Network Troubleshooting Tools – CompTIA A+ 220-802: 4.5

| May 27, 2013

The process of troubleshooting the network may require additional tools to solve the problem. In this video, you’ll learn about using crimpers, cable testers, loopback plugs, punch-down tools, toner probes, and wireless locators.

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When you’re troubleshooting the network, the techniques that you use are important, but so are the tools that are available to you. In this video, we’re going to look at a number of the tools that you’ll be using to help keep your network running at peak efficiency.

If you’re using a very small network, it may be easy just to buy cables that are already available to you that you could buy at exactly the length you need. But in many environments, we’re running our own cables– we’re putting cables into the ceiling. We aren’t even quite certain exactly how long the run is going to be until we finally extend it all the way through. And at that point, we need to put an ethernet connector on to the end of it. And we would use a crimper to be able to pitch that modular connector onto the end of the wire.

There are also crimpers for other technologies, like coax and fiber, as well. This one happens to be one for a twisted pair, and you can see there’s a couple of different types of connectors that you can use– maybe RJ11 an RJ45. This is usually the last step. You’ve run the wire and now you need to put the connector onto the end of the cable, and you would use this crimper to do that. The crimper is not only connecting that modular connector onto the end of the wire, it’s also pushing through these copper prongs into the wire itself to make those electrical connections. We have to be sure that we get it all the way through the installation and touching the copper that is inside of those wires if we want the signal to be able to get from one side of the connector onto the wire.

Here’s a nice close-up view of those connectors prior to being cramped. So we would put our wire into the side of it. And you can see that all of those copper connectors are still sticking out just a little bit. During the creeping process, all of those are pushed all the way through. And if you look, you can see there are some very sharp connectors on the ends of those that push into the wire when you’re pushing them in. Once you’ve crimped the connection, if you look at it, you will have the sheath and then finally the wires coming out. And now you can see that it has been pushed all the way in, and those sharp connectors are now inside of those insulated wires that are inside of that cable.

Whether you’re crimping a handful of cables or hundreds of cables, you’re going to want a good crimper. You want to be sure that you have the best quality connection that you can have at the end of that wire. If you just have a small problem, it’s going to cause you an issue. You also want to be sure that you’re using the right modular connectors for the wire that you’re using. Different wiring will require different kinds of connectors, so make sure that those match up so that you’ve got the best possible connection on the end of that wire.

This doesn’t take too long to become proficient at connecting these, but it does take a little bit of practice. So you can expect that you’re going to lose a few connections along the way, cut those off, put a new one on, and try again. But eventually you’ll get the hang of it.

One way to check your crimping and see if it worked properly is to use a cable tester. And as you can see here, the cable testers can be very basic or a little more advanced. These are designed to check your wire mappings to make sure that pin one is connecting to pin one on the other side. So you would connect these two devices, one on each side of the cable, and it will give you an idea of exactly where the signals are going. It’ll make sure that the signal is making it all the way through, and it’ll make sure that you didn’t mess up any of those wires as you were inserting them into the modular connector.

If you’re trying to troubleshoot a network and you think there might be a problem with your network hardware, you may want to use a loopback cable to help troubleshoot. A loopback cable is perfect for testing that physical hardware. It’s taking the signal that’s going out one port, turning it around, and sending it right back in to that same piece of hardware. That’s why we call it loopback. That’s exactly what it’s doing. This traffic never makes it onto the network. It’s simply being fed right back into itself. There’s different kinds of loopback connectors. You might get some for a serial connection– maybe a 9 pn or a 25 pin serial port.

One thing to keep in mind is that this is not a crossover cable. Crossover cables are used to connect two devices directly with a single cable. In this case, there’s no cable it all. It’s simply a connector that’s looping that signal back directly into the same device. You usually don’t even need loopback cables unless you’ve run into a problem. And usually, you’re loading up some type of diagnostic software or you’re configuring this network device that you’re using into a diagnostics mode that’s going to send traffic out the port and then measure how much it’s receiving and to check to make sure that what it’s receiving is exactly the information that was sent. In those cases, is you want to have this loopback connector available for all of your different network connections.

