Troubleshooting Connectivity Issues

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Connectivity

There are many network/computer issues that may rise up in a shop environment. These issues may range from network slowdowns to lose of data. It is my understanding is that each location is having network issues. It is very important to have a cable company test the network cabling and switches. You also need to test for a dual ground on the electrical circuit, and any possible interference coming through the cabling. Interference can be caused by a number of sources such as cable being to close to florescent lights, electrical wiring, and more. This should be done regardless of your decision to change your current system. 9 out of 10 network problems I have run across is hardware related. The others are network configuration or Operating system issues. I have seen welders causing noise interference so badly, that data is destroyed and computers cannot see each other on the network. I have also seen network cable length of run being too far between computers and the signal degrades so much, the network does not function correctly. Once the hardware and network architecture is properly setup and functional, the base for any system will manageable.

Network Connectivity

This will cover several reasons why a network may have trouble. One such reason for poor network stability is interference. Interference can be caused by many sources, and the following describes different scenarios.

A network is a setup of multiple computer systems that are connected together using a medium of some sort. The most commonly used medium for a Local Area Network (LAN) is CAT5 cable that is made of a shielded set of four twisted pair wires for a total of eight wires. Connecting multiple computers together makes a circuit for electrical current to pass through. Data is sent from a computer as a digital signal using 3 to 5 volts. For example, 0 equals 0 volts and 1 equals 3-5 volts so a signal that would come across as 00010011 would actually be sent in potential (voltage) as 0,0,0,3,0,0,3,3. In a perfect scenario, there will be no outside voltage to disrupt the flow of this digital current.

Cabling

The cabling is the backbone of the network. Without properly working network cabling, your network will fail. Different network cabling types also have different distance ranges. The longer the cable is, the more the signal degrades and this is called attenuation. A cable run cannot exceed this distance without a repeater.

Grounding

A ground in an electrical circuit is a common return path that is the zero voltage reference level for the equipment or system, and usually is connected into the earth. Grounding is very important when dealing with electricity, because it allows the buildup of electricity to dissipate. Without a proper ground the current will become unstable and may cause breakers to activate. When properly installed, the low-resistance path provided by the safety ground wire offers sufficiently low resistance and sufficient current-carrying capacity to prevent the buildup of Hazardous high voltages. A single power outlet or light socket with an exposed or damaged wire can cause the ground to fail.

Multiple grounds

Many of the larger buildings require multiple grounds, and multi-building sites also require more than one ground. Multiple grounds are problematic do to the fact that the potential is almost never the same. If computer systems are located on separate grounds and are connected through a network, a circuit is formed out of the network wire. This creates multiple grounds on the same circuit, which will make the current from the source with negative potential flow to the ground with positive potential. This can disrupt a digital signal that would normally be 00010011 (0,0,0,3,0,0,3,3 volts) to then become 01011111 (2,4,1,6,5,4,5,6 volts). Unfortunately, a signal that is distorted in this way may disconnect a system from a network, destroy data, or even damage computer hardware.

Signal Interference

Another cause of network disruption caused by electrical interference can be attributed to equipment that produces high frequencies such as fluorescent lights, high frequency welders, generators, anything that is phase 3, etc… There is always network interference (noise) going through the network cable, but the noise to signal ratio is what is important. Some contractors and electricians do not take this into consideration when wiring a building. When installing network cable, it is important to hire a network engineer or a cabling company to get the job done right the first time.

Troubleshooting tips

One way that can help locate a problem causing network node is using a software server called telnet. Windows server does have a telnet server integrated into the operating system that is great to use. Disable the connection timeout on the telnet server that you are going to use for this test. Then connect all of your workstations to the server through the telnet client already installed on your system. Leave these workstations connected to the server for several days. Note the computers that have disconnected from the server. If only a couple telnet sessions disconnected, then you may have pinpointed the network segments (computer, network card, cable, switch) that are causing the network problems.

Example: Assuming that the server’s IP address is 192.168.1.1and the clients are running a Windows Operating System

Start->run

TYPE IN THE BOX: telnet192.168.1.1

Press OK

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