This is day one of my free CCNA course. And a huge shout out to Boson Software, the official sponsor of this CCNA course. They are the reason this can be made available for free, so I highly encourage you to go check them out. They have the absolute best CCNA, CCNP, labs, and practice exams. Day one, we're not wasting any time.
We're getting right into what is this? It's a switch. How does it work? Why is it amazing? Cause it is amazing.
And we'll even get a chance to lab. What does labbing mean? We will find out we're gonna use Cisco packet tracer to analyze frames and packets going across the network. And you're gonna get a chance to enter your first Cisco CLI command. Let's get started.
In my last video we talked about what a network is and we followed a Call of Duty bullet when I shot it from my computer How it goes through my home network to my brother's network and shoots his character and we went high level like router switch firewall access point What are those things but we didn't go too deep But now are you ready? We're gonna go just a little bit deeper It's just like one of those red pill blue pill situations from the matrix after this There is no turning back you take the red pill you stay in Wonderland And I show you how deep the rabbit hole goes. You take this pill. There's no going back.
We're going deep into the networking rabbit hole. You're gonna fall in love and never look back. Okay, I warned you.
You're still watching this, that means you wanna keep going. Let's do this. Okay, let's talk about switches first.
What are they and what are they doing? And here's one right now. This is a Switch.
It's beautiful, isn't it? Look at this. Oh, love it.
Now, if you watched our last video, you have a high level view of what a Switch is for. What's it doing? Well, it's helping our computers to connect to each other and talk and hang out and chat, send data. We connect using these ethernet cables and we plug them into our ports. Oh, love that sound.
Here, listen to this up close. ASMR version. Oh, one of my favorite sounds.
So we connect one computer, connect another computer and assuming we have computers on the other ends of these, they're talking, they're having fun. They're playing games, but what's really going on inside of here. Let's pop the hood. Let's take a look on by the way, switches can come in many different sizes.
Like this is an eight port and this big boy is a 48 port. He's beautiful. Ho ho ho ho.
Why do you need 48 ports? Well, so you can connect 48 different devices to each other. That's why. Now let's first look at this guy, the ethernet cable.
All it is is a bunch of metal wires. Like check it out. your computer communicates with the other computers via electrical signals.
And these electrical signals go down these wires through the cable to the switch. And then it goes to the other computer. It's amazing. It's just electrical signals going in and out of these ports.
It's, isn't that cool? Now switches are amazing, but for you to really appreciate how amazing they are, you need to look at their predecessor, the one that came before them, the hub. He's disgusting. He's dumb.
He doesn't have any smarts. The switch is smart. The hub is not.
But before we had switch, switches hubs are all we had and here's what they did and why they're dumb. Now I want you to actually see how dumb this is and experience it for yourself. So right now, what I want you to do is go download Cisco packet tracer. I've got a link below sign up for a free account through net cad, and you'll be able to download it.
What is this? It's a tool that lets you build and play with networks and so much more. It's amazing.
So go download and install that it's on windows, Mac, Linux. And once you install packet tracer, I've got another link below for a packet tracer file, which is a lab I built that we can play with right now. So go ahead and download that. and launch it.
Do not get overwhelmed with all the buttons and options here. I'll walk you through every step right now. If you zoom in right here, I've got two networks. I got this one here, which is a switch and my laptops.
If I scroll over, I've got another network and it's not nearly as smart because I'm rocking a hub. Now a hub and a switch physically kind of look the same. They look like this.
They have ports where you can plug ethernet cables into, but they're so, so different. Actually, we can look at a hub right now. Let me click on the physical button up here.
I can click on my home city, my corporate office. And then jump into my wiring closet. And there it is. So you can see switch, it's got ports, hubs, got ports.
Okay. But why are they different? How would you like this? If when you sent a text to your friend, it didn't just go to your one friend, it went to all your friends. And then when your friend responded back to you, it only went to you, but it went to all your friends as well.
That's stupid, right? Like that, I would never use that texting platform. That's what a hub does.
Check this out. And I want you to do this with me. So click on simulation down here at the bottom, right?
This is what makes packet tracers so cool. We can analyze the network traffic slowly as it goes through the electrical wires. It's, oh, it's powerful. Anyways, so don't touch that.
Leave it there. I want you to click on Harry Potter up here, laptop Harry. Then click on desktop, and then click on command prompt. This is very similar to a Windows command prompt.
