Overview of Power over Ethernet (PoE)

Power over ethernet. P O E. It's kind of amazing. Why? Let me show you. This is awesome. This phone right here. It's an IP phone to make this thing work. We need two things. We need power and we need internet and ethernet connection. We can accomplish both those things with one cable. Here we go. Here comes my favorite sound in the world. Oh yeah. And boom. With one cable power and data. So in this video, we're going to uncover unpack. Why this is so cool. I mean, obviously it is right, but we'll, we'll talk more about it and yeah, we're gonna get technical. We're even gonna get down and dirty with our Cisco switch CLI and watch some power over ethernet happen. So yeah, you're gonna learn some stuff today. And shout out to the sponsor of our video and this entire series, Boson software. If you wanna get your CCNA, CCNP, A plus security plus, whatever they are the ones you wanna look to, to get prepared, practice exams, courseware labs, they got what you need. They are what I use to prep for my certification exams. Check them out. Link below also. Let's see how smart you are. I've got a bonus question from their CCNA practice exam at the end of this video, it will be covering POE or power over ethernet. So yeah, let's do this. Now we're going to start with the how and also the why, like why are we putting power over an ethernet cable? We'll get to that. But first the whole reason we even have POE, you can thank this device right here, the IP phone. And it all started with my beloved Cisco. You see Cisco had these IP phones, right? And they're like, dang, I really hate running a power cable to this phone and an ethernet cable. What if we could just mesh those into one thing? And they did. But, you know, it wasn't called PoE. Cisco had their own name for it. In the year 2000, I was 10 years old, Cisco invented Cisco inline power. And it involves the same components you see here now. We've got our switch, and Cisco's like, man, let's beat this sucker up. Let's give it some power so we can power other stuff. In PoE terms, we call this our PSE, or power sourcing equipment, because it is the source of the power. Sorry, that was going to happen eventually in this video. And then we'll take our ethernet cable, plug it into the ports, and plug the other side into our end device, which in our case right now is a Cisco phone, and that was the case back then. I have to label my stuff because I'm a horrible artist, so that's why I'm doing that. IP phone. Again, in PoE terms, we call this our PD, or our powered device. Now, real quick, how? How are they putting power over this ethernet cable? That makes zero sense. Data, internet is going across this. How are they also powering things? Well, back in the day, they just used the... Wires that weren't being used. If you look back at our previous video in the series, we talked about ethernet cables and what each of these wires do with cat five cables and the cables before that we really only used two twisted pairs of wires on pins one and two and three and six. But then we had pins four and five and seven and eight that weren't being used at all. And Cisco was like, yeah, I got this. We're going to send power over that sucker. We're going to power our phones. And they did that. Now, at this point in time, Cisco was the only player in the game, but that won't last long. When you invent something cool, it always has to become a standard, right? Cisco knows that. So Cisco working with the I triple E, the people who make our standards brought in our first POE standard ratified in 2003 and comes 802.a F. Now this came with a few upgrades like Cisco inline power was rocking anywhere between like four and maybe five, six Watts of power enough to power a phone. For sure. Well, not this phone. This phone has a fancy screen and all kinds of stuff. It would need more power and that's why we got more power. 15.4 Watts of power. We call this our type one. POE, or we still call it type one POE. It's still around. We still use it. And now we have power for everyone. That's a beauty of standardization. It's not just Cisco devices only. Now we can use ubiquity equipment, Aruba, Juniper, and all the other off brands. We can all play now. Although what's funny, and you'll, you'll see this in a moment on Cisco devices, the commands are still Cisco inline power. It's like, they always want to remind us that they were the ones who invented it. And I can't blame them for it. It makes sense. More power to you. Now we didn't stop there. We had a quest for more power and we got there. And we'll talk about that. But before that, I want to talk about the why. Why are we putting power over Ethernet? What's the point of that? What's wrong with the regular power cable? Well, there's nothing wrong with it. We're just, we're lazy. Any good IT engineer is really lazy. That's why we automate things. That's why we have all of our technological advances. Because we're lazy. Now, what do I mean by lazy? Think about this. Whenever we deployed an IP phone, this is before PoE or Cisco inline power, or an access point, our WAP, or even our security camera. cameras. We need two things, right? We need power and we need data. We need internet. So to install all these devices in our buildings, this is gonna be my building here. Bear with me or my floor plan. This is my floor plan. We might put a WAP here, here, just a random spots in the building, right? Or not random. Like we wanna get good