Network Solution
Network allows transfer of data from one computer to another. The data transmitted flows through various physical devices and finally reaches the intended destination. The data will not be transmitted if any device on the transmission path is not working properly. Various troubleshooting tools can be used to identify the problem. The user can also locate the source that caused the problem and many a times also troubleshoot a problem.
Physical Checking by various tools
Network may stop functioning due to various reasons such as damaged cables, faulty NICs and wrong IP configuration settings. You can use the different tools available to diagonise and troubleshoot the problem. Different tools are used to measure the different network parameters. There are various third party tools available for checking the network. These tools can either be software or hardware tools.
Software tools
You can resolve various network connectivity problems using software tools. These software tools analyze the network and trace any any problems present in the network. Software tools make the task of troubleshooting networks easier. Mostly the software tools are available with the operating system such as Windows Network Monitor and HyperTerminal. You just need to configure them according to your requirement.
Loopback test
Loopback test is a testing technique in which a signal is transmitted and echoed back to the sending device after the signal has traversed all or portion of a network or circuit. The echoed signal that is obtained is compared with the signal that was transmitted. This used to evaluate the integrity of the equipment or transmission path. A loopback plug is required to perform a loopback test. Loopback plug is inserted into a port. A loopback test canbe usedto verify that RS-232 communications hardware is working. It can also test a radio interface and computers serial port.
DCE devices have a loopback capability which can be used for the testing. DCE devices are modems, multiplexers, routers, hubs, swiches, and access server. When this option is enabled on the DCE device, signals instead of being sent to the receiver, are reflected back to the sender. Loopback testing is often performed with a specialized DTE called a Bit Error Rate Tester (BERT). The basic functioning of loopback test is to send data from a port, through a jumper, and return back to the serial port. If serial port is working properly, whether you type on the keyboard will appear on the terminal window. Thus, you can test whether the port is working properly.
HyperTerminal is a program that allows you to connect to the compuers, Telnet sites, online sites and host computers using the modem or an Ethernet connection. It can be used for configuring and testing the model or connection with other sites. The message passed to and from the computer are recorded by HyperTerminal. Therefore, it can be used as troubleshooting tool.
Network monitors
Network administrators use Network Monitor to view and detect problems on local area networks (LANs). Network monitors give information related to traffic that is flowing back and forth from the network adapter. The information obtained can be used for analyzing the traffic pattern and thus help in preventing, diagonising or resolving various network problems that may occur. Network monitor also allows gathering of data that is relevent. For example, you can set filters in network monitor to capture only a specefic type of information.
Hardware tools
The problem in a network is not always due to incorrect settings in the system. Sometimes, the problem may be physical such as break in the cable, the cable connection is improper or there is a fault in network devices. You need to perform various types of test on cables and devices used for communication to identify the source of problem. You can use various hardware tools to troubleshoot a problem as mentioned below:
LAN Tester
LAN Testers are used to verify 10, 100 and 1000 Base-T Networks. It also allows you to test and repair the network. LAN Tester consists of two units, the Main unit and the Remote probe. Main unit performs the task of identifying the LAN device type i.e. whether it is a hub, switch or a PC. It also determines the speed of the LAN and type of communication link. Remote probe helps in locating cable locations where a fault is present.
Basic functions of LAN Tester are:
Ø Checking the PC to hub speed and data transmission
Ø Verifying hub to hub data transmission
Ø Checking if straight through or crossover patch cable is required
Ø Identifying the speed bottlenecks on 10 and 100 Base_T LANs.
Ø Monitor connections between two computers in a LAN
Cable Tester
Cable Tester is used to verify the electrical connections. Cable Tester consists of a source of electrical current, a volt meter, a switching matrix which connects the current source and the volt meter to all the contact points in a cable. In addition it may also consist of a microcontroller which automates the testing process and displays the result.
The connection can be tested using any of the following methods:
Ø Continuity Test
Ø Resistance test
Ø Low Voltage Test
Ø High Voltage Test
Time –domain reflectometer
A time-domain reflectometer is used to characterize and locate faults in metallic cables such as twisted pairs and cooxial cables. Optical Time Domain Reflectometer (OTDR) is an optoelectronic instrument used to study the characterstics of an optical fiber. A fast rise time pulse is transmitted along the conductor by a TDR. If resistance of the conductor is uniform and it is properly terminated, the entire transmitted pulse will be absorbed and no signal will be reflected back to the TDR. But if resistance discontinuity exists then an echo will be generated and reflected back to the reflectometer.
Protocol Analyzers
Protocol Analyzer is a computer software or hardware device. It has the ability to intercept and store entries of all the traffic that is flowing through the network on the disk. The protocol analyzer is also known an sniffer. The sniffer captures each packet that is travelling through the network and decodes and analyzes its content. You can sniff all or parts of the traffic depending on the network structure.
Two kinds of protocol analyzers are:
Ø Packet analyzer
Ø Statistical analyzer
Protocol analyzers help in identifying the most active computers on network. They can also isolate a system which is producing faulty packets or broadcast packets and thus resolve the problem. They also indicate when your network conditions are not normal. To test the devices on the network and cables, protocol analyzers generate frames and transmit frames on the network.
Volt-ohm meters (VOMs)
Volt-ohm meters is a cable testing tool which is used to measure parameters such as AC and DC voltage, current, resistance, capacitance and the cabe continuity. It can also be used to check physical connectivity. Voly-ohm meter is used to troubleshoot controllers, transformers, solenoids and field wiring.
Tone generators and probe
Tone generator is a network troubleshooting tool. It consists of a single or multi-tone signal,two test leads and a 4-conductor modular cable. The probe can easily trace the signal emitted by the Tone Generator. A tone genrator acts like a radio transmitter.
Key features of Tone Generator and probe are:
Ø Tone generator is used to locate and identify open cable pairs, individual conductors and telephone wires.
Ø To identify and trace wires or cables within a group a probe can be used
Ø Test polarity, continuity and voltage
Ø Choose either solid tone or a dual altering tone operation
Ø Volume control for noisy enviornments
Ø Work at distances up to 1524 m.
To trace a cable:
Connect the tone generator to one end of the cable
Place the tone probe to the other end of the different cables to determine the right cable.
Optical Tester
Fibre optic NICs mostly do not have any lights. So diagnosing the problem becomes little difficult. The fibre optic cables are very delicate and the connectors that connect to the NIC are the region that need not be handled carefully. So whether a problem arises the first part to check is the connectors. An optical tester is used to inspect the quality of the connections.