It kind of is a Windows command prompt. And what we're going to do is we're going to have Mr. Harry here talk to Ron over here. Through the hub. We're going to send a message that we use in networking all the time called a ping message. What is that for?
We use it to see if other computers or servers are up and can be reached. Kind of like this. Ping! We found!
Ping! Ping! Now you may have noticed I've got a couple things right here.
Layer 2 address and Layer 3 address. Now what's an address? Well, if I wanted to send you a message, I might send it to your email address. If I wanted to send you a letter, I might send that to your...
mailing address. It's something unique to you that allows me to send something to you, data, whatever. And in the networking world, it's the same thing.
Now, what does layer two and layer three mean? We'll cover that here in a bit, but just know that when I'm going to send a ping message to Ron, I'm going to be looking at his layer three address that might look familiar to you. What is that? Well, that's an IP address. You're probably familiar with that, right?
Harry knows that when he wants to talk to Ron, that's his address. That's his phone number. That's his mailing address.
That's how he gets information to Ron, his IP address. So here we go. We're about to ping Ron. Now please make sure you have the simulation button checked. Not real time.
You want simulation. Here we go. Get your command prompt open.
We're gonna ping Ron. So I'll type in ping and then Ron's IP address 10.1.2.3. Now watch what happens when I hit enter.
Boom, a little envelope popped up, a little message we're gonna send to Ron. And then notice over here, we have a little event timeline where that message just popped up. We can see the play by play here as we get more advanced and go deeper and deeper into what's happening, which actually happened in the next video. we can click on these and look at some hairy details like what's happening.
Don't worry about that yet. We'll get into it, but it's amazing. So Harry wrote his letter. He's ready to send it. And if we click on this little advanced button right here, it'll take a step forward in time.
Let's go ahead and do that. Click advanced. Boom.
Let's do it one more time. Boom. There it goes.
It's going across the network. Electrical signals firing. So now the hub has the message in an ideal world, in a perfect world. The hub's like, okay, well, this message is for Ron. I'm going to send it to Ron.
But the hub's an idiot. He's dumb. Watch what happens. Watch what happens. Click next.
And why did you do that, Mr. Hub? You sent the message to everyone. Harry's just trying to talk to his buddy, Ron. And now Hermione knows and Malfoy knows. That's bad, right?
Now watch what happens next. Remember, in a ping situation, Harry's going to send a ping. Hey, you there, Ron? And Ron's going to go, yes, I'm here. But watch this.
Click next. Ron does reply. Perfect. but then watch what the hub does.
The dummy hub. He sends Ron's replied out to everyone. Why hub? Why?
Well, again, the hub has no smarts. He's got no brain. His job is just to repeat that electrical signal.
Whatever your computer sends down this wire, the hub's going to go and send out to everyone. This is how we did things for a long time. Now notice that over here, Harry Potter's got a green check Mark going.
Yes, yes, yes. That message is for me. Yes, yes, yes.
But then down here, Malfoy and Hermione have this X, which means that most of the time. In a hub environment, if a computer got a message that wasn't meant for them, it would just ignore it. But you know, that's if you're a good person.
If you're a hacker, like I'm learning hacking right now, if you get a message like that, if you're able to see everyone's traffic, you're like, yes, yes, give me more. I'm going to hack all you guys. Not a very safe and secure environment. You don't want to text your buddy something secret and all of a sudden all your friends know the secret.
But now, let's look at the switch. He fixes everything. Go ahead and click on reset simulation.
You can close out Harry Potter there. And let's scroll on over to the better environment, the switch environment. Now here, the switch has the same goal as the hub, just to connect these computers together so they can talk.
So they're doing the same job. Just one's really, really good at it. So over here, let's walk through the same situation. Johnny right here is gonna ping Mark.
Oh, hi Mark. And we'll see what happens and I'll explain how it happens here in a moment. So go ahead and click on Johnny, click on the desktop tab and then jump into your command prompt.
We're gonna type in ping and then Mark's IP address right here is 10.1.1.2. We're going to hit enter and bam, Johnny's got a message ready for Mark. Let's click on next and see what happens next.
Next. Okay. There it goes. The switch has it.
What's it going to do? Boom. So much better.
Only Mark got it. And then when Mark responds, it only goes to Johnny. That's how it's supposed to work. Thank you, Mr. Switch.
And if you look back at our command prompt, you can see that we sent a ping message and then we got a reply from Mark from the IP address. Everything's good. Mark's alive.