So maybe you have some fiber loopbacks that you have, maybe it’s a network ethernet copper loopback, maybe you’ve got some T1 loopbacks. Those are going to be a little bit different in the pins and the wiring. So you need to make sure you’ve got exactly the right kind for the interfaces that you’re using. And, of course, you can create your own loopback connector. They’re relatively simple to do, since you’re really just taking a wire and looping it back in. This website at can help you make a crossover cable as well as ethernet modem, null modem, and Cisco console cables. They’re very simple to make, and that’s a very good do-it-yourself project if you’re trying to come up with a way to have all of those different types of connectors available with you at all times.

If you’re working in a relatively large organization, you may have some wiring blocks that you’re using as patch panels. And in those cases, you’re going to need a punch-down tool. There’s different types of wiring blocks you’ll run into. It’s very common to see what we call a 66 block or 110 block that we’ll use for these patches. This is something that can be very tedious. You’re taking every individual wire and you’re punching it onto these wiring blocks. And you’re using your punch-down cable to go to every single wire and punch it in. And as you’re punching it in, it’s trimming the wire to exactly the right size, pushing it into the wiring block itself, and then you go to the next wire and do exactly the same thing.

And once you’re done, you have a picture that looks like this. This is a 110 block, and you can see all of the individual wires have been punched down into these wiring blocks. And you’ll notice that it has these connectors on the wiring block that we’re pushing it into that are going right into the insulation that’s around the copper and making that copper connection. So now we have an electrical connection that’s been made because we’ve pushed it down into the wiring block. Notice it’s trimmed off the wire, as well. In fact, you can see here it didn’t trim off that last piece of wire very well. But most of this has been turned off just fine, and now we have all those wires punched down into our wiring block.

If you’re going to be doing a lot of punch downs, you can see from that last picture that you’re going to need to be very organized. There are a lot of wires, and you want to be sure you have them in exactly the right spot on that punch-down block. So you want to make a lot of notes, make a lot of documentation, and make sure you know exactly where those cable drops are going. If your punch-down are being used for network communication, then you want to be sure to maintain those twists. You can’t untwist all the wires and expect it to run at its maximum efficiency. If you’re running at these higher speeds on our network, we want to be sure that we keep those twists all the way up until the point where we have to punch them down into the punch-down block.

Make sure that after you have punched these down that you have documented either on the wall itself or with documentation that you include somewhere near that punch-down information. Later on, when someone moves from one office to another, you’re going to need to go back to that punch-down block and determine what exactly changed on the network.

If somebody doesn’t document very well or you have no idea where the end of the wire might be, then you’ll want to use something like a toner probe. This is designed to find those wires, wherever they happen to go. This is two pieces. The first is a tone generator that you would connect to the wires themselves. This one happens to have these alligator clips on the end. There are also some that will plug directly in to an RJ45 or RJ11 cable. That’s going to put an analog sound on the wire.

So you’ll be able to take this inductive probe, which means that it doesn’t have to physically touch the copper, it just has to get somewhere near that signal to be able to hear it. And these have a little speaker on the end of them. And as you are moving around to all of the different wires, the sound will get louder and louder as you get closer. And finally, when you can touch the outside of that wire, you’ll hear a very, very loud, strong signal that’s coming from this tone generator on the other end of the wire.

On a wireless network, it’s a completely different set of tools. There’s no cable or punch-downs you have to worry about. Instead, you’re worried about radio frequency signals. So one of the challenges you have is being able to have your computer hear as much of that signal as possible. So you may use something like one of these spectrum analyzers. It’s able to look at a very large frequency and be able to map out what it hears on the network. These devices can also listen in and give you information about all of the different wireless machines that they have that are communicating over that 802.11 standard.

You can also pick out where your problems might be if you’re running into interference with different devices, or microwave ovens, or phones. You’ll see it listed on those wireless spectrum analyzers. Especially if you are in a building with multiple tenants, this can be really useful. You can see exactly where the access points might be and be able to adjust your network to solve any type of wireless signal problems you might run into.

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Category: CompTIA A+ 220-802

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