Join Lazaro Diaz for an in-depth discussion in this video The basics of networking, part of Cisco Certified Entry Networking Technician Essential Training.
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- Alright, so how does one computer communicate with another computer across a network? We're gonna go ahead and use the Cisco Packet Tracer to visualize communication between two computers. So what I'm gonna do is on the bottom left-hand corner I'm going to select the Switches category, and on the right I'm gonna get a 2960 switch, I'm gonna click and hold, and drag it onto the white area or the work space of the Packet Tracer. And then I'm gonna go back down to the bottom left-hand corner under End Devices, and I'm gonna select two generic computers, one at a time.
Click and hold, drag it out, go back down, click and hold, and then drag it out. Now we need to connect these two devices to the actual switch. How do we do that? Again, in the bottom left-hand corner we select the lightning bolt. The lightning bolt gives us all sorts of different cables. What we're looking for is this black solid line, which is a Copper Straight Through. I'll click on it, then you see this little weird little looking thing here on the screen now. We're gonna click on the computer, Copper Straight Through, and you can see as you drag or you move your mouse towards the computer that the icon has changed.
We're gonna select PC4, and then select the Fast Ethernet port, and then we go to the Switch and select whichever port. I like to pick Port number 1. It doesn't really matter which port you choose. And then we go back down, select the same type of cable, the solid black line, which is a Straight Through, a Copper Straight Through, click on the second PC, click on Fast Ethernet port, and then click on the actual port that you wish. In this case I'm gonna click on Port number 2. Now, in order for them to communicate they need IP addresses.
That's why we stated earlier that it's important that you should know this. To assign an IP address to a computer just click one time on the computer, go to the Desktop tab, and then you will see IP Configuration. You click on there, and then in the IP Address text field you're gonna put in the IP Address 192.168.1.1 Of course, you're more than welcome to use the same scheme that I'm using unless you already know an IP address and can use your own scheme. Now all I'm gonna do is hit the Tab key, and it's gonna go ahead and put in the default mask for that particular class of IP address.
Alright, so, which is a Class C, this again, head's up, I'm gonna close, I'm gonna close again. Now I'm gonna go to the other PC and do the same thing. Click once, go to the Desktop tab, go to IP Configuration. IP Address is 192.168.1.2. And I'm gonna hit Tab key again, and then I'm gonna close. There is no Save button, not a big deal. It already gets saved by default. Now, instead of just pinging ourselves from one location to the other, I want you to see exactly what happens.
How do they communicate. So on the bottom right-hand corner behind where it says Realtime there's something called Simulation. You click on that. And then we have two envelopes. We have a Simple PDU and we have a Complex PDU. We're gonna choose the Simple PDU, which I like to call it Closed Envelope. You click on it, and you see it comes with you, and we're gonna click on one PC and then click on the other PC. And if you notice on the right side where it says Simulation Panel there's two things, ICMP and ARP, and I'm gonna explain a little bit of it as we go through it.
And we're gonna go down, I'm gonna click on Auto Capture / Play. And what is it that you're looking at. You're looking at a green envelope going across. Well that green envelope on your Simulation Panel on the right is an ARP, an Address Resolution Protocol. It's asking the other PC, hey who's the owner of this IP address? And it comes back with it's MAC address. That way it can complete both. Now we'll learn more about ARP in future lessons, but right now it's just to get the understanding. And now you see a blue envelope going across, which is the actual ping, and that is how two computers communicate across a network.
- The basics of networking
- The TCP/IP model vs. OSI model
- Understanding the Cisco three-layer model
- Collision and binary domains
- Converting binary to decimal and hexadecimal
- IP addressing
- Diagramming summarization
- Working Cisco IOS
- Managing Cisco internetworks
- IP routing
- Security with ACLs
- Configuring and verifying NAT
- IPv6 addressing