Physical Testing Tools – CompTIA Network+ N10-006 – 4.2

| May 7, 2015


You can’t manage a network if you don’t have the right tools. In this video, you’ll learn about cable testers, TDR/OTDRs, multimeters, and toner probes.
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A good all around tool to have in your tool bag is a cable tester. This will tell you if pin one is connecting to pin one on the other side. It’s a relatively simple continuity test, but it can identify if you happen to have missed any pins, if any of those connections may not be connecting on one side to the other, or if you’ve crossed any of the connections. Maybe pin one is connecting to pin two and pin two is connecting to pin one. And if you’re not trying to cross those wires, you might have a problem with your patch cable.

You don’t often use these for things like testing frequencies or confirming that the CAT5 cable is going to work for your gigabit connection. If you need additional functionality for cross talk or signal loss or detailed analysis of that connection, then you’ll want to use something other than a cable tester. In those cases, you need a time domain reflectometer. Or, in the case of fiber, you need an optical time domain reflectometer. These are TDRs and OTDRs.

These are relatively costly. They’re not as inexpensive as a standard cable tester might be. And especially the fiber, the OTDRs, are really going to cost you a little bit more because they have additional electronics to handle the fiber piece of this. These are also tools that you may need additional training on. There’s a lot of details with understanding signals as they’re going across copper and light as it’s going to cross fiber, and a lot of the testing and the results you get will need to have a lot of analysis.

So you may need additional training for that. But these are very powerful tools. If you’re having a problem at Layer 1, you’re having a problem with your cable installation or your fiber installation, this is the perfect tool to check and certify that your cable plant has been installed properly. And once you run the test with your TDR or your OTDR, you can be assured that whatever you put over this particular wire is going to work properly.

Everyone should have a multimeter. It is a great all around tool not just for networking but for use in your office, in other places, and for use at home. It can check the voltage in an AC outlet and confirm that everything is wired properly and that it is giving you the right amount of voltage. It can also check DC voltage. So if you’re looking at a power supply in a computer or you just need to know if a battery has the proper amount of charge, this would be a great tool to use and it will tell you instantly what the voltages are.

And from a networking perspective, we may need to check continuity. We may need to check the pins on a serial connection or on an ethernet connection to see if we are getting signal from one side of the cable to the other. If you have a lot of cables on your network, you know that finding the right cable when you’re trying to troubleshoot can be a bit of an issue. That’s when you would use something like a toner probe. This is a device that would help you find those wires wherever they happen to be.

A toner probe is really two different devices working together. One is the tone generator, and its job is to put a signal on the wire that you’re able to hear, and it’s usually an oscillating tone. To be able to hear that tone, you need an inductive probe like the one here. The inductive probe doesn’t need to physically touch the copper of a particular cable. All it has to do is get close to it and it’ll be able to hear that oscillating tone signal coming through that particular wire.

So you can simply move the inductive probe around until you find the exact wire that that signal’s being sent through. These are very easy to use, I have a toner probe that I use in my studio especially when I’m connecting different devices through the ceiling, around a corner, through a wall, and I’m able to trace any wire I happen to have.

You never know exactly what type of connection you’ll be plugging into, so many tone generators have different types of connectors on them. They might have a modular jack or a coax connection or they might have alligator clips that allow you to connect to a punch down connector. You would then take your inductive probe, go to the other end of where you think that wire is, and just start moving it around until you hear that sound coming through that particular set of wires.

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Category: CompTIA Network+ N10-006

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