Your cabling is the foundation of everything
that happens with your network.
If the cabling is installed properly,
then the network is going to operate at complete and full
efficiency.
If your cabling is not installed correctly,
then nothing is going to work well.
That's why you really only get one opportunity
to install your cable infrastructure correctly.
You want to do this right from the very beginning
or you're going to run into problems
very quickly with your network.
Even your wireless networks are going to rely on these cables,
so you want to make sure your network
is installed properly from the very beginning.
Most of our ethernet networking operates
using twisted pair wiring.
This twisted pair copper cabling uses
something called balanced power operation.
That means there are two wires that interact with each other.
They're both sending the same information--
one is a positive value and one is in negative value.
So you'll see that as we're communicating
through the network, we're twisting these wires also
amongst each other.
Because these wires are twisted, there
will be a wire always moving away
from any potential interference, and when this information
gets to the other end of the wire,
those opposite signals can be compared to each other
to reconstruct anything that may have been
corrupted by this interference.
One of the interesting characteristics
of this twisted pair cable is that the different pairs
of cabling are twisted at different rates.
This becomes really obvious when you get up to a higher level
categories such as Category 6.
These different twist rates will also
help in making sure that traffic is
able to get through the network even when there's interference.
Cabling is very standardized, and these standards for cabling
come from many different organizations.
One of these organizations is the Electronic Industries
Alliance or the EIA.
This is an alliance of trade organizations
and they create standards for the entire industry.
You'll see their standards usually
start with an RS, which stands for a Recommended Standard,
or has an EIA at the beginning for the Electronic Industries
Alliance.
You can find all of their information at www.eia.org.
Another organization setting standards for our cabling
is the Telecommunications Industry Association or TIA.
In fact, the ANSI/TIA/EIA-568 standard is the Commercial
Building Telecommunications Cabling Standard,
and that is the standard that we always use whenever
we're putting in a cabling infrastructure
in our buildings.
There is also a worldwide set of cabling standards.
This is the International ISO/IEC 11801 cabling standards
that define standards across any organization wherever
they happen to be in the world.
These organizations have created standards for copper
cabling that they call cable categories.
This means that we as the end user
can simply ask for the type of cable category
that we need for a particular purpose
rather than trying to find a cable that
has a particular twist rate or a particular ohm value.
For example, in our not-so-distant past,
when we needed to run 10BASE-T ethernet standard,
we would want to run that over 100 meters,
and the type of cabling that we would need to support that
would be Category 3 cabling.
When the speeds of our networks increased
to 100 megabits and 1,000 megabits,
using the ethernet standards of 100BASE-TX or 1000BASE-T,
we could run those to 100 meters using Category 5 cabling.
There were some minor changes made to the Category 5
standard.
This change is the Category 5e standard.
The e stands for enhanced.
It still allowed us to run 100BASE-TX and 1000BASE-T
ethernet standards to 100 meters,
but it was able to do that with some minor enhancements
to the standard.
When we jumped to 10 gigabit networking
using the ethernet standard 10GBASE-T,
we were able to network 37 to 55 meters of distance
using Category 6 cables.
And we were able to improve that distance to 100 meters using
Category 6A--
the A stands for augmented.
If you were to look at a cross-section
of a commercial building, the place where everybody's working
is here in the bottom area underneath the drop ceiling.
If you were to look above the drop ceiling of your office
and you saw that there was duct work providing
air supply from the HVAC and there was separate duct
work providing the air returned to the HVAC,
then you would say that there was no plenum in this office
configuration.
This plenum is the shared area above the drop ceiling
where you would have return air, but we might also
run our network cables in that plenum-- there might even
be water pipes that run in that plenum.
This is obviously a concern from a fire perspective.
If you do have a fire that gets into the plenum
and you have network cabling there,
that network cabling could provide
fumes that might be dangerous for other people
in the building.
So your worst-case planning would
be to think about what happens during one of those situations,
and you want to be sure to have the proper network cabling
if it's going to be in a plenum.
The jacket that's on the outside of a network cable
is traditionally made of PVC.
This is polyvinyl chloride, and if polyvinyl chloride catches
on fire, then there could be fumes that
might be toxic to human beings.
So if you're running cable inside of a plenum,
you want to use a plenum-rated cable--
this is a fire-rated cable jacket that's made of either
FEP--
this is fluoridated ethylene polymer,
or something that is a low-smoke polyvinyl chloride.
This is a way that you're able to minimize
the impact if there's a fire but still
have a proper type of cabling to use in that plenum area.
This plenum-rated cable jacket that's
on the outside of these cables may not be as flexible
as your traditional PVC cable, so you
do have to think about how you're
going to run that cabling if you get into a tight area.