wireless coverage and then strategically place our security cameras and such. And it becomes a huge pain to have to run both data and power. Cuz you have to have your network engineer run data, your cable, and you have to hire an electrician to run power. That costs money and we're lazy. We don't want to do all that work. So the lazy engineers at Cisco were like, what if we could just do. Everything on one cable power and data. And that's, that's why we have it now. So now our cameras and our WAPs and our phones can be powered and given data with one cable. And we don't have to involve electricians. The network engineer can do everything. If we wanna move our WAP from over here to over here, it's just a matter of moving the cable or getting a longer one. Now back to our quest for power, because once we found out we could power phones and, uh, wireless access points and security cameras, we're like, what else can we do? So we're like, we need more power. So in comes PoE plus. We always add a plus to everything to make it seem better. It kind of works. I should come out with network chuck plus. No. The official name is 802.at. This came out in 2009 and this doubled our wattage. We're talking 30 watts per ethernet port. That's hefty, man. That's crazy. We call this type two PoE and it's awesome. We could power more devices, bigger devices. This is the most common standard by far. You'll see PoE plus everywhere. but the quest for power did not stop there. We need more power, double it, double it. That's what we did. Sorry. I'm getting a little excited around 2011. Cisco said we want more and they went off the rails again. They came out with their own version of things. They called this U P O E, which stands for Cisco universal power over ethernet. This was not a standard. This was Cisco only. And it was intense. Like we're talking 60 Watts of power. Like what are you gonna do with that? That's a lot of power over an ethernet cable. Again, this happened in 2011. And this is where things got kind of cool because Cisco started using all four twisted pairs of wires to run power. That's how they were able to do this crazy amount of power. So they were pioneers, but you know, it wasn't long before this became a standard. This goes by a few names. I've seen it POE plus plus. I've also seen four P P O E because they're using four pairs of wires, but the official name is 802.BT. And if you're following along, we call this one type. What do you think? Three. Now what are you going to do with 60 watts of power? That's a lot of power. Well, get this. We're actually using 60 watts of power to not only power phones and access points and security cameras, which by the way, I need to power up my security camera. I forgot to do that. Oh yeah. Here we go. So not just these devices, we're also using PoE from a switch from one ethernet port to power another switch, which what, what? Yes. We're using a switch to power a switch, which is really cool. Cause like, think about it. you have this one big beefy switch because these are beefy. They have like massive power supplies to be able to offer 60 Watts per port, but this switch might be, you know, in a central location and then you'll distribute your other switches, your smaller access switches. You don't have to run power to those guys. They're being powered by the switch. It's crazy, but not as crazy as this next one. No, no. The quest for power wasn't over. You didn't think it was over. Did you? No. Check this out. In comes POE plus plus plus plus plus plus plus. No, I'm just kidding. It's still called POE plus plus. I think, I don't know. It's still POE plus plus. and four PPOE and it's still called 802.BT. The only difference here is that we call it type four. Now, what is it? What's special about it? Again, it's more power. We want more power. We're talking 90 Watts now. What? Like, what are we doing with that? We're going to power the building now. This happened in 2018, I believe. And yeah, we're looking at powering some more stuff. And this is where it gets really interesting because we're not only powering phones and access points and and other switches. We're now looking at powering computers, like small computers for now, laptops over USB-C. We can power lighting, like building lighting, like LED lights. Like think about that. Your smart lighting is getting your data and power from one cable. That makes sense, doesn't it? And then even HVAC, air conditioning, powered over ethernet. I'm totally okay with the world where everything is powered over ethernet because that's just cool, right? And it's also safer. Again, you don't have to involve an electrician. Network engineers can do this. and how much power put out is actually controlled by the switch in most cases, because there are two types of POE that I want you to be aware of. And I'm not talking about type one, two, three, and four are two types of POE. We have active and we have passive. Now active is the cooler brother here. He's what we get excited about. He is what you're going to be using mainly on your Cisco switches and other brand switches, switches that run active POE will actually negotiate with the end device on how much power they're going to put out. Now, why do you think that's important? Well, if you put out too much power to this camera here, it blows up. Like it doesn't blow up, but it fries. It doesn't work anymore. You have to output the appropriate amount of power. So the switch will talk to the phone or camera or