Every network administrator needs a good toolkit. In this video, you’ll learn about some of the most common hardware tools to have handy.
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If you’re going to be working on networks, then you’re going to need a good set of crimpers. This will allow you to fasten the RJ45 connector to the end of the wire. Some crimpers also provide other connections so you can crimp RJ11 or coax connections on this same crimping device. This is really useful if you’re running your own cable. You can cut cable exactly to the length you need, and then put your own connectors onto the end of those cables.
The crimper is pushing these sharp metal prongs that are on the inside of the RJ45 connector into the insulation that’s around each individual wire. The crimper is also pushing a connection in on the back of the RJ45 connector that fastens it securely to the outside of the cable sheath. Here’s a good picture of these RJ45 modular connectors before they’re crimped. You can see they’re sticking out just a little bit with these copper connectors. And look at those sharp metal pieces that are on the end of the connector. That’s what’s going to push into the insulation that’s around each individual wire.
If we push our wires into the crimper and then crimp down and push those copper connections in, you should have a crimp that looks something like this. All of the cables are through the entire part of the connector, and you can see that those sharp metal pieces have now been pushed into the individual wires, all the way through these eight different connections on the RJ45 connector. You also notice on the back of the connector is a cable stay that has also been pushed into hold this entire cable in place.
Once you start doing a lot of cable crimping, you’ll know that you’ll need to get not just a very good quality crimper, but you’ll also need some electrician’s scissors. These might be called cable snaps. They’re perfectly sized to be able to work on these very small cables. You might also want a good wire stripper, especially if you work with a lot of coax. A number of crimpers will also include a wire stripper on the crimper itself.
Also make sure that you’re using the appropriate type of modular connectors for the type of cable that you have. The type of connectors that go on a category 5 are just a little bit different than those that go on a category 6 cable, so make sure you match your connectors with your cables. And although this can be a little frustrating at first, you very quickly can get the feel for pulling out all of these individual wires, putting them onto the connector, and crimping them down into the perfect sized cable.
Now that you performed this crimp, how do you know that the crimp is actually working? One way to tell is to put a cable tester on the wire. This is performing a continuity test across the wire, so you can very quickly see if pin 1 is connecting to pin 1, if pin 2 is connecting to pin 2, and so on. If something did go wrong, this cable tester can also tell you if pin 3 isn’t connecting to anything on the other side, or if any wires may have been crossed between any of the pins.
These cable testers are relatively simple devices. These usually have just about eight lights on them. This one also has a ground light. And it will tell you if the light turns on then you have continuity, and if the light doesn’t turn on, something’s gone wrong with your crimping. If you need more advanced analysis of the cable, like crosstalk information or signal loss across the wire, then you’ll probably want to bring in a TDR, or a Time Domain Reflectometer.
If you’re working with copper cables, it’s a TDR. If you’re working with fiber, then it’s an Optical Time Domain Reflectometer, or OTDR. These will be able to provide you with a lot of information about your copper cable or your fiber. For example, you can plug it into a connection, and it will estimate the entire length of the cable. Even if the cable’s going into the ceiling and you’re not able to see exactly how long it is, connecting the TDR will give you a very accurate representation of the length.
If your cable has a cut or splice, you can plug in the TDR, and it will tell you exactly how far down the cable that particular problem exists. If you’re simply trying to understand what type of cable it is, you want to understand the impedance on the cable, you can plug in the TDR and it will tell you that information as well.
We commonly use these TDRs and the OTDRs when we’re first installing a cable infrastructure, because you can plug these devices in and see just how much signal we’re losing between one side of the cable and the other. This is especially good for fiber, where you want to be sure over very long distances that you’re minimizing the amount of light loss over that run.
These TDRs often work with software that allows you to log every single connection that you’re testing, so at the end you can create a report that verifies that everything on the network is working as expected. Or if you’re concerned that there’s a cut in your fiber or copper, you can plug in a TDR and know exactly how far down that run you have the break.
The TDR is able to determine where these breaks are because it’s sending a ping of information down that wire, and it’s listening for any reflections that are coming back from any problems. The TDR will then calculate the time that it took to send that signal from the time that it heard the reflection and tell you what the distance is between those two.
The OTDR does exactly the same thing, except it’s doing it with light. It sends the light down the fiber, and then it watches for any reflection to come back. Visually, we can see this happen as we send signals down the wire. Runs into a problem, and a little bit of that signal is reflected back to the TDR. See that again. We send the signal. Some of that signal is going to make its way down the rest of the wire, but wherever we have that problem is where we’re going to see the reflection come back to the TDR.
A TDR or an OTDR can be an expensive investment. These are thousands of dollars to have a piece of equipment that’s able to perform these particular functions. And you’re probably going to need additional training so that you know how to operate the equipment and understand the results that it’s providing. But if you need some way to certify that your cables and your fibers are working as expected, this would be exactly the tool that you would use.
You can validate everything about your installation and certify that all of your network connections will be working exactly to spec. If you’re working a lot with patch panels, then you’ll probably be using a punch-down tool. This is the device that’s going to push the cable into those sharp connections on the punch-down block and be able to lock those wires in place. You would use this with a 66 block or a 110 block most commonly on today’s networks.
