Mastering Network Cable Troubleshooting

Lots to talk about , lots to talk about , and I tell you what , when it pours , I've been having computer issues , as most of you already know , and it's been giving me lots of problems , lots of problems . That's okay , I've got to get fixed here really , really soon . So you guys might have noticed I haven't been around for a couple weeks . I was on vacation .

I took a two-week vacation , went to Tennessee , georgia , north Carolina , south Carolina , went camping all over the place , went to Falls Creek , falls , gorgeous state park , a bunch of harvest hosts , and then , when I came back , eye injury . Eye injury , yeah , holy smokes . Yeah , I was mowing the lawn and it launched a piece of mulch into my eye .

Man , I literally was nauseous , had sensitive light , just all kinds of problems going on . So I haven't been around for three weeks . So I'm back now , though . Back now . Oh hey , what are you drinking ? You know it is after hours show . So I am drinking water . Yep , water , that's it . No Zevia soda for me tonight , mostly because we drank it all on vacation .

So there you go . Somebody said they were in Gatlinburg the week of the 24th . Nice , we just miss each other then . Yeah , that eye injury was no joke , no joke . So let's move on . Let's go to the acronym challenge . The acronym challenge for today is going to be AXT , axt . What does AXT stand for ? I'll give you a hint .

It has something to do with tonight's show . Something to do with tonight's show . Yep , a-x-t . Put the answer in the chat box . If you think you know what it is , let me see if we got people answering Shotzi's in the house . Dr Pepper , as usual . Yes , there you go , mr Shotzi . Thank you for coming back again .

My friend Shotzi is one of my longest , most loyal audience members . He's been around almost since day one , almost since day one . Okay , so nobody's guessing what AXT stands for ? Nobody . It stands for Alien Crosstalk , alien Crosstalk , alien Crosstalk , alien Crosstalk is defined as how one cable interferes with another cable , usually going down the cable pathway .

But there you go . So tonight's show is going to be about testing . Actually , it's going to be a two-part series . I'm only going to get through half of it tonight . The other half will be next week's thing . So , speaking of episodes , have you caught the recent episodes , man ? I just got done putting out a bunch of great episodes .

I did one with Fiber Basics , I did one on design build , I had a guest host do the show because of computer problems and then , probably my favorite show so far to date , I had John Daniels , the CEO of Bixie , on the show and we talked about what was going on with Bixie Some really really cool stuff , really really cool stuff .

One thing I do got to get out of the way Livestreams are changing . Livestreams are changing . Live streams are changing . They will move to Wednesday nights , wednesday nights , wednesday nights , and that's going to start next week .

So if you're a regular watcher of the podcast or the live streams , I mean know that next week's not Thursday , it's going to be on Wednesday at 6 pm . So let's talk about common testing problems , right ? What do you do when your tester gives you a wire map fail ? What do you do ? What do you look at if you get a length fail ?

What do you do if you get a fail in near and crosstalk , far and crosstalk power some near and crosstalk power some far and crosstalk . What do you do if you get issues with return loss ? What do you do if you get issues with attenuation and crosstalk ratio far and or insertion loss , covering half of those tonight and the other half next week ?

But I want to start off first with wire map . What is a wire map test ? A wire map test is basically just the tester puts a signal on each of the conductors and it makes sure that that signal goes all the way through . It usually starts with pin one and then works its way through pin eight . Now , pin one is not pair one .

A lot of people get that confused . Pair one is the blue pair . Pin 1 is either the orange or the green pair , depending on which wiring scheme you're using . If you're using T568A , it's going to be the green pair . If you're using T568B , it's going to be the orange pair .

So it puts a signal on pin 1 , and the remote looks for that signal to come out on pin 1 . It's making sure that 1 goes to 1 , 2 goes to 2 , 3 goes to 3 , and you get the idea . I'm not going through all 8 . I'm not . So what are some of the common problems that you can run into with a wire map field . Let's start with the easy ones reversals .

A reversal is pretty simple . They literally just show one swap with two or four swapped with five or something like that . Generally speaking , when you get those reversals , one side wasn't terminated , right . They determinate . Instead of doing white , blue , blue , white , they did blue , white , white , blue . That's a common problem .

