3.3. Identifying Tools Used for Wiring

Someone once said "The job is whole lot easier when you use the right tools!" This statement is certainly true in regard to wiring networks. While wiring networks is not "rocket science," it can be tedious and time consuming. Once you understand what goes into wiring a network, you will probably gain a much keener insight into why wireless networks have become so popular.

3.3.1. Critical Information

You should know the general purpose and features of each of the main tools that are used to wire and test a network. Be able to identify the proper tool for a given task.

3.3.1.1. Wire Crimpers

Typically LANs are wired with category 5, 5e, or 6 cable and RJ-45 connectors. While you can purchase these types of cables with the connectors already installed on them, they are only available in designated lengths. Network engineers often need to customize the cable installation lengths, so they have to cut their own cables from a spool of wire and then attach the RJ-45 connectors to the cable's wires. This requires that they place the wires into the RJ-45 connector with the colors in the correct order. This order varies depending on whether the network engineer intends to make a straight-through, crossover, or rollover cable. Table 3.1 shows the standard order of the colors for each type of cable and gives a brief description of the use of each type of cable.

Actually, you can you use any colors that you want, as long as you are consistent. You can use the wire crimper to strip the outer insulation from the cable to expose the wires so you can insert them into the connector. Wire crimpers, shown in Figure 3.3, resemble a pair of special pliers that have the right features to strip the wire as well as to hold the connector in place as you squeeze its teeth into position over the inserted wires. It is not necessary to strip the insulation from each individual wire, because the connector will "bite" through the insulation to make the contact. At first, the process of crimping wires is a tedious one, but with practice you can crimp like the professionals!

Figure 3.3. Wire crimpers

3.3.1.2. Media Tester

After you have created your new cable, you probably want to test it to make sure that it works properly. If you made only one cable, then you would likely just install it where you had intended to use it and make sure that it works. This is assuming that a network is already in place and that computers are available to test the connection. If this is not the case, or if you are creating many cables as part of a network implementation, then you might want to be able to test the cable without actually installing it in the network. In that case, you could use a media tester.

A media tester, shown in Figure 3.4, is a device that sends a current through each wire of a cable to determine whether each wire can carry the current from end to end within the cable. If each wire can perform as expected, then the cable will be able to carry the computer signal from end to end as well. Some media testers indicate that a cable is good or bad with a series of lights, others use sounds, and still others have LED or LCD panels that indicate the test results. These devices can be handy for network design as well as for troubleshooting a connectivity problem in a network.

Figure 3.4. A media tester

3.3.1.3. Punch-Down Tool

To increase the flexibility and fault tolerance of a network, most organizations do not use a continuous cable from end to end for each computer connection. Instead, each cable is connected through a series of patch panels. These patch panels provide a method of quickly changing a cable that is part of a computer's connection to the network. Typically, the front side of patch panel has several RJ-45 connector ports, but the back of the panel does not have ports and instead is "hard wired" with the wires from the cables "punched down" into special connectors that hold them securely in place. This is where the punch-down tool comes into play.

The process of punching down a wire properly takes a considerable amount of force. You could try to do it without the special tool, but you would probably break the wire or not be able to make the proper connection at all. The punch-down tool, shown in Figure 3.5, assists you in applying the right amount of pressure in the right direction. As you push in with the tool, you load up a spring, which then releases the proper amount of force to press the wire firmly into the connector while stripping the insulation off the side of the wire to ensure a firm connection with the metal connector. With a little practice, you will be able to "punch down" wires with ease.

Figure 3.5. A punch-down tool

3.3.1.4. Tone Generator

To test the connectivity of wires that run through walls and other obstructions, it is sometimes necessary to use a tool to produce a signal (or tone) on one end and then determine whether that signal can still be heard on the other end. The device that produces the signal is called the tone generator. There is also another device (which is seldom mentioned by its own name) called the tone locator. You can use the tone locator to find the signal in the wire on the other end from the tone generator and thus prove the connectivity of the wire through the obstruction.

The tone generator and the tone locator, shown in Figure 3.6, are sometimes referred to as the "fox and hound." It is not usually necessary to strip any insulation from the wires in order to locate the tone. The tone locator can usually find the tone through the insulation if you place the tone locator close to the wire. The only real disadvantage of a tone generator is that it generally takes two people to use one effectively to test several wires in a cable. Much more sophisticated devices are available, such as time domain reflectors (TDRs), which can be used by one person to determine connectivity and even determine where a break has occurred in a wire.

Figure 3.6. A tone generator and tone locator

3.3.2. Exam Essentials

Know how and when to use wire crimpers. Wire crimpers are plier-like tools used to strip the outer insulation from a cable and to compress the RJ-45 connector onto the wires inserted into it. The connector will bite through the insulation of each of the individual wires, creating a solid connection as long as the tool is used properly. Wire crimpers can be used to create straight-through, crossover, and rollover cables depending on the order in which the wires are inserted into the connectors at each end of the cable.

Explain the purpose of media testers. Media testers are specialized devices used to test the continuity of wires within a cable. Most media testers send a current through the wires to determine whether there is continuity through the wire. Media testers come in many versions; some have lights, sounds, or other types of output.

Know the purpose of a punch-down tool. A punch-down tool is used to secure wires to a patch panel. A punch down tool is a very specialized tool that applies just the right amount of force in the right direction to secure the wire. The punch-down tool and connector also cause a portion of the wire's insulation to be stripped off so there is no need to strip the insulation in each wire.

List the characteristics of a tone generator. A tone generator is a device that sends a signal through a wire so that you can verify the continuity of the wire, even if it goes through a wall or other obstruction. The signal that the tone generator produces can be sensed through the insulation of the wire by the tone locator. The tone generator and tone locator pair are sometimes referred to as the "fox and hound."