Chapter 3 Network Troubleshooting

l l l l CHAPTER 3 NETWORK TROUBLESHOOTING Upon completing this chapter, you should be able to do the following: Describe how to diagnose and isolate problems with LANs. Describe how to troubleshoot network malfunctions. Explain how to test and evaluate the connection of networking system nodes. Explain how to troubleshoot communications line problems. With any network system, you should have a set of error procedures for personnel to follow to handle errors or malfunctions on the system. These error procedures are the steps to be taken when the system is not operating properly. They are different from the error- detection and diagnostic procedures used to isolate and correct transmission problems. A complete set of diagnostic procedures is necessary for the system. The system procedures are used to isolate the problem to the system or subsystem level. Since the facilities of a network may not be in the local area, it is necessary to have a set of test software and equipment with replacement components available for diagnosing and correcting problems. TROUBLESHOOTING LANS As a communications specialist, more than likely you will be expected to know how to troubleshoot problems on LANs. As a troubleshooter, you must be able to identify a wide range of network problems relating to hardware (the data terminal equipment, the communications link, repeaters, gateways, and so on), software (network operating system, applications, and soon), and peopleware (the end user). It will be your job to identify, isolate, and resolve both the simple and complex problems. DIAGNOSTIC TOOLS Normally, a problem can be solved without too much difficulty with the help of diagnostic tools. The best diagnostic tool available is accurate documentation. This documentation should include: l l l l Workstation and server configurations All network related software and equipment Location and paths of all wiring Updated records of all equipment and configurations changes With documentation in hand, along with the help of diagnostic software (a network management package or a LAN analyzer), and specialized diagnostic equipment, such as a datascope, a time domain reflectometer (TDR), or a breakout box, the job becomes routine. Classifying the problems and taking the necessary actions to resolve them are an important part of your job as a troubleshooter. However, it is equally important to remember to log all problems according to your activity’s procedures. This will identify recurring problems, provide information for long term solutions, and enhance your command’s training program. ISOLATING PROBLEMS When isolating a problem, consider the three major areas we discussed earlier-the user, the software, and the hardware, usually in that order. The majority of all network-related problems are caused by the user’s actions—operator errors. Users either do not understand how to operate their PC in a networking environment or they are unfamiliar with the application software package they are using. Most of the time you will find yourself responding to user problems and complaints. A user will call, saying such things as the following: 3-1