The easiest thing is and usually when you're testing , and this always brings up the question when you're testing , do you fix the problem while you're testing or do you do a cut sheet ? That's always the question Put in the chat box . What do you do ? Do you do a cut sheet and then come back and fix everything at once , or do you fix as you go along ?

Because there's really no right or wrong answer to that actually , I mean kind of really depends . So if you're doing the fix as you go along , the person at the patch panel just look at the connections , make sure nothing's reversed , and if it's not , then you know it's at the jack . So just pull off the jack , fix it , terminate , way to go .

Then you have transposals . Now transposals are a little different than a reversal . A transposal is where you flip entire pairs . Okay , the most common problem with a transposal one side's terminated T568A , the other side's terminated T568B . That's the most common transposal issue . So entire pairs are flipped Again . Same thing .

If you're behind the patch panel , what are you doing ? Fixing as you go along , take a peek at it . If it's not , then it's obviously at the jack . Then the next problem is an open . Now , open will show as a break in the line , right .

So when you look at the wire map , so pay attention , look and see which conductor is open right , and then start doing your troubleshooting on that . Now here are some common problems . Probably the most common issue with an open the conductor was not terminated correctly at either the jack or the patch panel . So take a quick look at that .

And here's a rule of thumb when you're terminating , as you're terminating , lay the pairs in , verify them and then punch them down . And it only takes a split second , you know , because what happens is we get stuck in working in our normal mode and that stuff like that gets missed . So with an open either it wasn't punched down all the way .

So what you got to do is you got to look at the side of the jacket and you'll notice there's like a little V groove and then that conductor , if it's not all the way down , pull it back up and re-terminate .

A lot of times if you don't have your punch tool set right or if you don't have your punch tool set at a 90-degree angle , that will cause that . Another problem that you can run into with opens is some and this is less likely , but it's happened You've got a broken wire somewhere .

The cable got pinched somewhere , it got pulled over a sharp piece of metal and it cut through the jacket . It cut a conductor . In that scenario you can use the TDR function and wire , for instance , is in the house . Use the TDR function on your tester . Look at the footage on that . Go to that footage . Look for physical damage .

Please don't splice that cable . If it's broken , replace the cable . The customer paid for a brand new cable . Give them a brand new cable . Another problem that you'll find too with opens is it has a new termination .

I've seen sometimes where somebody has put two conductors on one slot , not paying attention , so they put like the tip of one pair on top of another one . Well , you're not going to get continuity that way . So , again , a visual inspection should take care of that . Now let's talk about shorts . So a short you can have a short between two conductors .

You can have a short between all of the conductors . I did a project once where the sheetrock guys zipped up a wall and they weren't paying attention and my cable was going across the stud because there was a lot of excess there and they just kind of zipped it down and squished that cable I had .

Every conductor was shorted out with each other , every conductor , and it's just not fun . It's not fun . So with with shorts again , probably then again usually the most the most probable issue somebody didn't terminate it right . So go back and look at the jacks again , looking for double punching . You could also have where the pins are touching in the front .

I've seen before where somebody tried to insert the wrong kind of pin into like a jack and it lifted the pin and and then pin sat down in another groove and that was causing it to short out . So take a look at your jack front and back , take a look at your patch panel front and back , and that can be most likely be your problem .

You could also have bent pins . You know that happens from time to time . I did a project once where somebody was turning out a few cables and they jammed the toner so hard up into the jack that they bent the pins and they were touching . So that can also happen as well . So now let's talk about length fails .

You've tested the cable and it's failing because of length . So there's two potential items , right . So there's two potential items , right . Let's talk about what if one of the pairs seems a lot longer or a lot shorter than the others Again , damaged cable .

So what you're going to do is you're going to put on the TDR function , shoot that short one and then walk it out , look at the cable and see if it's damaged . Another issue with length fail is bad connections .

Especially if you have , like , a consolidation point and you don't have a good termination , that could give you a fail for length too , because it's not getting all the signal through that connection point . The other issue with length fails is what do you do if your length fail says your cable exceeds 295 feet , 295 feet ?

