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Lesson 5.3 “How Networks Work” Objectives
2.5 Compare and contrast common types of input/output device interfaces.
2.8 Identify basic networking concepts.
Networking Models (5.3.1)
A network is created when two or more computers are connected.
The client-server relationship is a basic concept in networking. It's one way of looking at how one computer (a server) and another computer (the client) on the same network talk. The client requests information and resources, and the server fulfills those client requests. The servers are powerful, dependable computers that are expected to be available all the time, every day, without taking a break.
computers can have a peer-to-peer relationship model. It's a meeting of two equals. Both computers can request resources, and both can provide resources to fulfil those requests. Peer-to-peer architecture allows smaller groups to share information just as easily as groups with more computing power. Peer-to-peer architecture makes it easier to share files, stream video, and resist security threats.
The main network types you might pick from are local area networks (LANs) and wide area networks (WANs).
Local Network Types (5.3.2)
When a few computers or devices are connected together on the same network (like your home or school) it's called a local area network (LAN).
The LAN will traditionally be a group of connected computers that are physically close, usually in the same building.
These computers are linked up using a centralized device called a switch.
LANs can be small, like the Wi-Fi network at your house, or they can be much bigger, like in a large company. That's called an enterprise network. Setting up a LAN has lots of benefits. For example, every computer or device on this type of network can share resources with each other. The most important thing they can share is an Internet connection. They can also share files, printers, and anything else on the network itself.
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Local Area Network Examples
An intranet is a private LAN, a bit like a miniature Internet that's just for people in the same company or organization.
It works a lot like the Internet, but it's not part of the global Internet that everyone in the world uses.
Only people who with permission can get access. Intranets are great for sharing files and collaborating together at work.
You can share all sorts of things like documents, spreadsheets, or slideshows.
And these files are stored safely, can be backed up, and can be shared over and over again without the worry of being stolen by someone from the outside.
small office, home office (SOHO). This is a network made for a small business that you can set up in any office space or at home. The most important part of this setup is the router. A SOHO router can do more than the regular routers people have at home.
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Key Features of Local Area Networks
There are some primary elements that make up a LAN. First, there are one or more people called network administrators who oversee the LAN. These admins try to make sure that everything on the LAN is safe, and they decide who can use what.
A LAN network is typically very fast, because all the devices are close to each other. It uses network devices called switches and routers to connect all these close-together pieces. Switches help move data around, and the router manages the connection to the wider internet.
To keep everything secure, a LAN will also have firewalls put in place.
These might be built in to the router or be a separate device that stops hackers from getting in.
Security is important because a LAN also connects to the Internet.
One of the best things about a LAN is that everyone can share one internet connection, which means you only have to pay for one internet service provider (ISP).
And things like printers can be shared, so you don't need as many extra devices cluttering up space.
The sharing resources part is a huge benefit of learning how to set up a LAN.
Wide Area Network Types (5.3.4)
A metropolitan area network (MAN) links smaller LANs into one larger, centralized network. Think of it like this: if each LAN is a small neighborhood, then a MAN is a big city that connects all those neighborhoods together.
A MAN is bigger than a neighborhood but not as huge as a whole country (that's what a WAN is like).
You'll probably find MANs used mostly by colleges, big cities, or even by towns that are close to each other.
There are also wide area networks based in the cloud.
One example would be Amazon Web Services (AWS).
It uses the power of cloud networks to stay turned on almost all the time and has the flexibility to shrink or grow depending on what a specific company needs.
The Internet is really just a giant WAN that connects lots of smaller networks from all around the world.
The difference is that where many WANs are privately owned, the Internet is for everyone.
Networking Devices (5.3.5)
Modem
A modem is a device that takes the signals from your Internet Service Provider (ISP) and translates them into a form your devices can understand. It "modulates" and "demodulates" the signals, which is how it got its name.
A modem maintains your connection to the ISP. It sits between two networks, your own home local area network (LAN) and your ISP's network, and allows data to move between the two.
Usually your ISP will provide the modem for you, though you can purchase and use your own.
On the consumer side (that's your side) the plugs are made to be universal, so just about any device with a network connection can join up.
In most cases, the modem will probably come with a router as well,
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Router
A router is like a traffic light for the Internet in your house. It helps all your devices talk to each other smoothly, and gets the right traffic to the right places. Some people think routers just send data around your house, but actually, there's a specific part inside called a switch that does that.
Routers have Ethernet ports on the back where you can plug in devices such as your desktop computer. They also send out Wi-Fi signals so that your phones, tablets, laptops, and smart home devices, the ones on the Internet of Things (IoT), can connect to the internet wirelessly.
Routers are available in two different types:
Consumer routers: These are ideal for small offices or homes, because their signal strength is not very strong, and is best suited to smaller areas. Consumer routers offer both wired and wireless connection options.
Commercial routers: This type of router has both a stronger signal and higher capacity, making it perfect for large companies that rely on constant traffic management. Commercial routers offer only wired connections.
Routers have an area called the interface that you can access either on a web browser or with a command line interface (CLI). On the interface, you can set things up the way you want, such as giving your Wi-Fi network a name, or setting a password. Maintain your router by updating its firmware whenever a new version becomes available.
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Switch
Switches are like delivery trucks that move pieces of information directly to their destinations in a LAN.
Before switches, there were devices called hubs that did the same job, but without the same precision
They know exactly which devices are connected to them and can figure out where to send the right piece of information. They do this by looking at a special code called the media access control (MAC) address, which is unique to every device.
Switches can be small, with just 4 connection ports, or very large, with up to 96. Each port has an RJ-45 connection for your Ethernet cable.
Some switches can send electricity through the cables along with the data.
This is called Power over Ethernet (PoE). It's handy for devices like Wi-Fi routers, security cameras, and office phones that require power to work.
Some switches also have ports for fiber cables, which let data travel over longer distances.
There are two types of switches:
Unmanaged switches: This type of switch allows you to simply plug in an Ethernet cable, and it will work. An unmanaged switch does not allow for any type of configuration, or changes to its performance.
Managed switches: This type of switch lets the user control how it operates, or configure its settings. One example of this feature is the ability to set up a Virtual LAN (VLAN) on a managed switch. This allows you to make a small, separate network within a larger one. It's like having a private room in a big house, where only certain devices are allowed in.
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Firewall
Every network that connects to the internet needs to have a firewall.
Your home router has a firewall built in that acts like a shield between all the devices in your house and the internet.
Any business or organization, big or small, uses firewalls, too.
But theirs are typically much stronger and offer more features.
Firewalls are like filters. They let good data in and keep bad data out.
Firewalls can help by splitting the network into separate areas that keep critical systems sealed off from the internet. Additionally, they can manage virtual private networks (VPNs), which let data tunnel safely though the internet, encrypted.
Wired Network Connectors (5.3.6)
The cables that carry Internet data come in three types:
fiber optic cable,
coaxial (coax) cable,
twisted pair copper wire.
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Internet Service Providers (ISPs) use these different cables to bring the Internet to houses and businesses.
inside a house, you'll mostly find the twisted pair copper cable because copper is what Ethernet cables, or network cables, are made of.
These copper cables can't carry data as far as coax or fiber optic, but they are much easier to use.
Inside an Ethernet cable, there are eight wires grouped into four twisted pairs.
Each pair is assigned a color: orange, green, blue, or brown.
One wire's insulator (the plastic covering) is mostly white, striped with the color, and the second wire has an insulator with the solid color.
When you're ready to connect the wires, you need to untwist them and line them up in a certain order in the connectors.
This order can follow either the T568A or the T568B standard.
The order of the colors is important because devices can't communicate properly without the correct alignment.
In T568A, the green pairs are wired to pins 1 and 2, and the orange pairs are wired to pins 3 and 6.
In T568B, these pairs swap places, so orange is terminated to pins 1 and 2 and green to 3 and 6.
It's important to avoid using a mixture of the two standards.
T568B is probably the more widely deployed of the two.
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Making Cables
You can make Ethernet cables yourself with some tools and a little bit of know-how
Raw cables are sold in lengths of 100 to 1,000 feet.
You can then cut these lengths to the exact size you need. After cutting, you'd either attach RJ-45 clips to the ends, or connect the cable to a wall jack.
Here are some of the basic tools needed to make your own Ethernet cables:
Crimper: A crimper is a tool that helps connect an RJ-45 cable to its clip. To do this, you first make sure that the eight wires inside the cable are in the right order according to the T568 standard you're using. Then, you put them into the clip, and next, into the crimper. You squeeze the crimper to secure everything together. After you've done this on both ends of the cable, you should use a cable tester to check if all the wires are set up correctly.
Punch Down: A punch down tool is used to push each of the eight wires into a patch panel or a wall jack. When you press the cable into the right spot with this tool, it makes a satisfying click sound. Before you start punching, it's very important to check that the tool is facing the right way so everything is done correctly.
Cable Tester: A cable tester checks if a new cable, or one already connected to a patch panel or wall jack, is working. It quickly tells you the status of each of the 8 wires. The tester uses lights or an LED screen to show you the statuses so that you know if the cable was made in the right way. More complex testers can even tell you how long a cable is.
Toner Probe: A toner probe is a useful tool for figuring out where a network cable starts or ends. It comes in two pieces. One piece plugs into the network, usually at a wall socket, and emits a sound or a tone (that's why it's called a toner). The other piece is the probe, which you move over the various network cables to listen for that sound. This helps you determine which cable goes with which port. It's a big time-saver, especially when the network cables aren't clearly marked.
Wireless Network Connectors (5.3.7)
An access point (AP) allows wireless or mobile devices to connect to the network.
The AP can connect to the network using a cabled connection, and can provide wireless connections to other devices such as smartphones, tables, and laptops.
When you have several APs working together, it's called a mesh network, which works great for covering large areas with Wi-Fi.
Most of the time, enterprise APs are connected to the main network with an Ethernet cable. But the ones you might have at home usually just pass the Wi-Fi signal from one AP to another without cables.