Network fault diagnosis, starting from the fault phenomenon, uses network diagnostic tools as a means to obtain diagnostic information, determine network fault points, find the source of the problem, eliminate the fault, and restore the normal operation of the network. Network failures usually have the following possibilities: failure of interconnection of physical devices in the physical layer or problems of hardware and lines themselves; interface configuration problems of network devices at the data link layer; network layer network protocol configuration or operation errors; equipment at the transport layer Performance or communication congestion issues; upper three layers or network application errors. The process of diagnosing network faults should proceed from the physical layer along the OSI seven-layer model. First check the physical layer, then the data link layer, and so on, trying to determine the failure point of communication failure until the system communication is normal. Various tools can be used for network diagnosis: router diagnostic commands, network management tools, and other troubleshooting tools including LAN or WAN analyzers. Checking the routing table is a good way to start finding network faults. ICMP's ping and trace commands and Cisco's show and debug commands are network tools for obtaining useful information for troubleshooting. How to monitor the details of the operation of the network under normal conditions and the occurrence of faults, and what to monitor? Using the show interface command, you can easily obtain information about each interface to be checked. The show buffer command provides regular display of buffer size, purpose, and usage status. The show proc command and show proc mem command can be used to track processor and memory usage. These data can be collected regularly and used for diagnostic reference when a fault occurs. Network troubleshooting steps The first step is to first determine the specific phenomenon of the fault and analyze the type of cause of the fault. For example, the host does not respond to customer requests for service. The possible cause of the failure is a host configuration problem, interface card failure, or router configuration command loss. The second step is to collect the required information to help isolate the possible causes of failure. Collect useful information from network management systems, protocol analysis tracking, router diagnostic command output reports, or software manuals. The third step is to consider the possible causes of failures based on the collected conditions and eliminate some of them. For example, based on certain information, you can troubleshoot hardware failures and focus on software causes. The fourth step is to establish a diagnosis plan based on the last possible cause of failure. At the beginning, only one of the most probable cause of the fault is used for diagnostic activities, so that the original state of the fault can be easily restored. If multiple failure causes are considered at once, it is much more difficult to try to return to the original state of the failure. The fifth step is to execute the diagnosis plan, carefully carry out each step of testing and observation, and confirm the result every time a parameter is changed. Analyze the results to determine whether the problem is solved. If not, continue until the fault disappears. Network fault diagnosis layered diagnosis technology The failure of the physical layer is mainly manifested in whether the physical connection mode of the equipment is proper; whether the connection cable is correct; whether the configuration and operation of Modem, CSU / DSU and other equipment are correct. The best way to determine whether the physical connection of the router port is intact is to use the show interface command to check the status of each port, interpret the screen output information, and view the port status, protocol establishment status and EIA status. To find and eliminate the fault of the data link layer, you need to check the configuration of the router and check the encapsulation of the connection ports that share the same data link layer. Each pair of interfaces must have the same encapsulation as other devices that communicate with it. Check the encapsulation of the router by viewing its configuration, or use the show command to view the encapsulation of the corresponding interface. The basic method to troubleshoot the network layer is to follow the path from the source to the destination, check the router routing table, and check the IP address of the router interface. If the route does not appear in the routing table, you should check to determine whether the appropriate static route, default route, or dynamic route has been entered. Then manually configure some lost routes or troubleshoot some dynamic routing processes, including RIP or IGRP routing protocols. For example, for IGRP routing, the selection information only exchanges data between systems with the same autonomous system number (AS) to check the matching of the autonomous system numbers configured by the router. 12V100Ah Lithium Ion Battery,Deep Cycle Solar Battery,2V 100Ah Lifepo4 Battery,12V 100Ah Lifepo4 Battery Pack Jiangsu Zhitai New Energy Technology Co.,Ltd , https://www.zttall.com
Network diagnosis is an important technical work to manage and use the network well so that the network can play the most role. This article briefly introduces the hierarchical diagnosis technology, discusses the diagnosis of various interfaces of the router, and summarizes the troubleshooting of the connectivity of the Internet.
It introduces how to diagnose and troubleshoot router network layering problems. I believe everyone will read this article to help you.