Probably the most common thing is the cable is too long . Simple , keep it simple , right . And what usually causes that is choosing a bad route . You're not choosing the shortest route to get to the drop or you're not paying attention to your slack loop . You pulled some cable , you had some slack , you just coiled it up through the ceiling .

You know you're only supposed to leave three to 10 feet of slack at the work area outlet , and in the telecom room it's supposed to go from the ceiling to the floor , to the floor , to the furthest spot plus 10 feet . So you really shouldn't have a whole bunch of slack on there .

But if you don't , if you have too much slack on there and your cables are already 270 , 285 , because you left too much slack , that absolutely could cause it to fail . So let's say that you've checked it and you don't have too much slack . Now what do you do ? You probably don't have the correct NVP set up in the tester .

Nvp stands for nominal velocity of propagation . It's defined as the speed of the electron compared to the speed of light in a vacuum , expressed as a percentage . What does that really mean ? Because those are lots of big words . When you look at a communications cable , communications cable seems to be in a range of 0.65 to 0.75 NVP .

That means the signal travels down this cable at 75% of the speed of light in a vacuum . Why is it measured in a vacuum , though , because the speed of light changes depending on what kind of medium it's going through . The speed of light going through air is different than the speed of light going through water .

The speed of light going through air in downtown Birmingham , alabama , is going to be different than the speed of light going through the air in downtown Los Angeles . You don't know why . It's because Los Angeles has a lot of smog right .

So that's why we use in a vacuum in space , because the speed of light is always 186,282 miles a second in the vacuum of space , because there's nothing to slow it down . So 0.65 means that that electron travels at 65% of that . So if you have 65% , that means that that signal is traveling at roughly 131,000 miles a second .

And the reason it pulls it up is because what happens is when you put the MVP in the tester , it sends that signal to the end of the cable . Because of a mismatch of characteristic impedance , some of the energy gets reflected back . So now the signal went all the way out , came all the way back .

It's going to take that time and divide it in half , and now it knows the length , now it knows the time and it knows the speed In order to find the distance . It's a simple mouth calculation at this point and it's so easy . I taught a class today and I use this as an example today .

If I tell you to drive a vehicle for one hour and during that entire hour you have to maintain a speed of 70 miles an hour , how far do you travel ? 70 miles thing with the mvp . So you know the time and you know the speed . So just calculate them . Says oh , this cable's 150 feet long .

So , like I said , mvp can range between 0.65 and 0.75 depending on manufacturers , different types of materials used for dielectric and other stuff like that . So you got to know there is a generic setting that they're in the testers and 99% of the time Kaelin's in the house .

90% of the time that generic setting will be fine until you start getting the cables that are close to being the maximum length If you want the most accurate . There's two ways , two things you can do Contact the manufacturer , find out what is the MVP for that model of cable that you have .

You need to know the actual model number , category , rating , plenum , cable , all that stuff , and they will tell you what the MVP for that cable is . Your NVP . And that means you can take a short piece of cable and by short I mean at least 50 feet , the longer the better and you can put two connectors on it . You can go to set NVP or determine NVP .

Depends on the tester . Plug in the testers . The tester's going to ask you how long is this cable . You tell it how long and you can figure that out by the footage markers on the cable . Do your math , double-check your math . Tell it how long that cable is . Hit the determine MVP function . It'll come back and tell you what is the MVP for that cable .

And the reason you want to do that is because when you look at manufacturing and they're putting out millions of feet of cable a year , billions of feet of cable a year yes , there are manufacturers putting out multiple billions of feet of cable a year . Yes , there are manufacturers putting out multiple billions of feet of cable a year .

Do you think there might be a difference between a batch made on one batch compared to another ? There's always going to be variances . So if you want the most accurate , do the bench test for your MVP , put in that number and then use that to test it . So if you got the MVP set correctly and it still comes back exceeding length .

You're you probably have an issue with your length . Go again , double-check everything . You're missing something somewhere . Right , missing something somewhere . You might also get a length fail if one conductor seems to be a lot shorter than another conductor . That's a possibility .

