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- Copper cable is the most commonly used connection media
in local area networks.
It provides high bandwidth at a low price
and is easy to install.
The vast majority of networks utilize
unshielded twisted pair or UTP.
UTP is a cable that has eight wires inside.
The wires are twisted into pairs,
leaving you with four groups of distinctly colored wires.
Since these cables are unshielded,
they rely on the twisting effect for protection.
Twisted pair cable is used to carry both voice
and network traffic.
The wires inside of the cables are twisted at varying rates
to prevent crosstalk
or the electrical interference produced by adjacent wires.
When an electrical current is sent across a wire,
it produces a magnetic field.
If another wire is caught in that magnetic field,
interference will be generated.
By twisting pairs of wires together,
the magnetic fields are canceled out.
This is not to be confused with STP
or shielded twisted pair.
STP is nearly identical to UTP,
save for the additional foil shielding
added around the pairs.
This helps to insulate the cable
from external electromagnetic radiation and RF interference.
STP requires the shielding to be grounded at both ends.
Otherwise, the shielding can act as an antenna,
possibly creating even more interference
than would have been experienced otherwise.
The additional shielding
also makes the cable more expensive.
STP is used in noisy environments
or spaces where heavy machinery
or other equipment
produces exceptional amounts of interference.
UTP and STP generally come in three flavors:
riser, plenum, or outdoor.
Riser is your everyday cable.
It is used for standard patch cables
as well as within cabinets and racks.
A plenum is the space that circulates air for heating
and air conditioning systems.
Cable rated to run in the plenum is specifically formulated
to put out fewer toxins when burned.
Outdoor cable is generally thicker jacketed
and UV protected.
It can be dry inside, gel-filled, shielded
and can contain a grounding wire.
The wire inside of the cable can also vary
in a couple of ways.
A wire made up of many small wires
that have been twisted together is called stranded wire.
This makes the cables very flexible
and more durable when bent frequently.
Stranded is usually used in patch cables.
If you have an ethernet cable in your bag,
chances are it's stranded wire.
Solid core, on the other hand,
is made from one solid copper wire.
Solid is cheaper to make and better able to carry current,
which makes it great for most fixed infrastructure.
A more legacy cable in the network world is coax.
Coaxial cable is often seen in home cable TV systems
or home satellite connections.
It is comprised of a center copper wire
surrounded by a flexible installation.
Around the installation is shielding foil
surrounded by a steel mesh and finally a jacket.
Coax cable is rated on a system called RG.
The term RG or radio guide comes from old military jargon.
The number following the RG
only loosely determines the size of the center conductor
and not much else.
Each manufacturer will produce it differently
and often you get what you pay for.
Most often, RG6 is used,
though RG58 and 59 or seen on occasion.
Coax was the benchmark connection method
for legacy networks,
but it is rarely used today.
In modern applications,
coax is used as waveguide to connect radios to antennas,
to connect cable modems
or determinate digital service three connections,
which provide speeds up to 45 megabits.
Each type of cable is used for unique purposes.
The standard a cable conforms to
is casually called Cat type,
which is simply short for category.
The various Cat ratings ensures that the cable
will have the proper number of twists for each pair
and carry a specific amount of throughput at set distances.
One of the older standards,
Cat 3 cable is a legacy standard
that was designed to carry up to 10 megabits of data,
but it's mostly used for carrying plain old telephone lines
due to its cheaper price.
Cap 5 is another legacy cable.
It was designed to carry 10 to 100 megabits
up to 100 meters or 328 feet.
Cat 5e has been the standard UTP install for years.
It runs at 100 megahertz
and can support up to gigabits speeds
at the full 100 meters.
If 10 gigabit isn't required,
this is by far the cheapest connectivity option.
A thousand foot spool of Cat 5e
can be had for less than $80.
Cat 6 has become the standard for most enterprise
and data center installs.
Not only does it have 250 megahertz rated wire,
but is capable of carrying 10 gigabits for short distances.
The cable also has better EMI rejection
due to a center divider that keeps the pairs apart.
Cat 6a is the new kid on the block
and has become the standard for many of my associates.
It contains wire that is capable of 500 megahertz
and can carry 10 gigabits for the full 100 meters.
While Cat 6 added separation of pairs,
Cat 6a kicked it up a notch
by twisting the twisted pair cables
inside into a double helix configuration.
Higher throughput comes at a cost, literally.
The higher they grade the cable,
the more expensive it is.
Another consideration is that
as the quality of the cable goes up,
so does its overall diameter,
which means you can fit fewer Cat 6a cables
in the same space that you can fit Cat 5e.
This also generally means the cables will be less flexible,
so running trunks can be more problematic.
Though there are many Cat types,
using the newest standard will allow the highest speeds.
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