But the important thing to consider
is that you have the proper safety precautions in place,
and if you're engineering or building
out the cabling in your building,
make sure you're using the right kind of cabling depending
on where it's going inside of your plenum
or outside of your plenum.
If you stripped away the outer jacket of the ethernet cable
that you're using on your computer,
it would probably be UTP or Unshielded Twisted Pair.
There's no additional shielding in an untwisted pair cable,
it's simply the outer PVC jacket and the cables inside.
If you work in a manufacturing environment or an environment
where there's a lot of electrical equipment
or other equipment that might cause interference,
you might want to use STP or Shielded Twisted Pair,
and you can see the shielded twisted pair,
there is a foil shield that is around all of those wires.
Some shielded twisted pair even has
a shield around the individual pairs of wires themselves.
You'll notice the shield twisted pair also has a grounding wire,
so that's another consideration if you're
planning to install STP.
It's difficult to know whether you're
using UTP or STP if you simply look
at the outside of the cable.
But there's usually some printing
on the outside that can help you make that determination.
If you see an abbreviation of U, then it's
an unsheathed twisted pair cable; if you see S,
it's a braided shielding; and if you
see an F on the outside of the cable, it is a foil shield.
So what you should expect to see is
that there is a letter that identifies
what the shielding is for the overall cable,
and then a separate letter that identifies what the shielding
is for the individual pairs.
If your cables are like this one,
it has foil around the cable itself but no
shielding at all around the individual pairs,
it will be labeled as F/UTP.
Here, for example, is a Category 7 cable
that's labeled with S/FTP.
That S means that there is a shielded cable around all
of the wires that are inside of this cable,
and then the FTP specifies that each pair of wires
will have a foil shield around each pair.
You can see those combined together will be the S/FTP.
Now that we've chosen the right category of cable,
we've decided whether it's going in the plenum
or outside of the plenum, and we've
decided if it's going to be unshielded twisted pair
or shielded twisted pair, now we somehow
have to match each one of those individual wires
with the pins that happen to correlate
to our ethernet connection.
That standard for pins is called T568A and T568B termination
standards.
These standards come from the EIA/TIA,
and the standard that specifies the termination type
is called 568B standard.
Technically this is the eight conductor 100-ohm
balanced twisted pair cabling standard.
The connector that's on the end of your ethernet cable
is an RJ45 connector.
This is also called an eight position, eight conductor
connector.
And this EIA/TIA standard specifies two different ways
that you could punch down the pin-outs for any type
of ethernet connection.
The standard specifies that you would
run the pin-outs associated with T568A if you're
running cabling horizontally-- that
means on the same floor of a building.
But many organizations have chosen to use 568B,
and once you run one type of cabling standard
in your environment, you tend to use that same standard
everywhere.
What you don't want to do is terminate
one side of the cable with the 568A pin-out
and the other side of the cable with the 568B pin-out.
These will create problems for you--
you won't be able to run ethernet at gigabit speeds,
for example, and you may find some confusion
when you're trying to troubleshoot problems
with your cabling.
These are the two standards for 568A and 568B.
These numbering standards are associated with the pins
in your ethernet connector.
You can see the RJ45 connector here,
and they're pins number 1 through pins number 8.
We're assigning a different color to each individual pin
depending on whether it's 568A or 568B.
One thing you'll notice is that there are similarities
between these two standards.
For example, pins 4 and 5, which are blue and white and blue,
and pin 7 and 8, which are white and brown and brown,
are exactly the same whether you're
wiring with 568A or 568B.
The only pins that are different between the two
would be pins 1 and 2 and pins 3 and 6.
And you can see that they are alternating
between white and green and green
and white and orange and orange.
With 568A, you have white and green and green
in pins 1 and 2, and white and orange and orange
in pins 3 and 6.
With 568B, those colors are swapped.
So you can see pins 1 and 2 are the orange pairs,
and pins 3 and 6 are the green pairs.
Once you get some practice, you should
be able to look at an ethernet cable
and see the different colors and determine
what cabling standard was used for this particular cable.
You can see there is white and orange and orange, there's
white and green, blue, white and blue, green,
what looks like white and brown, and then a brown.
And if we were to look at our 568B standard,
we would see that those colors match these pin-outs exactly.
Another type of cable that you might
find for a wide area network cable modem and other uses
is a coaxial cable.
Coaxial means there are two or more forms that share
a common axis in this cable.
For example, we have the wire conductor that
is in the middle of the cable.
It is surrounded with a dielectric insulator,
and around that is usually a metal shielding.
All of this is then protected with a plastic jacket
along the outside.
If you're bringing in a digital cable modem connection,
it's probably coming into your facility using RG-6--
that's the coax standard for that cabling.
If you are then patching that cable connection
to other devices, you're probably
using RG-59, which is really designed for patch cables
and not designed for a long distance
communication over coax.