In this lesson,
we're going to discuss Power over Ethernet issues.
Power over Ethernet is a technology
that allows network cables to carry both electrical power
and data over a single line.
Power over Ethernet is really useful
for devices like IP cameras, VoIP phones,
and Wi-Fi access points
because it enables them to receive power
and data through the same copper network cable.
By using a single cable for both data and power,
we can simplify our cabling
and reduce the need for additional power sources
for our endpoint devices.
Now, Power over Ethernet comes in two varieties,
known as Power over Ethernet, or PoE,
and Power over Ethernet Plus, or PoE+.
PoE and PoE+ are actually governed
by different IEEE standards though.
Power over Ethernet, or PoE,
is defined by the IEEE 802.3af standard.
Now, this PoE standard was the first one
to be widely adopted,
and it has the ability to provide up to 15.4 watts
of DC power to each of your endpoint devices.
With PoE though, there's actually some power loss
that occurs as the power moves
from the Power over Ethernet switch
across the copper network cabling
and over to the endpoint device.
So the actual minimum guaranteed power available
to your endpoint device is only going to be 12.95 watts
of DC power instead.
Now, Power over Ethernet Plus, or PoE+,
is defined by the IEEE 802.3at standard.
This PoE+ standard was developed as an enhanced version
of the older Power over Ethernet standard.
Now, one of the biggest changes from PoE
to PoE+ was the increasing the amount
of power available for your endpoint devices
because PoE+ can now provide up to 30 watts of DC power
to each of your endpoint devices.
Similar to PoE though, there is power loss
that occurs over the network cable,
so the actual minimum guaranteed power available
at the endpoint device
is only going to be 25.5 watts of DC power.
Now, despite the advantages of using something like PoE
and PoE+, there are some issues
that arise when you implement Power over Ethernet
in your enterprise networks,
including things like errors associated
with the power budget being exceeded
and the incorrect standard being selected.
Now, first, we have the power budget exceeded error.
The power budget exceeded error occurs when the power demand
from the connected endpoint device
exceeds the power supply capacity
of the Power over Ethernet switch
or power ejection device.
Each PoE switch or injector is going to be designed
with a maximum power capacity that it can deliver.
This capacity is known as the power budget.
Now, this power budget is the sum of all
of the DC power available to all
of your endpoint devices connected to that switch,
not just the amount of power available
on a single switch port.
Now, whenever the cumulative power requirement for all
of your connected endpoint devices gets exceeded,
your network is going to start to have issues
with your PoE-supported endpoint devices.
For example, those devices may randomly begin
to restart themselves, or they may refuse to power on,
or they may behave erratically in some way.
To resolve the power budget exceeded error,
you should first check the power requirements for each
of your connected endpoint devices.
Then you need to add up the power requirements
for all of those connected devices and compare that value
with the total power budget available
for your Power over Ethernet source,
such as your PoE-enabled network switch.
Then, if the total you calculate
exceeds your available power budget, you need
to start considering removing some non-essential devices
to reduce the required power levels,
or you need to upgrade your PoE source,
like your network switch to one
that has a higher overall power budget.
Second, we have an incorrect standard error.
As discussed earlier,
Power over Ethernet comes in two varieties
that rely on the two different standards of PoE and PoE+.
If you're trying to run a PoE+ endpoint device
that's expecting to receive a maximum of 30 watts
of DC power, but you're connecting it to an older PoE switch
that only can provide 15.4 watts of DC power,
this will start to cause issues for that endpoint device
and it will fail to work properly.
Now, if you have a mismatch between the PoE device standard
that you need to use and the PoE standard
that your PoE enabled switch can provide,
this will also lead
to an incorrect standard error occurring.
To resolve an incorrect standard error,
you should first check the PoE standard
that's being supported by both the endpoint device
and the PoE-enabled switch.
Then you should ensure there is compatibility
between those two devices.
For example, I've used some endpoint devices
like VoIP phones that can be powered by either a PoE
or PoE+ enabled network device.
In this case, the VoIP phone could be configured
to use either of those two standards,
but I've also used some video-based phone
that will only support receiving power
from a PoE+ enabled network device
because those endpoint devices require the maximum
of 30 watts of DC power to be able
to power on and operate efficiently.
If you connected one of these PoE+ only client devices
to a regular PoE switch,
the device will either not function properly,
or it simply won't power up
because you're using that older PoE connection
and it's not providing enough power.
Now, if you have a mismatch
where your network switch
can't support the newer PoE+ standard,
you can either replace that switch
with a newer one that does support PoE+,
or you can use Power over Ethernet injectors
that match the PoE+ standard to provide more power
to your endpoint devices.
Now, a Power over Ethernet injector,
also known as a PoE injector, is simply a device
that adds electrical power
to a standard Ethernet data cable,
so you can provide both power
and data to a PoE-capable endpoint device.
So remember, Power over Ethernet is a technology
that allows network cables to carry both data
and electrical power at the same time.
Power over Ethernet issues can occur
when either the power budget is exceeded
or the incorrect standard is being used
between the endpoint devices
and the network devices that are providing the power.
When a Power over Ethernet issue occurs, you can expect
that your endpoint device
will either restart itself randomly,
won't work properly at all,
or it'll simply not power on when you try to boot it up.
Therefore, it's important for you
to understand the symptoms, potential causes,
and the troubleshooting methodologies that are used
to identify and resolve these Power over Ethernet issues
within your network.