Topic 6-Network Troubleshooting 1 Network Troubleshooting Tools 2 Physical Troubleshooting

1. Topic 6-Network Troubleshooting • 1 Network Troubleshooting Tools • 2 Physical Troubleshooting • 3 Data Link Troubleshooting • 4 Network Services Troubleshooting

2. 1 Network Troubleshooting Tools Network administrators use a number of tools for searching out network problems. The following list details some of these tools: a) Protocol Analyzers. These hardware or combined hardware and software products are used to monitor network traffic, track network performance, and analyze packets. Protocol analyzers can identify bottlenecks, protocol problems, and malfunctioning network components b) Network Monitors. These software-based tools monitor network traffic, displaying packet information and keeping statistics on network usage c) Digital Volt Meter (DVM). This hand-held electronic measuring tool enables you to check the voltage of network cables. You can use a DVM to help you find a break or a short in a network cable. d) Time-Domain Reflectometer (TDM). TDMs send sound waves along a cable and look for imperfections that might be caused by a break or a short in the line. e) Oscilloscope. This device measures fluctuations in signal voltage and can help find faulty or damaged cabling.

3. 1. 1 Explain the common problems in a network system. • Most network problems occur out on the wires. The components that connect PCs and enable them to communicate are susceptible to many kinds of problems. • For examples of these externel equipmnet such as cabling, devices, and some electronic parts have the most high potential to malfunction within several periods. • This situation might happens causing of the environment of devices placed or from some geographical changes made by some individuals. i) Cables and connectors Ii ) Network adapter cards Iii ) Hubs and MSAUs iv) Modems • The most systematic way to approach solving problem in a network is by using the documentation. • Every network design should be implemented together with the documention from the cabling to system. This will help for future maintenance and troubleshooting. • It also a method of recording every activities and problems that can be review in the future by new employee or administrators to work in efficient. 

4. 2 Physical Troubleshooting 2.1 Troubleshooting Cables and Connectors • Most network problems occur at the OSI Physical layer, and cabling is one of the most common causes. A cable might have a short or a break, or it might be attached to a faulty connector. Tools such as DVMs and TDRs help search out cabling problems. If a workstation cannot access the network, and you think the problem might be the cabling, try disconnecting the network cables and attaching them to a portable PC. If the portable reaches the network, cabling probably isn’t your problem.When troubleshooting any network, begin with the more obvious physical problems. For example, make sure that all connectors are tight and properly connected, that ground wires and terminators are used when required, and that manufacturer’s specifications (such as cable grade, cable lengths, and maximum number of nodes) are met and are consistent with the specifications for the transmission medium.

5. 2.2 Troubleshooting Network Adapter Cards • Network problems often result from malfunctioning network adapter cards. The process of troubleshooting the network adapter works like any other kind of troubleshooting process: start with the simple. The following list details some aspects you can check if you think your network adapter card might be malfunctioning: • Make sure the cable is properly connected to the card. • Confirm that you have the correct network adapter card driver and that the driver is installed properly . Be sure the card is properly bound to the appropriate transport protocol. • Make sure the network adapter card and the network adapter card driver are compatible with your operating system. If you use Windows NT, consult the Windows NT hardware compatibility list. If you use Windows 95 or another operating system, rely on the adapter card vendor specifications. • Test for resource conflicts. Make sure another device isn’t attempting to use the same resources . If you think a resource conflict might be the problem, but you can’t pinpoint the conflict using Windows NT Diagnostics, Windows 95’s Device Manager, or some other diagnostic program, try removing all the cards except the network adapter and then replacing the cards one by one. Check the network with each addition to determine which device is causing the conflict. • Run the network adapter card’s diagnostic software. • If necessary, remove the card and clean the connector fingers (don’t use an eraser because it leaves grit on the card). • Examine the jumper and DIP switch settings on the card. Make sure the resource settings are consistent with the settings configured through the operating system. • Make sure the card fits properly in the slot. • Replace the card with one that you know works. If the connection works with a different card, you know the card is the problem.

6. 2.3 Troubleshooting Hubs and MSAUs • If you experience problems with a hub-based LAN, such as a 10BASE-T network, you often can isolate the problem by disconnecting the attached workstations one at a time. If removing one of the workstations eliminates the problem, the trouble may be caused by that workstation or its associated cable length. If removing each of the workstations doesn’t solve the problem, the fault may lie with the hub. Check the easy components first, such as ports, switches, and connectors. Then use a different hub (if you have it) and see if the problem persists. If your hub doesn’t work properly, call the manufacturer.

7. 2.4 Troubleshooting Modems • A modem presents all the potential problems you find with any other device. You must make sure that the modem is properly installed, that the driver is properly installed, and that the resource settings are consistent and do not conflict with other devices. Modems also pose some unique problems because they must connect directly to the phone system, they operate using analog communications, and they must make a point-to-point connection with a remote machine. The online help files for both Windows NT and Windows 95 include a topic called the Modem Troubleshooter . The Modem Troubleshooter leads you to possible solutions for a modem problem by asking questions about the symptoms. As you answer the questions (by clicking the gray box beside your answer), the Modem Troubleshooter zeroes in on more specific questions until (ideally) it leads you to a solution.

