OSI (Open Interconnected System) system. Therefore, information from the OSI data link layer above is of no use to the bridge. So understanding the protocol depends on the respective computer.
A bridge contains the functionality and features of a repeater that not only connects multiple media, but also connects different physical branches, such as "Ethernet" and "token network", to transmit packets over a larger area. A typical application of a bridge is to divide a LAN into subnets to reduce the bottleneck of data transmission. Such a bridge is called a "local" bridge, and a bridge for a wide area network is called a "remote" bridge. The two types of Bridges perform the same function but use different network interfaces.