He's like, Hey, yeah, yeah, Johnny, I'm here. And if we click on real time, it'll just complete it like it normally should. Bam, bam, bam, really fast.
Because these electrical signals are going really, really fast down these wires. But that's what's cool about packet tracer. We can slow down time, bullet time and watch it happen. Okay, we're about to go deeper. We're about to learn more about how this guy does things.
Are you ready? Let's take a deeper look. The switch can do all this magic because it has a brain.
A brain that can remember things like, hey, on my port FA02, that's where Johnny lives. And on my port FA01, that's where Mark lives. And the same thing goes for Denny and Lisa and anyone else who connects to the switch.
He'll remember where they are. So when you send a message, he'll go, oh, well, I know exactly where Johnny is. He's over here.
Port FA02. He stores that information in something called the CAM table, which stands for content addressable memory. Don't worry about that too much right now.
We'll cover a lot of that later. Now the switch doesn't know Johnny as Johnny. The switch knows Johnny as 00D097528936. That's how the switch knows Johnny, his layer two address. That's how the switch knows Mark.
He doesn't know Mark's name, but he does know 00E0B0590897. Love that guy. What are these things? That's called a MAC address. often referred to as a layer two address.
Every single device that you connect to the internet has a Mac address, every one of them. Like go ahead and look, get your laptop out, look for it. Like on this phone here that I would connect to the switch. Look right here, there's my phone's Mac address right there.
It's often referred to as the burned in address because this address should never change. That's how your device is identified. It's unique identifier.
So when I connect my phone to the switch and my phone tries to talk to somebody, boom, the switch learns, hey, that phone, which. That phone's name is 9C578003844A. He lives on port one. So if anybody wants to talk to him, it's gonna be port one. Now we'll cover more about layers here in a moment.
I'm kind of building up to that. But this right here, doing this, and that wonderful, beautiful sound, yes. This is layer one.
Anything physical, the electrical wires, the metal wire, that send electrical signals down into the switch, that's layer one. So layer one, electrical signals firing at light speed down an ethernet cable. physical.
And then we get to our switch and now we're thinking about layer two. And that's where our layer two address comes in. That's where the Mac address comes in.
Layer two is often referred to as the data link layer, but we won't cover too much on that right now. I have to stop. I don't want to give you too much right now.
Now you may be wondering why isn't the switch just using the layer three address like what we used when we pinged 10.1.1.2. Why doesn't the switch know marked by that number? Well, the simple answer is that the switch can't even see that number.
It has no idea what it is. You see the switch is a layer. two device and doesn't know anything about layer three or IP addresses or anything.
That's why we're dealing with Mac addresses right now. Now watch this. Let's get back to our packet tracer.
We're going to do a couple of things here real quick. Let's click on simulation mode once more and let's open up Mark. We'll go to his desktop, go to his command prompt, and we're going to ping Lisa down here.
So we'll do ping 10.1.1.5 and hit enter. The message was built. Now go and click the forward message real quick. And I want you to click on this, this message right here.
We have click on it. Now, as you can see, we have seven layers. We're gonna be talking about here very soon, but don't, don't think about anything above layer three right now. Don't think about that, but notice this message we're sending to the switch. Notice what's not there.
Layer three is missing. It's just layer two because that's all the switch understands. And also notice the to and from. So right here we have the from, which is the Mac address of Mark over here. And then the two is to Lisa's Mac address down here.
And if we go ahead and step forward in time, boom, the switch receives it. If we click on that message again, we see that the switch receives it and he knows exactly where to send it because he remembers where Lisa is. And then if we click on that button, bam, it goes to Lisa. Now I'm not sure if I want to show you this yet. Yeah, let's go ahead and do it.
So click on that envelope right there. The message that just arrived to Lisa, you can see here that instead of just having layer one and layer two, we now have layer three involved because that's a layer that Mark and Lisa are talking on layer three. You see, we pinged from Mark's IP address 10.1.1.2 to Lisa's IP address of 10.1.1.5. And then Lisa sending out a message, see out to mark at 10.1.1.2 from herself, 10.1.1.5. And then we step forward in time once more, boom, we see this message go to the switch.
But then if we open that message, Oh, layer three is gone again. It's just layer two because that's all the switch cares about is layer two. And that's how he knows where things are. That's where devices are based on their Mac address.
Now go and click on real time, let that finish out. And we're going to jump into the switches command line interface. And this might be your first Cisco command.
