- [Presenter] The Ethernet standard
defines many cabling types,
with speeds from 10 megabits to 400 gigabits.
The most utilized cabling type
is Unshielded Twisted Pair, or UTP.
UTP utilizes four pairs of copper wire,
with each pair utilizing a different number
of twists per inch,
hence the name twisted pair.
Copper cabling comes in several categories,
each rated to carry traffic at different speeds
at differing lengths.
The next most common cabling type for Ethernet
will be fiber-optic cabling.
In essence, light is send down a glass strand
generally with a capability for higher speed
and over longer distances than copper.
Examine this diagram.
While is isn't an exhaustive list,
it does display some of the common connection types
a network admin is likely to encounter.
Notice how the I triple E standards end
in either a T or an L.
The T represents a copper connection,
while the L is indicative of a fiber connection.
Modern copper Ethernet connections
utilize RJ45 connections.
This is an interface that resembles an RJ11
which is used for telephone connections,
but is larger and designed to hold eight wires.
The order of the wires in the cable
is essential to the connection working
and working reliably.
Copper cables come in two orientations.
Either straight through or crossover.
Straight through cables were originally designed
to connect host to switch, or switch to router.
If the connection is examined carefully
on a straight through cable,
one can see that it is pinned the same on both sides.
If an engineer was trying to connect two switches,
they would need to use a crossover cable
which has different pinning on either connector.
Modern switches now use Auto Medium Dependent
Interface Crossover, or MDI-X interfaces
which means the interface will detect
if a crossover cable is required
and if so, adjust the interface configuration accordingly.
This means that in modern networks,
there really is no need for physical crossover cables.
More and more equipment these days
have the ability to be powered directly over copper
Ethernet connections.
This concept is generally known as power over Ethernet,
or POE.
Common devices are wireless APs, voiceover IP phones,
and even sensors.
There are several standards for POE,
each with increasingly higher wattages
capable of being delivered.
Fiber optic cables come in one of two types:
multimode or single mode.
Multimode is designed for transmission
over shorter distances,
while single mode is optimized for longer transmission.
Traditionally, multimode is far less expensive,
though single mode pricing has come much closer
to (mumbles).
The cable type used, single mode or multimode,
must also match the optic type that's purchased.
Optics are generally hot pluggable devices
that can be swapped to match the usage required.
Or easily replaced after failure.
The term hot swappable refers to the fact
that they can be changed out while the device is powered on.
Once cable type is determined
and optics have been purchased,
an engineer will need to ensure
that the cable ordered has the correct connector
to match both the fiber patching infrastructure,
as well as the connector type
required by the optics.
Virtually all modern optics
will use either LC or SC connectors,
and even then, most optics utilize
the smaller LC connector.
The physical layer is where
about 50% of network issues seem to occur,
so understanding cabling and the respective connectors
is invaluable to every network engineer.