-Hi!
-Hi!
Here we are with our next show.
An explain video: we now 
introduce you to PoE standards.
What are exactly these PoE standards, Peti?
Well, we'll talk about the passive standard, 
we'll cover the af, at and bt standards,
-It's 802.3!
-That's right!
af, at', bt —Type 1, 2, 3, 4.
-Let's dive right in!
-Let's do it.
But Peti - what is PoE used for in the first place?
Well, PoE or in other words, Power over 
Ethernet is used to power devices.
You can use it to power for instance, IP cameras, 
Wi-Fi AP's, what's more, even laptops,
using certain PoE standards, or LED panels.
-Right. We have seen something like this at Ubiquiti...
-Indeed.
-...a LED solution like this. 
We've also seen a controller powered by PoE too,
For instance. And while we are at it, at Ubiquiti, 
in most cases, a passive PoE is used.
- Not just at Ubiquiti, 
- ...with point-to-point and with multipoint devices!
With Wi-Fi, it's been already standarized 
for some time, luckily.
Yes, but there also it can be used, 
not just standard PoE but passive too.
What is passive PoE, let's start with this.
Passive PoE is when we transfer power voltage on the blue-white, blue-brown or white-brown pairs of wires.
without further inquiry. We don't ask the client device 
we're powering whether it wants power or not.
We are providing the voltage anyway 
whether it wants it or not.
If, for example we feed it a 48V voltage, 
our laptop might not like that 48V so much,
and it will thank us with some smoke coming out of it,
and we have managed to turn our Gigabit interface 
into a 100Mbit interface in a blink of an eye.
Therefore, with passive PoE 
we should be watching closely.
Indeed. With this, what we connect to it, 
will receive that supply voltage
And this has caused a lot of problems in the past:
Now this is what all of the standards we mentioned earlier - af, at, bt - are meant to put an end to.
There is a communication here between the client device, or the powered device
and between the switch or PoE sender device
Now let's delve into this thing. How does this 
work, what is the method for this?
Well, let's start at the beginning.
Now, you mentioned several standards.
There are standards 802.3af, and also at and bt.
These go by the nickname "active PoE".
When the PSE itself, that is, the PoE switch, or the PoE device that supplies the PD, the client device,
they communicate with each other 
whether the client device needs PoE of not.
It it needs it, it will receive the specified voltage, 
it classifies them into the specified class
and it will work like that.
Let's see these.
First, how does PoE emission work?
For simplicity's sake, the PoE switch, transmits a voltage around 5 volts to the specified pairs of wires,
and checks whether the client 
device is PoE capable or not?
-If it is PoE capable...
-that is, it answers...
Yes, it answers, and, on a somewhat bigger voltage, 
say, 20V, they communicate with each other
as to what class type the client device is belongs,
This class means a performance level. 
For example, it classifies the client into a 7W class.
And this 7W the switch allocates to itself, saying, 
"I'll spare these 7 watts for this client device".
So, PoE switches, logically have a kind of PoE-budget, - which should be thought of when planning a network -
but you're saying that the switch itself knows how much is it's power budget, and keeps allocating from that?
depending on the order on how we connected 
the PoE enabled devices to it one after another.
Yes. This is necessary because, for example, 
if we take an IP camera
in daylight period it consumes some 3 watts,  
a relatively low power consumption.
but then comes the night, infrared must be turned on, this means it will consume more power.
But it communicates this with the switch in advance, what will its maximum power consumption,
so as to not run out of PoE budget, 
and none of our devices work.
These are ranked into so called classes.
But, if our client supports the LLDP function, 
we don't have to observe classes,
the client can inform the switch about its 
power consumption requirements
even in steps of 0.1 watts.
and the switch will only allocate that much of its power.
I see.
So, we discussed discovery, classification, 
and operational mode.
Operational phase is essentially when the device receives the power and starts up, we didn't mention that,
-And now...
-How many volts of power does it receive?
-Indeed, how many volts of power does it receive?
The client devices themselves, and the switches too,
are in a different power supply standard, 
that means that the switch itself
can transmit a greater voltage value 
than the client receive.
Why is that? Because the cable connection between 
the two can be of up to a 100 meters.
where there can be significant voltage drops.
So, it can happen that the switch has to transmit, let's say 56 volts, but the client only receives 44 volts,
due to the long cabling and big power consumption.
-So there is a loss of power in the cable.
-Yes. That's why cable choice is very important.
Now,I think this topic is a bit tangled
as there are several nominations in the market, every manufacturer has a name for these standards.
Some refer to them as 802.3af, at, bt
some call it PoE, PoE+, PoE++, and I think
in two years we'll see PoE+++++ coming.
And there are the Type nominations, 
PoE Type 1, Type 2, Type 3, Type 4,
Now let's put some order into these things.
Let's see.
Ok, let's start with Type 1 PoE or af.
Now all three nominations are perfect.
So, with 802.3af PoE, or in other words, this is standard Type 1, the power switch can transmit 15.4 watts
of which our client can use 12.95 watts.
This PoE standard can work in 
a number of different ways.
with a so called Mode A or Mode B supply.
Mode B supply means power supply goes through the blue-white-blue, brown-white-brown pairs of wires,
On the other, orange-white-orange, 
green-white-green goes the data.
