When putting a network together, or at least when
designing a network, an ideal one
would have some features there that we
wanted for our functionality.
Some would be there for security,
and some would be there for convenience.
And as we consider this typology,
we have lots of moving parts here.
We've got some layer two switches right here,
switch one and switch two.
It looks like we have a connection in between them.
It's very like a trunk.
And then we have some connections going out
to computers and printers.
Those would be access ports assigned to a specific VLAN.
And all of these devices over here
could be considered logically to be
on the inside of our network, to the left, if you will,
of this firewall providing some security
measures between the inside of the network and everything
else.
And out here on the right-hand side of the firewall,
we could consider all of this to be the outside.
And one general rule of thumb is that we don't want individuals
on the outside to have access to all the way
to the inside of our networks.
So the firewall can help enforce those rules.
But at the same time, when we have some customers that
need to get to some of our servers--
and so if we're not allowing individuals
on the outside to go to the inside, where do we put them?
And one option would be to create
a DMZ, which is an acronym for a demilitarized zone.
It's not the inside, it's not the outside,
it's somewhere in between.
And then we have some security roles,
which allow users on the internet,
for example, to access specific resources on servers
in our DMZ.
We also have routers involved.
And what routers do for a living is they forward
traffic or pack it based on the logical layer three addressing.
So while switches forward frames instead of a network at layer
two, a router is looking at layer three
and making forwarding decisions based on that layer three
information.
And this device right here is a wireless radio
that allows wireless devices like computers three to connect
to our network.
And this is referred to as an access point or an AP
for short.
And what are the challenges with putting in an access point
is that if we put it inside, for example,
a ceiling or we mount it to a ceiling, not
only do we need an ethernet connection
to connect the access point to the physical switch,
but we're also going to need some power for that access
point to drive the radios inside of that access point.
So a couple of options exist.
Number one, we can have a separate little transformer
that we plug into an outlet and plug into this access point.
But that becomes very ugly and also,
alittle troublesome to find an outlet very close to the access
point wherever you want to put it.
Another option is to include the power from the actual switch
and deliver that power over the cable that
goes over to the access point.
And that concept of delivering power
from the actual switch over the ethernet cable that
goes to the access point, so we have data and power going
over the same cable set, is referred to as POE.
That's power over ethernet.
And there is more than just one standard for it.
There's POE and there's POE plus.
And it's the IEEE that has some standards for us
regarding power over ethernet.
And that way if you have a switch
compatible with standard x, and you have an access point that's
also compatible with that standard,
you could use those two devices together
even though they're both perhaps made
from a different manufacturer, as long as they're
both following the standard.
And besides access points, there's
lots of other potential opportunities for power
over ethernet devices, including IP telephones,
or IP-based cameras, or other devices
that need power that can receive that power over the cable.
And some of the standards from the IEEE regarding
power over ethernet include 802.3 af, at, bu, and bt.
There's different applications.
Some are designed to give lots and lots of power,
while others are designed to be energy efficient.
And they can range from about 15 watts to 100 watts
depending on the type of technology
and the type of standard that's being used.
And the two primary standards that we're
going to see out there most frequently
are 802.3 af, which is commonly referred
to as power over ethernet, and 802.3 at,
which is often referred to as power over ethernet plus.
And that's a huge convenience factor
by only having to plug in one cable, a network cable,
to a device to be able to send and receive data
from that device as well as to give that device the power
that it needs to run.
In this Nugget, we've taken a look
at some design considerations and a convenience factor
in using power over ethernet to provide
power and data over the same cable set to a device.
I hope this has been informative for you,
and I'd like to thank you for viewing.