This can be very tedious to do, because you have to put every individual wire into each connection on the punch-down block, and then manually punch down every single one of those. While you’re punching this wire into the block, you would not only push the wire into the block, but also trim off any excess and keep that out of the way. So as long as you have all of your wires lined up, you can very quickly punch down all eight connections for a single ethernet drop.
When you’re working with patch panels and punch-down tools, you want to make sure that you’ve got everything organized. You’re going to have a lot of wires in one very small space. This patch panel helps by numbering each one of these connectors and showing you exactly where the wires go while you’re punching them down.
On today’s high speed ethernet networks, you also want to be sure to keep these twists in the wire– just as it shows here– as close as possible to where it’s going into the punch-down block. And once you’re done connecting these patch panels, you usually want to document exactly which one of these interfaces is connecting with which desk that’s out on the floor.
If you’re running your own cable and crimping RJ45 connections, it’s very common to use a cable tester to make sure there’s continuity for all eight of those pins. If you’re running fiber connections, you may want to perform similar tests on the fiber. But on fiber, we’re not checking for continuity. For fiber, we want to see just how much light is making its way from one side of the fiber to the other.
In those cases, we use a light meter that will be able to tell us exactly how much of our signal is making it through that fiber run. These light meters will send the light from one side. This may be a laser or an LED, depending on the light meter and the type of fiber that we’re using. And then we’ll have a device that’s going to measure how much of that light we’re able to receive on the other side. If you have a very long fiber run and you’re concerned that your equipment may not be able to see all of the light coming through, it’s useful to use a light meter to be able to see exactly what the results will be once you connect your production equipment.
If you’ve been working with a patch panel or with a large number of wires that’s coming into a room, and you’re trying to determine where the other end of a particular wire is, then you’ll want to use a tone generator. This tone generator will put an analog sound on the wire, and then we use a separate inductive probe to find out where the other end of the wire happens to be.
We don’t have to break the wire open or touch any copper. This inductive probe allows us to do this without changing anything with the wire. This makes it very easy to find an individual wire, even when you’re in a data center where there are hundreds of cables coming in to a single connection. You would first connect this tone generator to the wire. These usually have modular jacks and coax connections that can fit on to almost any type of cable. And then you go to the other end and start using the probe to try to find the wire that’s connected to this tone generator.
Here’s my tone generator. It’s a very inexpensive one. I don’t use it a lot, but it does come in handy. This has the tone generator here, and then it has an inductive probe that comes with it. I have connectors on the back. I can open it up. It has a lot of different options for plugging into a number of different types of network connections.
Here are some wires that are running across the floor of the studio. I plugged my tone generator into the end of the other wire. Now I’m trying to find out which one of these is connected to that tone generator. Now I can take my inductive probe. There’s a button on the front that I simply push. And now it’s listening. I simply need to only touch it to the outside of the wire. Not hearing anything on that wire, I’m not hearing anything on this wire, and you can see when I touch the middle wire, I can hear the tone that’s being created by the tone generator.
If you’re trying to perform some troubleshooting on a network connection, you may be required to loop the signal coming out of that device back into the device that it came from. This is so it can perform some tests sending some signals to see exactly what type of signals it’s receiving. The way we would this back is with a loopback plug. This allows us to test WAN connections, ethernet connections, and anything else that needs to send traffic out and loop it back to itself.
It’s common to see loopback plugs used with serial connections or WAN connections. These could be RS-232 either 9 pin or 25 pin. They might be network connections for ethernet, maybe a T1 connection. There’s even fiber loopbacks that you can use with fiber connections. It’s important to note that this is not a crossover cable. Crossover cables connect like devices to each other. The loopback plug only has one single plug on it. You can see the wires come out of the plug and then back in to loop the signal back to itself.
Multimeters are tools that any one should have in their tool bag. They of course allow you to test the AC voltage so you can see if you are getting power from a power outlet. They also have options to be able to look at DC voltage as well, so you can check the voltage that’s inside of the network devices that you’re using.
You also have continuity tests on here. And for networking, you can use those continuity tests to see if you’re getting connections between one end of a cable and another. If you don’t have a cable tester, for example, you can use this multimeter to provide that continuity check against each pin of the cable, and build your own wire map using the multimeter.
Another nice tool to have, especially for wireless networks, is a spectrum analyzer. This allows you to examine all of the different frequencies that happen to be in a particular range all at once, and you’ll be able to tell exactly where most of the signal is in that particular frequency range. For example, if you’re connecting a wireless access point for the first time, and you’re wondering if there’s anything else in the area that might be causing interference to slow down this network, you’ll be able to see that with the spectrum analyzer.
It views everything across a particular set of frequencies. So if the problem is a conflict with another wireless access point, you’ll be able to see that in the spectrum analyzer. And if there are other devices in your environment that are causing interference on those same frequencies, it will also show up with the spectrum analyzer.
Category: CompTIA Network+ N10-007