That is "traditional" PoE supply, this is generally used.
But there is an option to use Mode A supply, too,
when we only use the , orange-white-orange, 
green-white-green pairs of wire, here goes the data,
and also our power supply goes through here.
We must be careful, not all PoE switches and PoE devices support both standards.
So when you buy some PoE device, a switch, 
you must check the compatibility of both,
not just whether its an af, at, or bt PoE we're talking
Let's move on. This was standard Type 1.
Type 2 or PoE+ or, in other words, 802.3at PoE, 
this can deliver 30 watts on the switch side,
and the client can pick up somewhat less, 
some 25.5 watt of this power.
There is the same PoE supply here, 
Mode A and B are both available,
the only difference being that 
we are have a little more power.
This is a 2009 standard, and not long ago, in 2018, standard bt was introduced.
Right away owning two types, Type 3 and Type 4,
the differences of which are to be found 
in their performances.
but there is some more trickery to it, and 
since this is the latest standard,
with the least of usage experience. 
Here we'll be sharing some interesting facts about that.
There is a little difference between the two.
One of them, Type 3, has 60 watts of power, while Type 4 can deliver up to 100 watts on the switch side.
One of the biggest differences between the two is that with Type 4 devices can only be supplied with power
that we supply power on all 4 pairs of wires.
Not just the blue-white-blue and brown-white-brown,
but deliver the voltage also the on green-white-green 
and the orange-white-orange.
and with a transformer, we detach this from data.
With Type 4, if we'd like to transmit 100 watts of power, then this is the only type of power supply we have.
While with Type 3 we have the option to reach back to older standards, we can use Mode A or Mode B as well,
If we feel like doing so.
WIth the bt standard there is another thing 
we must watch: temperature.
940 mA by pairs of wire, almost an amper, 
that can generate quite some heat
We must fight this heat, you see, we are feeding 
100 watts into these low current cables,
And it's one thing we feed this in: but, as per the standard, we transmit 100 watts,
but its only 71 watts that our client takes up...
-...We are losing 30 watts!
-...in any circumstance.
We are generating 30 watts of heating 
on 100 meters of cable.
Just imagine, when we'd like to dissipate 30 watts 
of heat in per cable a cable duct with 50 cables in it.
Now that can cause some surprises if we started out with the wrong thermal planning.
And here we get to a point where bt is not the thing 
we don't need to know too many things about.
other than plug it in here and there and it works, 
like  with the previous cases,
Here we should watch the type of cables, since while all standards just specify the use of CAT-5 cable,
here, due to the high heat loss 
it might be worth to step up to CAT-6.
- Or rather, CAT-6A. The higher the cable category, the bigger the cross section of the single pair of wires.
therefore voltage is lower, loss of performance is also lower and less heat is dissipated.
That's right. It's also proportionally expensive,
 evidently, if more copper gets into the cable
it makes it rather directly 
proportional to the price of the product,
But we need to know that if we want to transfer 
100 watts, we need a lot of copper for that per cable.
Then let's leave the advices for last.
Here come the best advices we can give 
for bt PoE power supplying,
Let's start with the tubing. 
What do we have to watch when tubing?
We have to take care to leave enough room in the specified tubes, if we want to lead many cables in it,
to observe heat dissipation.
If we take a thin tube, for example a 25 tube and put 4 FTP cables, they fit in nice, no problem,
but if we want to provide 100 watts on all four, it will generate such heat that it can cause serious problems.
In such a case, cables can go up to around 90° Celsius, which can mean a serious issue
under the ground or at the site.
So it's good to take into consideration to choose 
a high heat tolerance cable,
if we want to transfer higher power supply rates.
This you can check on the cable sheath, 
the heat tolerance they are designed and certified for.
And while we are at the sheath 
- you might want to buy grounded cables,
if it is covered in this metal shield, 
it can dissipate heat more.
and the cable can cool down.
But we must watch not just the sheath 
but the connectors of the cable, too.
Yes, we should watch the fittings as well. It's a good idea to use metal coverings at all parts of the cable,
since metal transfers heat better than plastic, 
and here, as we mentioned before,
you can easily heat away 30 watts, 
so it really does matter what we build on.
And due to this same reason , for Type 4 IEEE expressly provides that thermal design is necessary
if we want to transfer 100 watts,
while in earlier editions of the standard 
there was no such requirement.
Now we have to take thermal design into consideration.
if we are to choose bt and Type 4 
power supply for our devices.
What is becoming more and more interesting, 
and we can see a tendency now,
manufacturers of switches and access points are launching devices with increasing power requirements,
These higher power demand devices need 
more power to quench their hunger.
It is not by chance that the bt standard 
was recently brought to life
bt enabled PoE switches are round the corner,
there'll be lots of hundreds of watts of power 
to be distributed on these cables,
Plan smartly and in advance.
And be sure to use a good quality cable, 
because in the future,
I think PoE-powered smart TVs and inkjet printers 
and the like will not be uncommon things,
there will be no problem to have those.
But, if you use lower category cables, 
they might not work properly.
Thank you for your kind attention, if you haven't already,
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See you next week, until then - have a nice weekend.
-Bye!
