Knowledge of computer network and router fault diagnosis

Router fault diagnosis is a comprehensive technology, which involves various aspects of network technology. Let's take a quick look at the basic concepts of networking and routers.

First, computer network

The development of computer network leads to various forms of connection between networks. Computer networks are usually divided into LAN and WAN according to the distribution range of their computers. Wide area network covers a large geographical range, such as campuses, cities, and even around the world; the local area network covers a small geographical range, usually between several meters to dozens of kilometers.

Computer network is a system composed of computers and communication facilities, that is, the use of various means of communication, geographically dispersed computers together to achieve mutual communication and sharing software, hardware and data resources such as the system.

Second, the Internet

The interconnection of different networks is realized by unified protocol, which makes the Internet easy to be expanded. The internet is the network that completes the connection between networks in this way. The Internet uses the TCP/IP protocol as the communication Protocol, which connects the computer network in the world and becomes the largest and most popular international network in the world today.

In order to complete communication between computers, the function of each computer interconnection is divided into well-defined level, which stipulates the protocol of the same layer process communication and the interface and service between the adjacent layers, and the interface between these layers, the protocols of the same layer process communication and the neighboring layers is called the network architecture.

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The Open Systems Interconnection Reference Model (OSI) proposed by the International Organization for Standardization (ISO) is the core of the modern computer network technology system. The model divides the network function into 7 levels: Physical layer, Data link layer, network layer, transport layer, Session layer, presentation layer and application layer.

Third, TCP/IP is the Transmission Control Protocol

TCP/IP, the Transmission Control protocol, and the internetwork interconnection protocols are a set of network protocols. TCP/IP originated in the United States ARPANET Network, the development has become the use of the Internet Standard communication protocol. Using TCP/IP enables computers with different operating systems to exchange data in an orderly fashion.

Four, routers

A router is a network device that is a dedicated computer for network connections and performing routing tasks. The router works on the network layer, forwards the packet and has filtering function. Router fault diagnosis enables the interconnection of two networks that use different technologies to establish network connectivity across multiple types of networks (LAN or WAN).

It will be in the seven-tier model of the network layer of information, according to the fastest, most direct routing principle from one network layer to another network layer, to achieve the best routing choice. At the same time in the internal use of high-end microprocessors, with high-speed internal bus connection for a variety of network protocol interface card. and has a variety of network management functions, can monitor and router fault diagnosis of a number of connected networking devices and their configuration operation.

Five, Cisco router

Cisco router is one of the most used routers in network construction at present, it has many grades, many series, and is currently used in 2500 series, this article takes 2500 series as an example to discuss. The 2500-Series router is a multi-protocol router with a fixed interface that supports all Cisco IOS features. The specific protocol environment is divided into the following four types: fixed-configured router troubleshooting (2501), router with hub port (2507), touch-block Router (2514), and Access server (2511). They are simple in structure, easy to operate, easy to configure and manage, and are used as routing devices for small scale LAN and WAN network layer relay.

CISCO iOS has become the de facto standard for industrial Internet interconnection. CISCO iOS offers several different modes of operation, each of which provides a set of related sets of commands, different operational permissions, and operational capabilities. For security purposes, there are two levels of access in the Cisco user interface: User-level and privilege-level.

First-level access allows you to view the routing state, called user exec mode, also known as view mode, and second level access allows you to view router troubleshooting, modify configuration, and run debug commands, called Privileged exec mode, also known as configuration mode. In the privilege level, depending on the configuration content, you can enter different configuration modes, such as global configuration mode, interface configuration mode, line configuration mode and so on.

The above is the network and router fault diagnosis knowledge, through this understanding we can know the router fault diagnosis method, so as to solve the problem.