whatever it is. But how does it do that? How do they talk? How do they speak the same language? Well, a standard like everything else. Now, again, Cisco came out with their own before anyone else did. It's called CDP or Cisco Discovery Protocol. It's still used today. And basically what happens is you plug a device into a switch and they'll go, Oh, hey. who are you? Let's talk. Let's find out what you're doing here, what you need from me. It's just like shaking hands and introducing themselves. Now we do have an industry standard version of that. That's called LLDP or link layer discovery protocol. It does the same thing. And Cisco devices like switches support both. It'll default to CDP for Cisco phones and access points, but there's a device that supports LDP, which would be every other third party device. It'll switch over to LDP and they'll use these two protocols to negotiate, Hey, how much power do you actually need? I don't want to give you too much. And I also don't want to give you too little. So they talk it out and bam, they go about the day. Now passive does not do that. Passive is kind of stupid. No, it has its place. Passive is always on power. So with active, I mean, you can plug regular devices into a switch that don't need power, like your computer and stuff. And the port will automatically go, Oh, this guy doesn't need any power. I'm not going to throw power at it. He's fine with passive. That doesn't happen. Passive just says you're getting power. You're getting power. You're getting power. You're all getting power. It's like an evil Oprah. I don't know why the power's in my head. You'll often see this called 24 volt POE. It's not as popular because yeah. Um, if you plug in a device that isn't supposed to receive power, um, and that much power. It's gonna fry. Now again, I haven't seen a lot of this, but a big name brand I currently use does support this. Ubiquiti. A lot of their switches do have this, and you might be wondering, well, why would we even support that? Well, some devices need 24 volt PoE because they don't support that negotiation process. And yeah, it's probably gonna end up being a legacy equipment that doesn't support that. But anyways, let me show you what my Ubiquiti switch looks like because it does support all of these types of PoE. So here is my Ubiquiti switch. I call it the golden snitch. And here you can see I have two PoE options. I've got PoE plus and then 24 volt PoE. Now thankfully I don't have to worry too much about this. I can go into my individual ports here. Let's take port two for example. I can click on this guy, overwrite his port profile, and change it from PoE PoE plus to either off or 24 volt passive. Now by the way, it supports PoE plus which means it'll support every PoE standard before that. Every one of these is backwards compatible so that's good. So just watch out if you buy this weird switch that supports 24 volt passive and it's always on, be careful, check your stuff. Now looking at the boson core square here for the CCNA, which is amazing, by the way, you should totally check this out. They've got a great section on POE. So if you want to dive a little bit deeper than what I'm covering here, check it out. It talks about things like, Hey, there are different classes of device power, zero, one, two, three, four. And what they are going to draw from the PSE or the power sourcing equipment. And they also offer this little nugget of wisdom right here. Just some stuff that you should learn and commit to memory. If a device attempts to draw more power than a port is configured to provide what's gonna happen. A syslog message will be issued and the port will be shut down and enter the error disabled state. So things like that and memorizing the standards. So we talked about 802.AF, 802.AT, 802.BT. Commit those to memory. What they mean, what types they are, how much power they put out. And again, that's per port. But anyways, enough theory. Let's get our hands dirty. Let's get into the Cisco CLI. And by the way, I've got a lab in the description. below right now that you can play with and go along with me. So let's open that sucker up. So here we are inside Cisco packet tracer, an amazing way to practice all your Cisco skills. I mean, it really is cool. What we're going to do is actually plug up some Cisco phones to a Cisco switch and we're going to see POE happen right now. Now we're going to demonstrate this here in this application, which is fake, you know, but then I'll show you here on a real switch. So hang tight for that. But anyways, let's do our lab real quick. So first let's get into our switch. I'm going to double click our 3650 here, jump in there. and go straight to the CLI tab. We are already logged into the Switch. I am gonna type in ENABLE or enable to get into enable mode. You should have a pound sign right there next to your blinking cursor. And now what I want you to do is connect up your phones, each one, to the Switch, and then we'll check our Switch and see what happens. So we'll do that by clicking on our lightning bolt down here, Harry Potter style, which is our connections, and then go ahead and select the lightning bolt once more right here. And then we'll just start connecting. Switch to phone. Let's click it again. Switch to phone, repeat, switch to phone, push the phone. And you can see by all the blinking that things are happening. Let's go take a look at our command line real quick and check it out. I'll scroll to the top here real