Speaker 1 (00:00)

Hello, everyone. In this video, we're going to be talking about power over Ethernet. Now, networking
devices need electrical power to function, and that's why they have a separate power cable. But
some networking devices don't have a power cable. It's not that they don't need electrical power, it's
just that they get their power and data from the same cable, which is through the Ethernet cable.
This technology is called POE, which stands for Power Over Ethernet. And this technology adds
convenience to networking devices.

Speaker 1 (01:43)
Power over Ethernet is a technology that delivers DC power to networking devices such as IP phones,
security cameras, and wireless access points over the copper wires and an Ethernet cable, which
eliminates the need for a separate power cable. So how does POE work? How does an Ethernet cable
supply a networking device with both data and power? Well, an Ethernet cable has four pairs of
twisted pair wires inside. So it has a total of eight wires. Now, in Cat 5 and previous versions of
Ethernet cable, four of those wires are used to transfer data, but the other four wires were not used.
So in a typical networking device, four wires were used for data and four wires weren't used for
anything. So in order to supply power to a device, early versions of POE used the four unused wires
to transfer power, while later versions of POE used all eight wires to transfer power. So here we have
a view of a Cat 5 Ethernet cable and its twisted pair wires that haven't been arranged yet.

Speaker 1 (02:53)
So if we go ahead and straighten out these wires and arrange them to the correct wiring standard,
the wires and pins one, two, three, and six are used for transmitting data, and the wires and pins
four, five, seven, and eight are used for transferring power. Now, in order for data and power to be
transferred through this cable, it must be connected to a power sourcing equipment or PSE device. A
PSE device supplies data and DC power to a power device or PD using an Ethernet cable. So in this
example, our PSE device is a POE switch, and our power device on the other end is a POE IP phone.
So when we plug an Ethernet cable into this switch, the switch will send data and power through the
cable to the phone. So there's no need for this IP phone to have a separate cable for power because
it's getting it through the Ethernet cable. Now, what if we plug this Ethernet cable into a standard
non-PO switch? Well, nothing would happen because this IP phone needs both data and power to
function. This standard switch can only transmit data through the cable and not power.

Speaker 1 (04:11)
However, there is a way to transmit both data and power to this IP phone without replacing the
switch, and that is by using a POE injector. A POE injector converts a non-POE device to a POE device
without replacing your existing equipment. A POE injector has two ports, a land port and a POE port.
The land port would be connected to one of the switch's ports with an Ethernet cable, and the POE
port would be connected into the IP phone using another Ethernet cable and then the injector would
be plugged into an electrical outlet. Now, the injector is getting data from the switch and power from
the electrical outlet, and it's transmitting them both over this Ethernet cable to the IP phone. What
are the benefits of power over Ethernet? Well, for starters, convenience, because, for example, when
you have multiple devices, such as IP phones all over a building, those phones need network data
and they also need power to function. Not only do you have to run network cables through the
building and connect them to the phones, but you also need to run power cables from an electrical
outlet to those phones. That leads us to another benefit is that it saves time and money.

Speaker 1 (05:30)
Because without POE, you may need to hire an electrician to install more power outlets in a building,
which can be time-consuming and very expensive. Another benefit is flexibility because without the
need of devices having to be near electrical outlets means that they can be placed in more ideal
locations and they can easily be repositioned later on. There are also two different kinds of power
over Ethernet. There is active and passive. When a powered device connects to a POE switch, power
is sent from the switch to that device. But some devices may require different amounts of power
than others. So if a device doesn't have enough power, it won't turn on. Or if it gets too much power,
the device could blow up. So this is why Active POE was created. When a power device connects to
an active POE switch, the switch will first test the connection to ensure power compatibility, and then
it will communicate with that device to be sure it delivers the correct amount of power that the
device needs. Now, passive POE is the dumb version of POE. It doesn't talk to the devices. It
constantly sends power and it sends the same amount of power to whatever device it's connected
to.

Speaker 1 (06:52)
This is why it's important to check the voltage requirements of a power device before connecting it
to a passive POE switch, because if you connect it to the wrong voltage, it could permanently
damage your equipment.

Speaker 2 (07:06)
Power over Ethernet was first developed by Cisco in the year 2000, which was a mechanism that they
created to deliver power and data to their IP phones. Similar to how basic landline phones get power
using regular telephone lines. And in 2003, the first standardized version of POE, which was the IEEE
802. 3af or better known as Type 1, was released. This standard had a power output of 15.4 watts,
which was enough to power certain devices at that time. So as technology progressed, engineers
realized the potential of this technology and created a newer standard to supply power to more
power-hungry devices. And in 2009, the IEEE 802.3AT standard or Type 2 was released, which is also
known as POE Plus. And this standard doubled the power output to 30 watts. And in 2011, that
power was doubled again to 60 watts when Cisco came out with their own proprietary standard
called Cisco Universal Power over Ethernet. And this led to the release of the IEEE 802.3BT standard
or Type III, which is also known as four pair power over Ethernet, which utilized all four pairs of wires.
And in 2018, the 3BT standard was amended and this had a power output of 90 watts, which is
enough to even power a laptop computer.