Again , with that kind of scenario , what you're going to do is you're going to shoot the cable , the TDR function in your tester , go see where it is , go check it out . So now let's talk about near-end crosstalk , far-end crosstalk , power-some near-end crosstalk , power-some far-end crosstalk .

Those are all just EMI , electromagnetic interference , just EMI electromagnetic interference . Emi is defined as how one electric electronic device interferes with another electric or electronic device . So here we're talking about cables and and and the things the environment that'll affect the cable .

With EMI there's three components an interfering source , a susceptible unit and a coupling between those two . So for near-end crosstalk , near-end crosstalk is literally how much one pair interferes another pair at the near end of the cable . Show my TikTok peeps .

So how much one pair interferes with another pair at the near end of the cable Within the first 60 feet ? Far-end crosstalk is again is how much one pair interferes with another pair . So they can see it too . One pair interferes with another pair at the far end of the cable , again within 60 feet of the end of the cable .

Powersome near end crosstalk is how much those three pair the orange , the green and the the brown interfere with that last remaining pair at the near end of the cable . Power some far crosstalk is how much those three pair interfere that last remaining pair at the far end of the gable . Okay , those , that's what that is . Again , they're all emi .

And then you also have ailing crosstalk too . Actually , ailing crosstalk is how much one cable interferes with another cable as it goes down the pathway .

So what are the most common issues ? When you get near and crosstalk failures ? Again , always go back . Don't assume it's the manufacturer , don't assume it's somebody else . It's usually you , usually you . So first thing you need to do is go back and look at your terminations . Did the jack , did they untwist one of the pairs too much ?

Remember , you're only supposed to untwist up to a half of an inch for Cat 5E and Cat 6 , and a quarter of an inch for Cat 6A . And the best way to avoid having to do those issues is , when you're terminating it , make sure the jacket comes all the way up to the back of the connector , as close as you can get it .

So that way you know you're not untwisting too much . But that can also happen at the patch panel as well . And what will happen at the patch panel ?

And this is why some manufacturers will actually tell you the best way to terminate a cable is to route the cable into the patch panel , land the two center pairs first , which would be the orange and the green , and then do the blue and the brown . That way you get an even fan .

So actually , when you go to terminate them they'll all be the same length , kind of like that . Some technicians , though they'll route in from the side . We'll take that blue pair , it'll go right up and terminate . The white-orange will be a little bit further , it'll go up and terminate , and then the green and then the brown .

Well , next thing , you know , the brown is a lot longer , a lot longer than the blue pair is . Okay , that can cause those kinds of issues , absolutely can cause those kinds of issues .

Another issue , and this is a little bit less likely If you've already looked at the connections and you've reached , best thing to do with near and crosstalk failures , foreign crosstalk failures , is re-terminate , re-test . If you're still getting that issue , then take a look at the patch cords . Sometimes the patch cords can be bad .

Always buy good quality patch cords . You can test that with a patch cord adapter , not a channel adapter , a patch cord adapter , because the problem is probably not the cable , it's probably the mod end connectors . Hey , in the chat box or in the box here below , tell me which do you prefer , pass-through or traditional ? Which kind of mod connector do you prefer ?

So you want to be able to measure that mod end connector and that's what the patch cord adapter is going to do for you . And another issue and this is actually a little more common than the last one you might have the wrong adapters being used . There's different level testers 2E , testers 3E and all that stuff .

Make sure you're using the right tester , make sure you're using the right patch cord and you should always check the patch cord adapters when you get your tester , because a lot of companies share testers . You always want to .

When you get that tester , from wherever you want to take that tester , make sure both testers are in it , make sure that both permanent link heads , both channel heads are in it , and then you want to make sure that the instruction manual is in it and the cords to charge them up . Ask me how I know that one .

Yeah , yeah , you'll make sure that that's taken care of as well . Then you really want to take a look at those heads . Look at that permanent link head . Is the tab broken off ? Is there cracks in the jacket when the permanent link adapter attaches to the tester ? There's some gold connections . Are they in good condition ? Are they dirty ? Is there stuff on it ?

Look inside the connector Is there dust inside of it ? All that can cause you problems . Ask me how I know . Yeah , it's happened to me before . Yes , so always make sure that you check those on your tester . Right . Wrong adapters ? You might also even have the wrong setting set up in your tester . You know if the previous crew had it set up for .