quick to our first few events. Our first syslog message here detected on interface one zero one power device detected I triple E PD or power device. That was like, yeah, we'll grant power. We'll allow it. So here we go. Power granted. And then the interface comes up. And then the line protocol comes up. We'll cover what that means later. And then the rest of the devices follow in suit. Now, how much power does a switch have? Because it doesn't have unlimited power. Let's check it out. So we're going to learn a new command here to check the power or PoE on a Cisco switch. The command will be show power inline, which I feel like I'm talking like Yoda. It's Cisco inline power, which, by the way, was the old stuff again. We're like, show power inline, will we? So let's check out show power inline. Bam. Let's scroll to the top here. Available on the Switch, we have 780 watts of power. With our three or four Cisco phones plugged in, we used 40 watts, and we have 740 watts remaining. Now, looking at our ports here, we can see that, hey, bam, each device is pulling, hey, look at that, 10 watts of power. We can see it's a Class 3 device, which if you look back at our Boson Corsair real quick, let's take a look. Class 3 takes between 6.49 and 12.95 watts. And we also see that each port is capable of outputting 30 Watts. Now quiz, what type of POE is that? What standard and what type comment below? Now, this might be confusing cuz it does say switch 79 60 Cisco phones are technically also a switch. They have a switch built into them. That's a topic for another time. I'll talk about that later. Phones are amazing by the way. Now I ran into an interesting problem when I was an engineer on this switch, you won't see that happen. But for example, This switch has 780 watts total available, and it only has 24 ports. If we do the math, 30 watts capable on each port times 24 ports, that's only 720 watts. So this switch has more than enough wattage to output power. I had switches that had a lot of ports, like 48 ports, but not enough to output full power on each port. So what happened to me is I actually had phones that would not power up on the floor. I mean, five or six phones that just would not work. As a new engineer, I was like, I was like, man, why is this happening? What's going on? And when I dug into the switch CLI and look at the Syslog, sure enough, that's what was happening. There's no power available and remaining. It was like zero and yeah. So keep an eye on this. Now I promised a real switch. We're going to do that right now. I want to plug in this big old hefty wifi six Cisco access point and your cable. I'll just use this naked one here. It'll still work. So I'm hearing my switch. I've got three POE devices plugged in. Let's do show power in line and see what's going on. So pretty much the same story available. Watts 67. We use 37.3 remaining 29.7. And then here's what our devices are pulling. So my 8841 Cisco phone here is only pulling 6.5 Watts. Even with this fancy screen, it's pretty cool. But then my access point here in my fancy camera, a full 15.4 Watts being pulled. Now, one last thing real quick, even though these ports are configured to send down 15.4 Watts to the device, The device isn't getting that full amount of wattage. It's actually probably getting around 13 Watts. Now, why do you think that is? It's the cable. We lose some power over the cable and the transport, nothing you really have to worry about, but that's what happens in case you ever wonder, okay, time for our boson XM for CCNA practice exam question. That's a long, a lot of stuff, man. This one might be a bit hard, but we did cover it in this video. So don't get too bogged down in all the wording. So here's the question. You have issued the power in line police command from the inter. face configuration mode on a Cisco switch, which of the following best describes what will occur when an attached PD attempts to draw more than its allocated amount of power from the configured interface. Select the best answer. Now, this again might be tough. And if you have to Google around and figure this out, do it. That doesn't mean you're dumb. That just means you're an it person. That's what it people do, but do attempt to answer it without Googling it real quick. So pause the video, go and we're back. Okay. I did cover this in the video. When we were taking a look at our Boson courseware, this first part might've tripped you up a bit, but we did talk about this. The answer I think is going to be C the port will enter an error disabled state and a log message will appear in the console. Let's see if we're right. Bam. Show answer. Yes. And then it'll explain to you why you were right or wrong. Bunch of amazing stuff here, man. POE or power over ethernet. It's amazing. I mean, God, let me grab this. The fact that we can send both gigabit internet down a cable and power blows my mind and we're doing more and more able to power larger devices. Pretty soon we'll only have PoE. We won't have actual power run through our houses, just all ethernet cable and I'm game for that. Anyways, that's all I have. Again, huge shout out to our sponsor, Boson Software. If you want to get your CCNA, CCNP or Security Plus or a bunch of other stuff they offer. Check them out, link below. They come highly recommended from pretty much everyone in the industry. If you wanna pass an exam, you wanna use their stuff. Anyways, that was CCNA episode 12. I'll catch you guys next time. you

