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What is a Network and what does it consist of?






A network is a collection of devices (two or more) that share information between each other. When you think of devices, think of anything that you can communicate with. Examples are like a cell phone, a laptop, a desktop, printers, fax machines, pagers, etc. These devices communicate with each other in one way or another. They simply share information.


The information that is shared, can be a number of things like sharing email, instant mail like chat rooms, voice communication, files like software, etc.


When devices share information with each other, it can be done hard wired with cables or wireless over radio waves. This can scale to just two devices or multiple devices. This can also be done locally like in a home or office building and it can also be done in a wide area like two or more office buildings sharing information between each other.


The connection between network devices are either wired or wireless. In terms of wired communication, we are referencing cables. Devices connected via cables. Now before we jump into cables, let's dive a little deeper into wired and wireless connections.




A wired connection, the most common connection, is commonly referred to Ethernet. Ethernet is a technology consisting of data being transmitted through wires or cables. The standards of using Ethernet is governed by the IEEE (Institute of Electrical and Electronic Engineers) via a document called 802.3.


IEEE, an association dedicated to advancing innovation and technological excellence for the benefit of humanity, is the world's largest technical professional society. It is designed to serve professionals involved in all aspects of the electrical, electronic, and computing fields and related areas of science and technology that underlie modern civilization. IEEE's roots go back to 1884 when electricity began to become a major influence in society. There was one major established electrical industry, the telegraph, which since the 1840s had come to connect the world with a data communications system faster than the speed of transportation. The telephone and electric power and light industries had just gotten underway.

A wireless connection allows devices to connect to each other but just over radio waves instead of physical cables. This provides more flexibility when moving your device around. For example, let's focus on a cell phone or a tablet. When you want to browse the web, you don't connect wires to it. It simply connects to the internet via radio waves thus allowing you to roam as you wish. The IEEE regulates this technology via a document called 802.11.


Before you can dig deeper into networks, understanding what a basic network consists of, is important. A simple network, for instance, your home office is pretty easy to set up. Let's start with the most important part, the computer. Most people think the monitor is the computer but in actuality, the tower your monitor is connected to is the computer. You either have a desktop computer or a laptop computer. As technology advances, we are seeing more monitors that include the computer parts which removes the need for a tower.



Now, whether you have a laptop or a desktop, it will have a network interface card (NIC) built in. Unless you are tech savvy and want to build a computer from scratch, then you would buy a NIC and install it. If you are interested in what a desktop computer looks like inside, see my video on "How to build a computer".


NIC (Network Interface Card)


From the computer (in terms of a wired connection) you will need an ethernet cable. This cable will route from the back of your computer to router or modem. If you are using a wireless connection, clearly you don’t need this component.


Lastly, and very vital, you will need software. