I went to Vegas and I spoke to Jim about

issues that you may encounter with fiber

optic cables as well as ethernet cables.

If it says that a cable is Cat 8, is it

actually Cat 8? If a cable says that

it's Cat 6, 6A, or whatever, is it

actually that type of cable? If you

touch fiber optic cables, does that

change the performance of a fiber optic

cable and cause problems with fiber

optic cables? We spoke about multiple

things. Use the timestamps below if you

want to jump to certain parts of the

video. I'm going to be creating a series

of videos talking about cables, issues

that you may encounter with cables, etc.

Please let me know the types of topics

that you want me to cover.

>> Jim, I've heard it's a really bad idea

to touch the tips of fiber optic cables.

Is that true?

>> It's not a danger to your finger, no.

But it doesn't improve the performance

of the light going through. We've got a

fun experiment. Let's take a look at

what happens if we have a dirty

connector. So, first we're going to take

a look at our connectors. Just going to

use a camera here and slide this in. You

know, as we get on in life, we learn

that it's important to put on our safety

glasses if we're trying to get something

in focus. Okay. So, this is a clean

connector. This is a multi-mode

connector and we can see the core that

is larger circle. Larger circle is about

the width of a human hair. And we can

see the cladding. There's a speck of

dirt off to the side, but this is a

clean connector. Let's remember that the

red boot is a clean connector and I'm

just going to put it in this fiber optic

coupler here. Now, let's take a look at

this other connector and this other

connector should also be clean because

we want to talk about how Yeah,

beautiful, clean. So, just a touch.

And this is in Vegas where it's really

dry. Our hands are dry, but I still have

some oil on my finger. And yeah, that's

not going to improve the performance.

But what happens is I have my clean

connector and I put my dirty connector

on it. And now we're going to go back to

what was our clean connector and we're

going to get what I like to call the

coffee cup stain because we have

>> Oh, wow.

>> transferred the dirt over. Now, the bad

thing is I'm going to plug this into my

SFP and my QSFP and I'm going to get

frame errors. So, I'll go, "Oh, this

cable's bad." And I will take this cable

out and I'll put the next cable in. And

guess what?

>> it again.

>> Then it's dirty again. Okay, so there is

our simple demonstration

why we want to make sure the connector

is clean. So, we have a dirty connector.

How do we clean this? Yeah, exactly.

Well, of course, you would need the

specialized fluid cleaning shirt.

[laughter]

Let's take a look at that.

>> So, just rub it with your shirt, right?

>> Uh actually, that did better than I

expected. Hehe, you are not supposed to

use your shirt to clean the connector.

What we recommend the guidance of the

connector manufacturers. So, what we're

going to do is just give this a click.

We'll slide that in. Now, some people

have asked me about how this click

cleaner works. You can see it's got a

little bit of string there. And as we

push down, the string comes out and

rotates. That wipes the dirt off the

end. But we always want to check after

we've cleaned it to make sure that we

didn't accidentally

accidentally touched it again. Phew! So,

just cleaning it is not quite enough. We

really want to clean it and then

look at it one more time.

Come along. Beautiful. We're ready to

go. We could analyze it, but trust that

that's in that's in good shape.

>> That's a great demo. This tiny molecule

of fiber cable can cause problems. You

may have errors in your network. It

could even potentially take down your

network.

>> Jim, what's the difference between

single mode and multi-mode fiber?

>> It's a great question. Mode is from the

Latin word for path. Okay. And single

mode fiber has a single path. Multi-mode

has multiple paths. Typically, single

mode will be yellow. Multi-mode will be

blue or erica violet or lime, the new

OM5. But don't trust the jacket and

don't trust what's written on it. If we

look at it with this video microscope,

of course, never look into a fiber

because you can't see the light coming

out and it might burn your eye. The

outer circle there is called the

cladding. It's about the width of a

human hair and in the middle we have the

core. The core of the fiber is 50

microns. That makes it a multi-mode

multiple path fiber. So now let's take a

look at the single mode connector. I'm

just going to put this back in motion.

Get back in motion. There we go. And

again with our video microscope we're

going to take a look at the single mode

fiber and uh it's a little bit dirty. We

could probably give that a clean. But

what I want to draw your attention to is

that tiny little hole in the middle. Now

one of the differences between single

mode and multi-mode is that multi-mode

is a little bit more robust. With that

larger core it can handle it can

tolerate a little bit more dirt. That

smaller core it's 9 microns

um is more susceptible to a speck of

dirt blocking it. Now the other thing

that's counterintuitive is that smaller

core allows us to send much more data

and that's based on the light source

that we transmit. Well,

this might be too much but we'll use a

VICSEL on the multi-mode and we'll use

an FP laser on the single mode. And the

FP laser we really haven't calculated

how much data we can put through it yet.

We keep adding

>> Telling you faster and faster and

faster.

>> through the same fiber. So there's a

quick difference between single mode and

multi-mode. So there's another way to

see the difference and that's with a

visual fault locator, a VFL. I'm sure

you've shown that before cuz it's always

cool to tie a knot in the fiber and see

the light coming out. I'm going to turn

on my trusty VFL here. So when I turn on

this visual fault locator that helps me

to find the end of the fiber. We'll see

the spot.

Can you see the spot that the single

mode laser makes? Now if we put a

multi-mode

cable on here

on there multi-mode cable

you'll see that the pattern is more

spread out. That's just the different

paths. If you don't happen to have a

microscope to be able to look and see

what the core size is of the fiber.

Here's a a a trick to use the VFL to

determine whether it's single mode or

multi mode. So, here we're looking at a

multi mode fiber and we can see how the

light is kind of spread out. Now, let me

switch from the multi mode back to the

single mode. And with single mode, we

should see Yeah, that the light is more

solid. Of course, as I bring it farther

away to help you guys take a look at it

there, it's going to spread out. But,

single mode does give us a more

concentrated dot there.

>> A simple way to think of this is the

following. Multi mode has a bigger core,

so it's more forgiving. Single mode has

a tiny core and can carry data much

further.

But, the downside is that a tiny piece

of dirt can block a much larger

percentage of the signal path. Now,

here's an important safety note. Never

look directly into a fiber cable to

check if there's a light. Firstly, you

can't see the light. Some wavelengths

are invisible and that makes them more

dangerous because your eye doesn't

naturally react to them. Use proper

tools, not your eyes, to look at a

cable.

>> Jim, is it dangerous to look into a

fiber optic cable to see if there's

light coming through it?

>> Absolutely. Please don't. A couple

reasons not to. Now, I'm holding both

ends of this and I can see it. So, don't

do this. Don't look into it.

You have two eyes and you don't want to

damage your one good eye. Yeah, the

light that we're transmitting, you don't

know what type of laser. Regardless

regardless of the type of laser that

you're using, we can't see that color.

We can't see that wavelength.

>> wouldn't help anyway.

>> It wouldn't help anyways. Now, if it

happens to be a high-powered laser on

the far end, you'll have a dot that will

follow you around wherever you look.

Hopefully, that will pass, but please

don't stare into fiber. Just just kind

of basic safety. One other thing that's

nice if you are going to be working with

fiber optics, wash your hands. They get

dirty really easy and if you've just had

potato chips for lunch, yeah, that's not

going to improve the performance of your

fiber.

>> Jim, how do you find the distance to

where there's a break in the fiber cable

or something like that?

>> It's a common question because I want to

find out if there's continuity in my

fiber or not.

>> Yeah.

>> So, what we're going to use today is an

optical time domain reflectometer.

>> Okay.

>> And the optical time domain reflect OTDR

sends a pulse of light out and it

measures how long it takes for the light

to come back. If something is close,

it'll come back sooner. Something is

farther away, it'll take more time. Now,

I'm just going to use this cable that's

attached. Being well prepared, I didn't

set this test up ahead of time. So,

you're going to have to watch me push

this button and say new test. And I'm

just going to say auto OTDR, just do

whatever needs to be done. And we will

say you selected and push test to start.

Now, the first thing we're going to look

at is the quality of the port here. We

want to make sure that the port on the

OTDR is clean. That's our window to the

outside world. And you can see that

we've got a big reflection there about

100 m, a little bit more than 100 m

away, about 105 m. That'd be 345 ft for

your North American audience.

>> Yeah.

>> About here. Now, to make the test more

interesting, I'm going to plug it into

this box. This box happens to have a

piece of fiber in it and we can take a

look down the fiber. Because one thing

is to know the distance to where the big

yellow fiber finder uh found the cable.

These big yellow fiber finders are

hydraulically assisted. They've got a

claw on them like this. This caterpillar

on the side

>> That's right.

>> Exactly right. Sorry. Sorry.

>> That's what always happens, right? Yeah.

>> Sure.

>> Yes, please call before you dig. So, I'm

just going to plug this cable into my

demonstration box. I'm going to push

test on the button. Now again, we'll

check and make sure that the port is

clean. We're shooting light pulse. We

see that it's a little bit longer now

and there are a couple of different

events that are happening in the fiber.

And oh, no.

>> Oh, there you go. Yeah.

>> We have failed. Now, this is the expert

view and this is what anyone's going to

look like. You don't have to understand

how the OTDR works, but I know you like

to show people how things work. So,

we're going to jump over here, and we're

going to take a look at the trace on the

OTDR, and we're going to zoom in to this

spot. Now, we're looking at two

wavelengths. That's 850 and 1300 because

we're doing multi-mode, and I'm going to

ask it to just give me one of the

wavelengths. So, what we're going to do

is measure the distance of before that

event and after that event. Put a mark

here.

I'll slide this over, and now it's

telling us that we've got about 0.9 dB

of loss. On the vertical scale, we're

measuring in decibels. It doesn't matter

what a decibel is. It's It's a

relationship between what was sent and

what was come back and what came back.

So, in the olden days, we had to look at

each one of the events to see what was

happening. Of course, it's easier today

to just look at the thing that's telling

us. We can also see the first connector.

Now, the first connector is green

because the loss is acceptable. But,

there's a quick the nickel story of how

we use an OTDR to find the end of the

fiber.

>> So, that's fantastic. So, where is the

break around What is it like around

here?

>> Well, that's not a break. That is in my

demo box, you can see here.

>> it up.

>> It says there's a bad splice. Now, we

were out on the show floor, and we were

doing a demonstration, and one of the

one of the people came by, and they

said, "Well, if the box tells you that

there's a bad splice 50 m away, what do

you need the tester for?" So, you see

here about 50 m down, we have a a defect

put in there. It's a fusion splice. We

shouldn't be able to see a fusion splice

because a good fusion splice

>> Yeah.

>> we're not going to see it. Anyways, I

was showing it to one of the people

while we were we were here, and they

said, "Well, if the box tells you that

there's a problem that far away, what do

you need the tester for?" And the worst

thing about it was they were right. But

the break in the fiber is up here at the

top. There's the distance to where the

fiber stopped. I was like 683 ft.

>> Yes.

Um, about 200 m.

>> That's right. Okay, so

we saw a break because it was the end of

the cable. You put it into that box.

There's a break about what, 150 m or

whatever it is. And that gives us the

the full length.

>> there's a defect so

>> somewhere

>> the network isn't working. You call and

you say, "Why isn't the network not

working?" And the technician comes and

if it's not something simple like dirt

on the cable. Hopefully it's dirt, we

can clean it off. If not, shine some use

our OTDR to find the distance to the

events and the distance to the end of

the cable.

>> That's right. Now, most people watching

this video probably have copper Ethernet

at home. They've probably seen RJ45

connectors like this. This is the kind

of stuff that a lot of us see every day.

Not fiber running between switches. So,

the obvious question is, does copper

behave in the same way as a fiber cable?

Can an RJ45 connector become dirty like

a fiber cable? And do you really need

Cat 8 for gaming or home networking? Jim

Bunton behind the camera had a really

good question. He's not into networking

like we are.

And his question was, "What's the

difference between say that yellow cable

and the blue cable that you got in your

hands? What you know, what what is this

Ethernet? Is that Ethernet? What's the

difference between the two of them?"

>> That's a great question. You have a

great assistant here.

>> So,

they both do Ethernet. Ethernet is the

encoding, the modulation of how we send

the signal. Yeah. Now, the media, this

is a fiber optic, a glass cable and this

is a copper cable. It has four pairs.

So, Ethernet can run on both. Now, in

your house, this

fiber optic cable probably comes into a

box at the outside of your house. Inside

your house, you probably have copper

cable. So, they both support Ethernet.

One is glass, one is copper.

>> Yes, I'm glad you mentioned that. So, So

fiber cable is glass on the inside,

whereas

the ethernet we typically have at home

is is copper, right?

>> Exactly, yeah. There are four twisted

pairs in here terminated with an RJ45

plug.

>> He was also telling us the story, and

this is definitely not me, this is

Vincent behind the cameras, how he was

messing around with cables, and he

wanted to know, based on some of the

other videos we've made,

can you make a ethernet copper cable

dirty like a fiber cable? Do you have to

clean it before you plug it in, or can

you make a copper cable dirty like a

fiber cable?

>> Copper cables are much more robust. They

handle dirt. And this is actually a

question we get because we make test

equipment, and people are plugging and

unplugging it all the time. And it turns

out, if you plug it in once, it's it has

a gold coating, and it will stay

connected forever. But if you unplug it,

it actually does better to plug it

unplug it with some frequency because if

there is a contamination, you'll wipe it

off. But no, it doesn't need to be it

shouldn't need to be inspected.

>> Jamal, I've got a piece of cable here.

I'm not quite sure what it is.

Uh

is it Cat 5? Is it Category 7? 8? How

could I test actually what it is?

>> Okay, that's a great question. Let's

take a look at how we do a

certification, a TIA-568 certification

of a cable. Now, when I read the jacket,

the jacket says Category 6.

Maybe it is Category 6. Hopefully. So,

we're just going to push test here and

run a test. Actually, I think this test

is set up for Category 5e. We'll we'll

take it easy on the cable. And what

we're measuring is the signal and the

noise. And we measure the signal and the

noise, and it tells us if this is

acceptable. And because it's saying pass

here, it has enough signal coming out,

and it reduces the noise. There are two

noise parameters. One is interference

between pairs, and the other one is

echoes that come back. And those are at

acceptable levels. So, yes, this cable

could be Category 5e.

>> Okay. Only a 5e at the moment. Yeah.

>> Yeah. So, that's interesting that it it

passed category 5e. Great.

Now, what if it said category 8 on the

jacket?

>> you but can you prove it? Yeah.

>> Can we prove if it's category 8? Let's

try running a category 8 test.

>> Brilliant.

>> Okay, so now we're set up to run a

category 8 test and we'll push test to

start. Now, this test is going to take a

little bit longer because our category

5e test measured to a frequency of 100

MHz.

>> Yeah.

>> Category 6 is 250, 6a is 500, and

category 8 is 2 GHz. So, that's a lot of

space. Takes it a little bit longer to

run the test and

>> There you go.

>> Yeah, that's not a good noise.

So, no, even if it said category 8 on

the jacket, electrically under the

jacket where the signal travels, where

it matters, this one doesn't quite meet

those requirements.

>> Jim, you just done a test on this cable,

right? And we tested it at 5e and it

passed, but I see it's failing at

category 8. Is that a problem though if

I'm at home

and I just do gaming or email, watch

Netflix, etc. Generally, do I need to

have cat 8 cable or is like cat 6 okay

for me?

>> Does the person you're playing against

have category 8? They would have that

little advantage over you.

>> good point.

>> Yep, yep, that'll keep you up. No, it's

not going to matter at all. Category 6a

will support any copper application that

you're running today and tomorrow. In

the future, something will go faster.

Somehow we'll do it. How we're going to

do it, I don't know, but category 8,

because of the shielding requirements,

in my mind, is a little bit overkill for

my residential applications, residential

installation.

>> How fast or how quick, you know, what's

the bandwidth of a cat 6a cable that you

recommend?

>> A category 6a cable is going to give us

500 MHz to work with. Now, today we have

10 gigabits, but tomorrow, artificial

intelligence is going to help us figure

out how to go faster within those 500

MHz. And this is an important thing. If

If think about the standard as defining,

for example, a road, here's how wide the

lanes are, here's what the lowest

overpass is. That helps them design what

size a different truck could be. Maybe

it will make a taller truck, maybe it

will make two trucks. Well, the

standards define the lowest overpass for

the category 6A cables, so then people

like Cisco know

how to design the truck, the vehicle

that will go on it. And I know they're

thinking about making a faster vehicle

or something else that they could put on

the cable. Some type of power perhaps.

>> But today, max speed 10 gigabits per

second.

>> This commercially available network

interface cards aren't going to be

faster than 10 gigabits, no.

>> So, the practical takeaway is this. With

fiber, don't guess. Inspect it, clean it

properly, inspect it again, and never

look directly into the cable. If the

fault is deeper in the cable, use an

OTDR to find the distance to the

problem. And for home Ethernet, don't

buy Cat 8 just because the number is

bigger. Don't believe the marketing hype

that 8 is better than 7 is better than

6A, etc. You probably don't need that.

6A for most of us is good enough. The

problem with 7 and the problem with 8 is

we don't have Ethernet connectors to

connect a Cat 8 cable to to give us 40

gig Ethernet. So, it's kind of pointless

buying category 8 cables today. For most

of us, Cat 6A or Cat 6 is good enough

and is more than what we need. If you

really want high-speed Ethernet, so

let's say you want 25 gig or you want

100 gig, then you're going to need to

look at buying fiber cables.

We once again don't have connectors that

can run at 40 gig or 100 gig on copper

Ethernet cabling. You need fiber for

that, so have a look at buying

fiber if you need really high-speed

internet, high-speed networking at home.