Power over ethernet. P O E. It's kind of amazing. Why? Let me show you.

This is awesome. This phone right here. It's an IP phone to make this thing work. We need two things. We need power and we need internet and ethernet connection.

We can accomplish both those things with one cable. Here we go. Here comes my favorite sound in the world. Oh yeah.

And boom. With one cable power and data. So in this video, we're going to uncover unpack. Why this is so cool. I mean, obviously it is right, but we'll, we'll talk more about it and yeah, we're gonna get technical.

We're even gonna get down and dirty with our Cisco switch CLI and watch some power over ethernet happen. So yeah, you're gonna learn some stuff today. And shout out to the sponsor of our video and this entire series, Boson software. If you wanna get your CCNA, CCNP, A plus security plus, whatever they are the ones you wanna look to, to get prepared, practice exams, courseware labs, they got what you need. They are what I use to prep for my certification exams.

Check them out. Link below also. Let's see how smart you are. I've got a bonus question from their CCNA practice exam at the end of this video, it will be covering POE or power over ethernet.

So yeah, let's do this. Now we're going to start with the how and also the why, like why are we putting power over an ethernet cable? We'll get to that. But first the whole reason we even have POE, you can thank this device right here, the IP phone.

And it all started with my beloved Cisco. You see Cisco had these IP phones, right? And they're like, dang, I really hate running a power cable to this phone and an ethernet cable.

What if we could just mesh those into one thing? And they did. But, you know, it wasn't called PoE. Cisco had their own name for it. In the year 2000, I was 10 years old, Cisco invented Cisco inline power.

And it involves the same components you see here now. We've got our switch, and Cisco's like, man, let's beat this sucker up. Let's give it some power so we can power other stuff.

In PoE terms, we call this our PSE, or power sourcing equipment, because it is the source of the power. Sorry, that was going to happen eventually in this video. And then we'll take our ethernet cable, plug it into the ports, and plug the other side into our end device, which in our case right now is a Cisco phone, and that was the case back then. I have to label my stuff because I'm a horrible artist, so that's why I'm doing that. IP phone.

Again, in PoE terms, we call this our PD, or our powered device. Now, real quick, how? How are they putting power over this ethernet cable? That makes zero sense. Data, internet is going across this.

How are they also powering things? Well, back in the day, they just used the... Wires that weren't being used.

If you look back at our previous video in the series, we talked about ethernet cables and what each of these wires do with cat five cables and the cables before that we really only used two twisted pairs of wires on pins one and two and three and six. But then we had pins four and five and seven and eight that weren't being used at all. And Cisco was like, yeah, I got this.

We're going to send power over that sucker. We're going to power our phones. And they did that. Now, at this point in time, Cisco was the only player in the game, but that won't last long. When you invent something cool, it always has to become a standard, right?

Cisco knows that. So Cisco working with the I triple E, the people who make our standards brought in our first POE standard ratified in 2003 and comes 802.a F. Now this came with a few upgrades like Cisco inline power was rocking anywhere between like four and maybe five, six Watts of power enough to power a phone. For sure. Well, not this phone.

This phone has a fancy screen and all kinds of stuff. It would need more power and that's why we got more power. 15.4 Watts of power. We call this our type one. POE, or we still call it type one POE.

It's still around. We still use it. And now we have power for everyone.

That's a beauty of standardization. It's not just Cisco devices only. Now we can use ubiquity equipment, Aruba, Juniper, and all the other off brands. We can all play now.

Although what's funny, and you'll, you'll see this in a moment on Cisco devices, the commands are still Cisco inline power. It's like, they always want to remind us that they were the ones who invented it. And I can't blame them for it. It makes sense.

More power to you. Now we didn't stop there. We had a quest for more power and we got there.

And we'll talk about that. But before that, I want to talk about the why. Why are we putting power over Ethernet? What's the point of that?

What's wrong with the regular power cable? Well, there's nothing wrong with it. We're just, we're lazy. Any good IT engineer is really lazy.

That's why we automate things. That's why we have all of our technological advances. Because we're lazy.

Now, what do I mean by lazy? Think about this. Whenever we deployed an IP phone, this is before PoE or Cisco inline power, or an access point, our WAP, or even our security camera. cameras. We need two things, right?

We need power and we need data. We need internet. So to install all these devices in our buildings, this is gonna be my building here. Bear with me or my floor plan. This is my floor plan.

We might put a WAP here, here, just a random spots in the building, right? Or not random. Like we wanna get good wireless coverage and then strategically place our security cameras and such. And it becomes a huge pain to have to run both data and power. Cuz you have to have your network engineer run data, your cable, and you have to hire an electrician to run power.