You know Cat 5E testing , because that's what they were doing . And now you're out there testing a Cat 6A job and you didn't think to go into the test or to change it over to Cat 6A . That could give you a near and cross-talk failure too . So double-check that setting , okay , you too . So double check that setting , okay .

And then , finally , one thing that a lot of people don't realize it can cause crosstalk issues . A kink in the cable , a kink in the cable why can this cause a crosstalk problem ? When you look at cable geometry how pairs are inside of the cable , manufacturers do them in a specific process and they lay them a specific way and then they put the jacket on .

Anytime that you do anything to this jacket , if you kink it or if it gets crushed by a staple or something , that changes the pair geometry and that brings those pairs closer together so they can start interfering with each other . So kinking a cable can absolutely cause a nearing crosstalk failure or foreign crosstalk failure .

Okay , always make sure that you watch out for that , all right . So let me see here . There was one other thing . Oh , alien crosstalk testing . So alien crosstalk testing is how much one cable interferes with another cable as it's going down the cable pathway . So what happens if you have an alien crosstalk issue ?

Realistically , the only thing you can do is go back through the bundles and separate . There was a thought in our industry 10 years ago that with Cat6A cable that you couldn't cable dress , you couldn't comb them nice and pretty , you had to put them in there randomly .

So they're all just kind of laying , you know , randomly , because they wouldn't necessarily interfere with each other , and that's because Cat6A operates to 500 megahertz . So the higher the frequency , the more interference can happen . And that was a true statement back , you know , back a decade ago .

In today's environment , manufacturers have gotten really good about pair twist , pair geometry . They're putting cross-web separators inside of them . They're changing how they lay the pairs . Instead of maybe doing them at 45-degree angles , maybe you have one pair 90 , the other pair 100 . They're doing a lot of great things . They're getting around those issues .

Alien crosstalk issue is really not going to be one that you're going to come across David's in the house , but it can still cause an issue . By the way , there's only one way to really test for alien crosstalk issues . You need to have an alien crosstalk tester . That's an additional tester on top of the tester that you have now . So keep that in mind .

So , man , a lot of times you're doing analog talk testing . You got to do what's called six around one testing where what you do is you pick what's called a victim pair and that victim pair it's got to be should be one of the longest runs and it should be in the middle of the bundle , if possible , not on the ends .

You can plug one tester into that , you can plug the other tester into the one next to it . There comes these little port plugs . You can give them to your apprentice . You can tell them run like the wind . They're going to plug in the other side and you're going to test the six cables that surround Now .

What you're really doing is you're putting noise on the victim cable to see if there's enough interference that's causing it problems . So alien crosstalk issues , Again , separation is the only way to do that . But those are going to be few and far between .

I couldn't even tell you when the last time I came across an alien crosstalk problem , not since the early days . All righty , so that covers this week . Next week we're going to talk about return loss issues . What is return loss ? How to solve that . Attenuation to crosstalk ratio far end , power-sum attenuation to crosstalk ratio far end , how to solve those issues .

And insertion loss , also known as attenuation to us old cable dogs . What is it and what could be the potential problems ? Okay , so please make sure you come and remember . Next week the live stream is on Wednesday at 6 pm . All future live streams are going to be Wednesday 6 pm until I change my mind again . So there you go . All right , oh , I forgot .

Let me go back and check the chat box . Make sure there wasn't any questions in there that I missed . Do , do , do , do , do , do . Do I like to go fix a second ? So yeah , shotzi says he likes to fix them as he goes along . Shotzi , phil Klingsmith is also the same thing as well . So , yeah , I think that's best is to .

When you're troubleshooting , make sure that you fix . Caitlin says watch it , beep coming in at 630 . Here it comes . Three , two , one . It is 630 . Time for the live stream to

end . Make sure to join us next week for the remaining part of this and until next time . Everybody , remember , knowledge is power , and if you like this show or you know somebody who could benefit from this episode , send it to them . It's going to come out on the podcast and YouTube shorts , tiktok shorts , all that stuff as well too .