What are LAN and WAN?

A local area network (LAN), referred to as LAN, is a dedicated network in the same building, the same university, or a few kilometers away. LANs are often used to connect personal computers and workstations in corporate offices or factories to share resources (such as printers) and exchange information. String 2

What is a metropolitan area network

Metropolitan area network (metropolitan area network), or MAN, is basically a large LAN, usually used in LAN-like technology. It can cover a group of adjacent corporate offices and a city, and may be either private or public. MAM can support data and voice, and may involve local cable television networks. MAN uses only one or two cables and does not contain switching units, equipment that splits packets into several possible outgoing cables. Doing so simplifies the design.

- The main reason for classifying MAN as a separate category is that a standard already exists and is being implemented. This is distributed queue dual bus DQDB (distributed queue dual bus). For those who are used to using numerical codes, it is 802.6 (the IEEE standard number defined by it). DQDB consists of two unidirectional buses (cables) to which all computers are connected. As shown in the figure, (P8-1-4) each bus has a head-end, which is a device that initiates transmission activities. The upper bus is used when the destination computer is to the right of the sender. Otherwise, use the lower bus.

- The key to MAN is the use of broadcast media (802.6, using two cables), to which all computers are connected. It greatly simplifies design compared to other types of networks. String 3

What is a wide area network

A wide area network (wide area network), or WAN, is a network that spans a large area, usually including a country or state. It contains the collection of machines on which you want to run user (i.e. application) programs. As shown in the figure (P9-1-5), we call these machines hosts according to traditional usage. Sometimes called an end system. Hosts are connected through communication subnets (or subnets for short). The function of a subnet is to carry messages from one host to another, much like a telephone system carries sounds from the speaker to the receiver. By separating the purely communication part of the network (subnets) from the application part (hosts), the overall network design is simplified.

- In most WANs, a subnet consists of two distinct components, the transmission line and the switching unit. Transmission lines, also called circuits, channels, and trunks, carry bits between machines. String 5

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Divided according to network size, distance and structure: local area network, metropolitan area network, wide area network

String 2

LAN (Local Area Network): Generally not larger than 10 kilometers, and usually only uses one transmission medium; geographically, LAN is usually used in a building or a factory, and is usually used by a certain unit Or used by a certain department, and the scale generally does not exceed a few hundred users.

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MAN (Metropolitan Area Network): A metropolitan area network is a larger network than a local area network, usually covering a city, ranging from dozens of kilometers to It can range from 100 kilometers, there may be a variety of media, and the number of users is more than that of a local area network. s string 7

WAN (Wide Area Network): All networks larger than the metropolitan area network can be called wide area networks. Different local area networks, metropolitan area networks or wide area networks can also be linked to each other as needed to form a larger international network. What we usually call the Internet is built based on this idea.