That costs money and we're lazy. We don't want to do all that work. So the lazy engineers at Cisco were like, what if we could just do. Everything on one cable power and data.

And that's, that's why we have it now. So now our cameras and our WAPs and our phones can be powered and given data with one cable. And we don't have to involve electricians.

The network engineer can do everything. If we wanna move our WAP from over here to over here, it's just a matter of moving the cable or getting a longer one. Now back to our quest for power, because once we found out we could power phones and, uh, wireless access points and security cameras, we're like, what else can we do?

So we're like, we need more power. So in comes PoE plus. We always add a plus to everything to make it seem better. It kind of works.

I should come out with network chuck plus. No. The official name is 802.at.

This came out in 2009 and this doubled our wattage. We're talking 30 watts per ethernet port. That's hefty, man. That's crazy. We call this type two PoE and it's awesome.

We could power more devices, bigger devices. This is the most common standard by far. You'll see PoE plus everywhere. but the quest for power did not stop there. We need more power, double it, double it.

That's what we did. Sorry. I'm getting a little excited around 2011. Cisco said we want more and they went off the rails again. They came out with their own version of things. They called this U P O E, which stands for Cisco universal power over ethernet.

This was not a standard. This was Cisco only. And it was intense. Like we're talking 60 Watts of power. Like what are you gonna do with that?

That's a lot of power over an ethernet cable. Again, this happened in 2011. And this is where things got kind of cool because Cisco started using all four twisted pairs of wires to run power. That's how they were able to do this crazy amount of power.

So they were pioneers, but you know, it wasn't long before this became a standard. This goes by a few names. I've seen it POE plus plus. I've also seen four P P O E because they're using four pairs of wires, but the official name is 802.BT.

And if you're following along, we call this one type. What do you think? Three. Now what are you going to do with 60 watts of power? That's a lot of power.

Well, get this. We're actually using 60 watts of power to not only power phones and access points and security cameras, which by the way, I need to power up my security camera. I forgot to do that.

Oh yeah. Here we go. So not just these devices, we're also using PoE from a switch from one ethernet port to power another switch, which what, what?

Yes. We're using a switch to power a switch, which is really cool. Cause like, think about it.

you have this one big beefy switch because these are beefy. They have like massive power supplies to be able to offer 60 Watts per port, but this switch might be, you know, in a central location and then you'll distribute your other switches, your smaller access switches. You don't have to run power to those guys. They're being powered by the switch. It's crazy, but not as crazy as this next one.

No, no. The quest for power wasn't over. You didn't think it was over. Did you? No.

Check this out. In comes POE plus plus plus plus plus plus plus. No, I'm just kidding.

It's still called POE plus plus. I think, I don't know. It's still POE plus plus. and four PPOE and it's still called 802.BT. The only difference here is that we call it type four.

Now, what is it? What's special about it? Again, it's more power.

We want more power. We're talking 90 Watts now. What?

Like, what are we doing with that? We're going to power the building now. This happened in 2018, I believe.

And yeah, we're looking at powering some more stuff. And this is where it gets really interesting because we're not only powering phones and access points and and other switches. We're now looking at powering computers, like small computers for now, laptops over USB-C.

We can power lighting, like building lighting, like LED lights. Like think about that. Your smart lighting is getting your data and power from one cable. That makes sense, doesn't it?

And then even HVAC, air conditioning, powered over ethernet. I'm totally okay with the world where everything is powered over ethernet because that's just cool, right? And it's also safer.

Again, you don't have to involve an electrician. Network engineers can do this. and how much power put out is actually controlled by the switch in most cases, because there are two types of POE that I want you to be aware of. And I'm not talking about type one, two, three, and four are two types of POE. We have active and we have passive.

Now active is the cooler brother here. He's what we get excited about. He is what you're going to be using mainly on your Cisco switches and other brand switches, switches that run active POE will actually negotiate with the end device on how much power they're going to put out. Now, why do you think that's important?

Well, if you put out too much power to this camera here, it blows up. Like it doesn't blow up, but it fries. It doesn't work anymore. You have to output the appropriate amount of power.

So the switch will talk to the phone or camera or whatever it is. But how does it do that? How do they talk?

How do they speak the same language? Well, a standard like everything else. Now, again, Cisco came out with their own before anyone else did. It's called CDP or Cisco Discovery Protocol.