8. 3. Data Link Troubleshooting • If your network runs slower than it used to run (or slower than it ought to run), the problem might be that the present network traffic exceeds the level at which the network can operate efficiently. Some possible causes for increased traffic are new hardware (such as a new workstation) or new software (such as a network computer game or some other network application). A generator or another mechanical device operating near the network could cause a degradation of network performance. In addition, a malfunctioning network device could act as a bottleneck. Ask yourself what has changed since the last time the network operated efficiently, and begin there with your troubleshooting efforts. Some of the techniques described in previous chapters can help you troubleshoot network performance. A performance monitoring tool, such as Windows NT’s Performance Monitor, can help you look for bottlenecks that are adversely affecting your network.   • The monitoring and record-keeping procedures also can help you troubleshoot network performance by providing you with baseline performance data that you can use to gauge later fluctuations. For instance, the increased traffic could be the result of increased usage. If usage exceeds the capacity of the network, you might want to consider expanding or redesigning your network. You also might want to divide the network into smaller segments by using a router or a bridge to reduce network traffic. A protocol analyzer can help you measure and monitor the traffic at various points on your network.

9. 4 Network Services Troubleshooting4.1 Perform network services troubleshooting • The following list details some other common problems that could affect your network: • Operating system conflicts. Operating system upgrades sometimes can cause older programs to become incompatible with the operating system itself. This problem is compounded in network environments because, during the transition to a new network operating system, some servers will run the new version for a period of time while others are still running the previous version. Microsoft recommends that you perform a test upgrade on an isolated part of the network to ensure that all hardware and software systems function properly when the upgrade is made. • Server crashes. A server disk crash can be disastrous if you aren’t adequately prepared for it. You should devise a system of regular backups and, depending on the nature of your data, explore other safeguards such as a RAID fault tolerant system. • Power fluctuations. A small fluctuation in the power supply can make the network misbehave. If the power goes off completely—even for a moment—the whole network could shut down, causing users to lose their work in progress. A disorderly shut-down also can cause problems with file servers. The best solution is to prepare for a power outage before it happens. Connect each server to an Uninterruptible Power Supply (UPS), and encourage your users to perform occasional saves as they work. • If you implement all the measures discussed so far and you still experience problems, your next step may be to consult the experts. Or, even before you start your own troubleshooting, you may want to consult the available information to learn more about the problem. The next section discusses some online and offline sources of help.

10. 4.1 Perform network services troubleshooting Disaster Recovery • One of the major issues that a network administrator must address is the possibility of system failure and associated downtime. The administrator must handle two major issues to guard against the danger of a failed server: i) Protecting data ii) Reducing downtime • This chapter discusses both issues and examines how the use of fault-tolerant disk configurations and a backup strategy can help reduce the danger of lost time and data. This information falls under the “Choose a disaster recovery plan for various situations” job skill in the test preparation guide.  

11. 4.1 Perform network services troubleshooting • Recovering from System FailureNext to data security, keeping the network up and running properly is the most crucial day-to-day task of an administrator. The loss of a hard drive, even if not disastrous, can be a major inconvenience to your network users and may cost your organization in lost time and money. Procedures for lessening or preventing downtime from single hardware failures should be implemented. Disk configurations that enable this sort of protection are called fault-tolerant configurations.  

12. 4.2 Perform authentication troubleshooting. • ResourcesThe first concept to be discussed is a resource. The two key resources detailed in this chapter are data files and printers, but in theory, a resource can be any information or device relating to the network. Without networking, a resource can be accessed only by physically sitting at the machine on which the resource is installed. This means that you either access a local file or a local printer. The creation of a networking structure grants you the capability to use a server computer to share resources with others at remote client machines.  • SharingThis brings us to the second important concept: sharing. Only by specifying that you want to grant others access to a resource—be it a directory, a CD-ROM drive, or a printer—do you make the resource available for use from remote workstations. A shared resource is simply a resource whose owner has leveraged networking to make it available for use by others.

13. 4.2 Perform authentication troubleshooting. • UsersA user is anyone who requests network resources. In most cases, you assign a unique username and password to every individual on your network. Users can be created on a number of operating systems, including Windows NT, NetWare, and Unix. Users cannot be created on Windows 95 or Windows for Workgroups because neither of these operating systems have the capability of establishing a user database. Both systems do enable the creation of in dividualized profiles, but as you see later in the chapter, they must rely on another machine’s database to provide true user authentication. • GroupsGroups are administrative units that are comprised of one or more users with similar needs of network resources. Two types of groups exist on Windows NT—Local and Global. These groups are key to efficient security in the Microsoft model.