Kind of exciting. So let's, let's open it up. What we're going to do is we're going to look inside the switch's brain. So go and click on him and jump to the CLI tab. This is a whole new world for you.
Yes. Okay. Now hit enter, then type in enable and hit enter.
Now you should have a hashtag sign right there next to your switch. Here's a command I want you to enter show Mac dash address dash table. We're looking inside the switch's brain and looking at his cam table.
where he keeps the Mac addresses and how they are assigned to the ports because Mark and Lisa just talked the switch knows that Mark, which is referred to as blah, blah, blah, Mac address lives at F a zero one. And then Lisa lives at F a zero three. And then if we go to Denny over here and we go to desktop and command prompt, and we try to ping Johnny 10.1.1.3, it's going to go through. It's being successful.
Awesome. We jump back into the switch and hit the up arrow to enter the same command. Hit enter.
Well, now the switch knows where everyone is. He knows where Johnny is, where Denny is, or Mark and Lisa. He learned it, stored it in his brain. And now whenever someone sends a message, he goes, I know exactly where they are. Boom, right there.
The hub just doesn't do that. And that's the job of the switch. He learns where everyone is by learning their Mac address, their burned in address and stores that in his brain, in his cam table and marks where they are. So whenever he receives a message, he can forward those messages to the appropriate people and not to anyone else that shouldn't hear about it. Now, when we're talking about layer two, This message right here is referred to as a frame.
All the messages going through this switch right here are frames. Boom, boom, boom frames is going around like crazy because it's layer two. When you think layer two, think switch, think frames, switch frames, layer two, switch frames, layer two. Is it working? Is it going in there?
But then when the message goes to Lisa and we're talking about IP addresses in layer three, do you know what it becomes? This message is now a packet. Now just so you know, when you're talking to network engineers and other folks, They might refer to layer two messages, the frames, they might call those packets as well.
We just get in the habit of it. If it's going across the network and it's going to people and it's a message, we often just refer to it as packet. It just happens.
But technically, it's frames. Layer two frames switch. Layer two frames switch. Okay, now we're gonna talk a little bit about wireless. Here's a wireless access point, a little baby Cisco one.
Here's a bigger Cisco one. The reason I wanna talk about them now along with switches is because they're basically doing the same job as a switch. But what's funny, What's funny is they're more like a hub than a switch. They're kind of dumb.
I mean, they're amazing, but they're kind of dumb like a hub. Let me show you. Looking back at packet tracer.
If I scroll down just a little bit, you can see I have a little wireless network here. Let me add the IP addresses here real quick. Now what I want you to do real quick is down here at the bottom, click on the lightning bolt, very Harry Potter esque.
And then click on the lightning bolt again. This is a connection. It's like plugging an ethernet cable and we're going to plug it into the access point here and then plug it into our switch.
We talked a little bit about wireless in the first video, but it's just an extension of the switch. So it connects to the switch with an ethernet cable and then it connects all the other devices via wireless, which we know to be airwaves or radio waves. So most of our devices like our phones and everything else connect to this access point, which is connected to a switch.
Now even though this access point is connected to a switch, he's actually more like a hub and it's all about these connections right here. Let me show you real quick. I'm going to have Mr. Denny here.
I'm going to click on Denny and launch his laptop. We're going to go into his desktop and go to his command prompt and we're going to ping. Let's say the first tablet down here, 10.1.1.11. So I'll do ping 10.1.1.11. Oh, I forgot to go into simulation mode.
Let's go into simulation mode down here, bring Denny back up and boom. So as you can see, Denny's got his packet ready and he sends this frame to the switch. Now if we open up that frame, what do we see? Well, we see that the source is indeed Denny over here based on his Mac address. And then the destination, well, what does that matching?
Well we scroll down here and we can see, yeah, it does match the first tablet here. So the switch knows that he lives on this port connected to the access point, but it's what the access point does with it. That's so stupid, but it's just how wireless is right now.
Let's skip forward in time. The access point has it now, but now let's see what happens. Click next.
Boom. And once more, boom. The message was sent to everyone like a hub. Now we'll cover wireless in more detail here later in this course, but just know for now, that's why people tell you plug into an ethernet cable at all costs if you can, because a wireless connection is more like a hub. And the fact that all the messages are going to each device, isn't the worst part with hubs.
It's just a traffic jam collisions all the time, which is why switches are great. And we'll cover more on that later. But yeah, always prefer ethernet cable, a hard line connection to a wireless connection if you can now later versions of wifi, like wifi six, do help out with this. I actually made a video on Wi-Fi 6 that you can check out up there.
And then as we step forward in time, when the first tablet sends his reply back, the access point will then send it to the switch. And then the switch, like it's supposed to, will just send that to Denny. But then we have the same process that happened again when Denny does send another ping.
Hey, hey, first tablet, are you there? The access point will still broadcast that out to everyone. All right.
Hope you have your coffee ready. Time for a quiz. Time to test your knowledge and what we just covered in this video. The questions I'm about to ask you are not easy.
I pulled them from Boson XM, the best CCNA practice exam you can find. They are world-renowned, and they are sponsoring this video, so check out the link below for that exam. Anyways, let's see what you know. Question number one. Which of the following addresses will a switch use to populate the cam table?
Select the best answer. If your answer was B, Source IP address. You are wrong because the answer is in fact, D source Mac address. Remember Switches, layer two, Mac address. Switches, layer two, Mac address.
Let's select our answer and get the deep down dive from Boson. So right off the bat, because we know we're talking about a switch in the cam table, we can mark out A and B because those are talking about IP addresses. And the switch doesn't know anything about IP addresses.
But what we're talking about now is Mac addresses. Now it could have been source or destination. A switch will learn a Mac address and add it to its cam table when a device sends a frame to that port.
And in that frame, the source Mac address... will be this guy's MAC address. So that makes sense.
Destination would be who he's sending that frame to, which might be a person over here. And you wouldn't want to add this guy's MAC address to this guy's port. Confusion, it wouldn't work. If you got that right, that's amazing. You're just a little bit closer to passing your CCNA.
Next question. Which of the following addresses will a switch use to make forwarding decisions? Select the best answer.
If your answer was destination Mac address, then you are absolutely correct. Let's select the answer and see if Boson thinks I'm right. Here is Boson's wonderful explanation.
I encourage you to pause the video and read that. But looking at the question, it's talking about a switch making forwarding decisions where we can automatically say, you know what source IP addresses out destination IP addresses out because again, switches don't know anything about IP addresses. Now when a switch receives a frame from a device, this frame will have a source Mac address. let's just say zero zero zero one and a destination zero zero zero two.
The source is coming from this guy. That's his Mac address. He's trying to send it to the destination Mac address.
This guy who is probably over here. And this question explanation is perfect because it piggybacks off the previous question. The switch will not use a source Mac address to make forwarding decisions. However, it will use it to populate the cam table. Again, if you got that right, congrats, you are even closer to getting your CCNA.
And if you didn't, it's fine. go back and watch the video. Learning is a process.
It's a day by day thing. Adding to your knowledge. You'll get there.
Trust me. Didn't I tell you? Switches are amazing. And we, I know I keep saying this, have just scratched the surface.
And in this video, we covered some ground on how switches work. You even got to work in packet tracer and watch packets and frames go across the network. You may have even issued your first Cisco CLI command, which is amazing.
Write that down. Today was your first command. Show Mac address table. You. Look inside the switches brain inside his cam table to see the Mac address to switch port assignment.
That's huge. And guys, that's about it. We just covered day one switches in the coming videos. We'll be talking about routers and we'll be talking about the other layers of the OSI model, which we kind of talked about layers one, two, and three today.
We'll cover the rest soon. And you're going to love it. Trust me. If you like this stuff, you will love, love that stuff. And again, huge massive shout out to Boson software for sponsoring this CCNA series.
They're making it free. So I encourage you to go check them out. They have amazing labbing software.
So what I showed you today was Cisco Packet Tracer. It's great for demonstrating to you how a network works. Boson NetSim is a great lab software that will allow you to go through labs and also get deeper into like Cisco command line stuff where it gets pretty, pretty sophisticated, pretty complex.
They have fantastic labs that walk you through things. They'll grade you on how you do, and they'll even explain everything. It's awesome.
And then of course, the practice exam questions I showed you today. That's from their practice exam and ask around their exams are golden if you can pass their exams You can probably pass the CCNA many people say bosons is actually harder than the real CCNA So links below for that again. They have their summer sale It's 25% off if you have any questions or comments Please let me know below and if you like this video like it hit that subscribe button and hit that Bell notification Icon to be notified when I post stuff.
This was CCNA day one. See you on day two