It's still used today. And basically what happens is you plug a device into a switch and they'll go, Oh, hey. who are you? Let's talk.

Let's find out what you're doing here, what you need from me. It's just like shaking hands and introducing themselves. Now we do have an industry standard version of that. That's called LLDP or link layer discovery protocol.

It does the same thing. And Cisco devices like switches support both. It'll default to CDP for Cisco phones and access points, but there's a device that supports LDP, which would be every other third party device.

It'll switch over to LDP and they'll use these two protocols to negotiate, Hey, how much power do you actually need? I don't want to give you too much. And I also don't want to give you too little.

So they talk it out and bam, they go about the day. Now passive does not do that. Passive is kind of stupid.

No, it has its place. Passive is always on power. So with active, I mean, you can plug regular devices into a switch that don't need power, like your computer and stuff. And the port will automatically go, Oh, this guy doesn't need any power.

I'm not going to throw power at it. He's fine with passive. That doesn't happen. Passive just says you're getting power.

You're getting power. You're getting power. You're all getting power.

It's like an evil Oprah. I don't know why the power's in my head. You'll often see this called 24 volt POE. It's not as popular because yeah.

Um, if you plug in a device that isn't supposed to receive power, um, and that much power. It's gonna fry. Now again, I haven't seen a lot of this, but a big name brand I currently use does support this.

Ubiquiti. A lot of their switches do have this, and you might be wondering, well, why would we even support that? Well, some devices need 24 volt PoE because they don't support that negotiation process.

And yeah, it's probably gonna end up being a legacy equipment that doesn't support that. But anyways, let me show you what my Ubiquiti switch looks like because it does support all of these types of PoE. So here is my Ubiquiti switch. I call it the golden snitch. And here you can see I have two PoE options.

I've got PoE plus and then 24 volt PoE. Now thankfully I don't have to worry too much about this. I can go into my individual ports here.

Let's take port two for example. I can click on this guy, overwrite his port profile, and change it from PoE PoE plus to either off or 24 volt passive. Now by the way, it supports PoE plus which means it'll support every PoE standard before that. Every one of these is backwards compatible so that's good.

So just watch out if you buy this weird switch that supports 24 volt passive and it's always on, be careful, check your stuff. Now looking at the boson core square here for the CCNA, which is amazing, by the way, you should totally check this out. They've got a great section on POE.

So if you want to dive a little bit deeper than what I'm covering here, check it out. It talks about things like, Hey, there are different classes of device power, zero, one, two, three, four. And what they are going to draw from the PSE or the power sourcing equipment. And they also offer this little nugget of wisdom right here.

Just some stuff that you should learn and commit to memory. If a device attempts to draw more power than a port is configured to provide what's gonna happen. A syslog message will be issued and the port will be shut down and enter the error disabled state. So things like that and memorizing the standards. So we talked about 802.AF, 802.AT, 802.BT.

Commit those to memory. What they mean, what types they are, how much power they put out. And again, that's per port. But anyways, enough theory.

Let's get our hands dirty. Let's get into the Cisco CLI. And by the way, I've got a lab in the description. below right now that you can play with and go along with me. So let's open that sucker up.

So here we are inside Cisco packet tracer, an amazing way to practice all your Cisco skills. I mean, it really is cool. What we're going to do is actually plug up some Cisco phones to a Cisco switch and we're going to see POE happen right now. Now we're going to demonstrate this here in this application, which is fake, you know, but then I'll show you here on a real switch.

So hang tight for that. But anyways, let's do our lab real quick. So first let's get into our switch.

I'm going to double click our 3650 here, jump in there. and go straight to the CLI tab. We are already logged into the Switch. I am gonna type in ENABLE or enable to get into enable mode.

You should have a pound sign right there next to your blinking cursor. And now what I want you to do is connect up your phones, each one, to the Switch, and then we'll check our Switch and see what happens. So we'll do that by clicking on our lightning bolt down here, Harry Potter style, which is our connections, and then go ahead and select the lightning bolt once more right here. And then we'll just start connecting. Switch to phone.

Let's click it again. Switch to phone, repeat, switch to phone, push the phone. And you can see by all the blinking that things are happening.

Let's go take a look at our command line real quick and check it out. I'll scroll to the top here real quick to our first few events. Our first syslog message here detected on interface one zero one power device detected I triple E PD or power device. That was like, yeah, we'll grant power.

We'll allow it. So here we go. Power granted.

