PoE or
Power
Over
Ethernet is a technology where you can save money and time at the same time by using the same Ethernet cables both for Data as well as power. To convert the power over ethernet, you need to find a proper PoE, PoE+, or PoE++ switch. But wait! what do you know about these switches? What are the differences between them and how to choose the right switch as per your need?
PoE
PoE technology was defined by the
IEEE 802.3af standard back in 2003. Under this standard, the PoE allows a powered device (PD) like CCTV Cameras or VoIP phones to receive up to
12.95W PoE wattage, it utilizes 2 Pairs out of four twisted pairs in Ethernet cabling.
PoE Switch
It’s a device that works as a kind of power sourcing equipment (PSE), a PoE switch can supply power to powered devices via Ethernet cables to realize network connectivity. Generally, an
802.3af switch supports max power consumption of up to
15.4W per PoE port with a voltage range between
44V and
57V where as the Powered devices connected to this should have voltage ratings between
37V to
57V.
PoE+
PoE+ technology (
IEEE 802.3at standard) is an upgraded form of PoE technology, which was published in 2009. Some powered devices with more wattage requirement was the reason of this upgrade like wireless access points that require PoE wattage more than
12.95W to work normally. To tackle this the PoE plus technology was introduces, which can support high power consumption products.
PoE+ Switch
Similar to a PoE network switches, the PoE plus switch also supplies power over two pairs, but it adds an additional power class that is able to deliver more power up to
25.5W for a powered device with a voltage range from
42.5V to
57V. The max power delivered by each port of a PoE+ switch is
30W, along with a voltage range from
50V to
57V.
PoE++
With the increasing demand of power the IEEE 802.3 Standard launched PoE++ technology which is
IEEE 802.3bt standard. The main reason was to support the broader range of power consuming devices that consumes more power. They introduced two different types this time which can be classified as Type-3 & Type-4 respectively. By the way, here it is very important to mention that the previous two types are
Type-1 (PoE) and
Type-2 (PoE+).
In
Type-3 two or all four twisted pairs of a pure copper conductor cable can be used to transfer the power to a device up to
51W Max.
In
Type-4 the power is up to
71W at a Powered device over four twisted pairs in a pure copper Ethernet cable. By the way, Cisco’s proprietary technology UPoE (universal Power over Ethernet) works similarly to the PoE++ Type 3, which extends the IEEE PoE+ standard to double the power to a Powered device to 51 watts.
PoE++ is also called
UPoE sometimes.
Similarly, with the upgrade of PoE technologies their switches also upgraded to meet the need of the IEEE standards. PoE++ switches can deliver up to
60W on each
PoE port under the
Type-3 and up to
100W under the
Type-4.
Choosing the Right Switch
Below is the simple comparison chart, which is based on the above introduction and would definitely be helpful in understanding the specs more clearly and this table will lead you to choose the best switch for your need.
| |
PoE |
PoE+ |
PoE++ / UPoE |
| IEEE Standards |
IEEE 802.3af |
IEEE 802.3at |
IEEE 802.3bt |
| PoE Types |
Type-1
IEEE 802.3at |
Type-2
IEEE 802.3at |
Type-3
IEEE 802.3bt |
Type-4
IEEE 802.3bt |
| Power available at PD (Powered Device) |
12.95 W |
25.50 W |
51 W |
71 W |
| Maximum power delivered by PSE (Power Source Equipment) |
15.40 W |
30 W |
60 W |
100 W |
| Twisted Pairs Used |
2-Pairs |
2-Pairs |
2-Pairs ; 4 Pairs |
4-Pairs |
| Voltage range (at PD) |
37.0–57.0 V |
42.5–57.0 V |
42.5–57.0 V |
41.1–57.0 V |
| Voltage range (at PSE) |
44.0–57.0 V |
50.0–57.0 V |
50.0–57.0 V |
52.0–57.0 V |
| Maximum current Imax |
350 mA |
600 mA |
600 mA per Pair |
960 mA per Pair |
| Maximum cable resistance
per pair-set |
20 Ω
(Cat3 Cable) |
12.5 Ω
(Cat5 Cable) |
12.5 Ω |
12.5 Ω |
| Min Supported cabling |
Cat3 and better |
Cat5 and better |
Cat5 and better |
Cat5 and better |
| Examples of PD’s |
VoIP Phones
Access Points
Sensors
Static CCTV Cameras |
Video IP Phones
Alarm Systems
Pan/Tilt/Zoom Cameras |
Laptop’s
TV’s
LCD Monitors |
| Preferred Supported Conductor Type |
100% Solid Copper Conductor |
| Note : The presented figures are just valuable in theory. In fact, PoE series switches often oversubscribe the total power capacity of a switch with more ports. That is because many devices will use less than maximum power. For instance, if you have a switch with all PoE++ Type 4 ports, it does not mean you will use all of them at maximum load 24×7. Consequently, you need to calculate the power requirements for all the powered devices that you plan to connect to switch and select corresponding patch cables for your PoE design. |
