From the course: CompTIA Network+ (N10-009) Cert Prep

Troubleshooting cabling, part 3

From the course: CompTIA Network+ (N10-009) Cert Prep

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Troubleshooting cabling, part 3

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- Keeping a network humming requires meticulous care of servers, clients, and their software. But don't underestimate the critical role of a network technician's prowess in troubleshooting and fixing cabling dilemmas. It's crucial, maybe even more so than anything else. So cabling is the lifeblood of a wired ethernet network, ensuring seamless communication, interaction, and functionality. In today's video, we're diving into the nitty gritty of diagnosing and resolving wired network problems. So you'll face all of these different things on the Network+ exam. Using the wrong cable can throw a wrench in the works, whether it's just one run or an entire network. It can lead to trouble with distance, data rate, physical constraints, and let's not forget, cost implications, for any organization. When it comes to fiber optic cabling, your choices boil down to two separate ones. It's going to be either single mode or multimode fiber, choose wisely. So each type of fiber cable has its own thing going on. Single mode fiber can go the distance anywhere from 10 to 200 kilometers. On the other hand, multi-mode tops at at around 100 to 260 feet. They also differ in data transfer speeds. Single mode handles between 1 to 10 gigabits while multimode kicks it up to a whopping 100 gigabits. Within each kind of fiber cable, you've got categories with different perks. So single mode comes in OS1 for indoor use and OS2 for outdoor use. Multimode is labeled OM1 through 5. That means we've got 1, 2, 3, 4, and 5. So OM1 and OM2 are being for short distances, all right, the other ones, 3 through 5, are going to be handling longer ranges with better bandwidth. With all these options, you can't just throw any old fiber cable into your network setup. Picking the wrong one can mess with your data network's performance. Even with twisted pair copper cables, there's a right and a wrong choice. Take Cat 5e and Cat 6 cables, for example. CAT 5e maxes out at one gigabit, but Cat 6 can handle 10 gigabits. So if your network speeds are higher speeds using CAT 5e could slow things down. Always match the cable specs to what the network needs. Another thing to watch out for is whether the wires are unshielded or shielded. That can make a difference too. So in places where electromagnetic interference, otherwise known as EMI, runs rampant, shielded twisted pair cabling is your superhero. Think of computer data centers as high tech fortresses. Medical testing areas with X-ray and MRI machines as futuristic labs, and spots near high tension power lines as dynamic energy zones. Shielded cables are like knights and shining armor that fend off EMI, ensuring clear signals and zero data loss. But wait, choosing the right voltage rating for your cable is equally crucial. Imagine picking cable with too much, oomph. (chuckles) It could fry your network device or even spark a fire. So treat voltage ratings with the same respect you would given to handling a dragon's breath. Using the wrong cable type on a network isn't the only issue. Signal degradation can also be a pain. This can happen due to EMI, crosstalk, and attenuation. As copper cable gets faster at transmitting data, they become more sensitive to these signal problems. Crosstalk happens when copper strands are too close and start picking up signals from each other. Twisted pair cables have some protection because of their twists, but if you crush, bend, or move them too much, crosstalk can still mess with things, even between pairs. To troubleshoot crosstalk, you need a cable tester. This handy gadget sends a signal through the cable and checks for any crosstalk issues in the twisted pairs connected to a plug. A good cable tester will measure how reliable and how high quality your cable run is. It usually includes tools like network analysis to check impedance and transmission, TDR, to find results and faults and their causes. So the spectrum analyzer can also be used to see frequencies running through your cable. There are three main types of crosstalk that can mess with your signal. Near-end crosstalk, that's going to be called NEXT, far-end crosstalk, FEXT, and alien crosstalk, AXT. That's right, it sounds like it's from another planet. NEXT crosstalk happens when the signal on one wire messes with the signal on another wire at the same end of a cable. This could be a termination issue or damage to the cable. NEXT can lead to data errors, more noise, and less performance. It's measured as interference at the transmitting end of a cable. Next up, (chuckles) no pun intended, we've got FEXT crosstalk. FEXT crosstalk is when the signal on one wire interferes with the signal on another wire at the opposite end of the cable run. Things like EMI and signal reflections cause it, and you'll see the same issues as with NEXT. FEXT is measured at the receiving end of a cable. The third type of crosstalk is AXT, which happens between wires that aren't in the same cable or connector. AXT is caused by EMI from nearby cables, connectors, or electromagnetic devices close by. It's measured by checking for interference from nearby cables. If there's crosstalk on a cable or its connector, it means there's a problem, like an improperly attached connector, low grade cabling without enough twists in the pairs or an issue with the IDF or MDF in its inline punch downs. Next up in your journey through networking is understanding attenuation, a type of signal loss that you'll definitely encounter on your exam. Imagine a copper cable as a vibrant highway of bustling copper atoms. As an electric signal zooms through this highway, it sets these atoms into a frenzy dance, extending the signal along the path. But all that grooving generates friction, which, inch by inch, starts to wear down the signal's integrity. Eventually, the signal loses its mojo and can't be interpreted anymore. This sad moment is known as attenuation. To keep your network cables from crashing and burning out due to attenuation, you need to keep their distance in check. For instance, the golden rule for twisted pair cable is not to exceed 100 meters or 328 feet between network nodes. Fiber cabling has its own set of rules depending on the OS or OM standards. Even if you've nailed the right cable and distance, termination might still trip you up. If a cable isn't connected properly to its connector, it could spell trouble. Improper terminations can lead to connection failures, sluggish data speeds, and those pesky intermittent issues. Stick to the termination guide for each cable type and use the recommended jack or plug to avoid these headaches. And hey, even if your confidence is soaring, testing is key. Sure, plugging it in and seeing if it works feels good, but don't trust it completely. A cable tester can run diagnostics and catch low-level problems before they explode into major disasters. A common hiccup when terminating a cable is mixing up the transmit wire and the receive wire. That would be the TX and the RX. Always follow a termination guide closely for the cable and connection types to dodge this common mix up.

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