And then the interface comes up. And then the line protocol comes up. We'll cover what that means later. And then the rest of the devices follow in suit. Now, how much power does a switch have?

Because it doesn't have unlimited power. Let's check it out. So we're going to learn a new command here to check the power or PoE on a Cisco switch.

The command will be show power inline, which I feel like I'm talking like Yoda. It's Cisco inline power, which, by the way, was the old stuff again. We're like, show power inline, will we?

So let's check out show power inline. Bam. Let's scroll to the top here.

Available on the Switch, we have 780 watts of power. With our three or four Cisco phones plugged in, we used 40 watts, and we have 740 watts remaining. Now, looking at our ports here, we can see that, hey, bam, each device is pulling, hey, look at that, 10 watts of power.

We can see it's a Class 3 device, which if you look back at our Boson Corsair real quick, let's take a look. Class 3 takes between 6.49 and 12.95 watts. And we also see that each port is capable of outputting 30 Watts.

Now quiz, what type of POE is that? What standard and what type comment below? Now, this might be confusing cuz it does say switch 79 60 Cisco phones are technically also a switch. They have a switch built into them.

That's a topic for another time. I'll talk about that later. Phones are amazing by the way.

Now I ran into an interesting problem when I was an engineer on this switch, you won't see that happen. But for example, This switch has 780 watts total available, and it only has 24 ports. If we do the math, 30 watts capable on each port times 24 ports, that's only 720 watts.

So this switch has more than enough wattage to output power. I had switches that had a lot of ports, like 48 ports, but not enough to output full power on each port. So what happened to me is I actually had phones that would not power up on the floor.

I mean, five or six phones that just would not work. As a new engineer, I was like, I was like, man, why is this happening? What's going on?

And when I dug into the switch CLI and look at the Syslog, sure enough, that's what was happening. There's no power available and remaining. It was like zero and yeah. So keep an eye on this. Now I promised a real switch.

We're going to do that right now. I want to plug in this big old hefty wifi six Cisco access point and your cable. I'll just use this naked one here.

It'll still work. So I'm hearing my switch. I've got three POE devices plugged in.

Let's do show power in line and see what's going on. So pretty much the same story available. Watts 67. We use 37.3 remaining 29.7. And then here's what our devices are pulling.

So my 8841 Cisco phone here is only pulling 6.5 Watts. Even with this fancy screen, it's pretty cool. But then my access point here in my fancy camera, a full 15.4 Watts being pulled.

Now, one last thing real quick, even though these ports are configured to send down 15.4 Watts to the device, The device isn't getting that full amount of wattage. It's actually probably getting around 13 Watts. Now, why do you think that is?

It's the cable. We lose some power over the cable and the transport, nothing you really have to worry about, but that's what happens in case you ever wonder, okay, time for our boson XM for CCNA practice exam question. That's a long, a lot of stuff, man.

This one might be a bit hard, but we did cover it in this video. So don't get too bogged down in all the wording. So here's the question. You have issued the power in line police command from the inter.

face configuration mode on a Cisco switch, which of the following best describes what will occur when an attached PD attempts to draw more than its allocated amount of power from the configured interface. Select the best answer. Now, this again might be tough. And if you have to Google around and figure this out, do it. That doesn't mean you're dumb.

That just means you're an it person. That's what it people do, but do attempt to answer it without Googling it real quick. So pause the video, go and we're back.

Okay. I did cover this in the video. When we were taking a look at our Boson courseware, this first part might've tripped you up a bit, but we did talk about this. The answer I think is going to be C the port will enter an error disabled state and a log message will appear in the console. Let's see if we're right.

Bam. Show answer. Yes. And then it'll explain to you why you were right or wrong. Bunch of amazing stuff here, man.

POE or power over ethernet. It's amazing. I mean, God, let me grab this.

The fact that we can send both gigabit internet down a cable and power blows my mind and we're doing more and more able to power larger devices. Pretty soon we'll only have PoE. We won't have actual power run through our houses, just all ethernet cable and I'm game for that. Anyways, that's all I have. Again, huge shout out to our sponsor, Boson Software.

If you want to get your CCNA, CCNP or Security Plus or a bunch of other stuff they offer. Check them out, link below. They come highly recommended from pretty much everyone in the industry. If you wanna pass an exam, you wanna use their stuff.

Anyways, that was CCNA episode 12. I'll catch you guys next time. you

Transcript for:Overview of Power over Ethernet (PoE)

Transcript for:
Overview of Power over Ethernet (PoE)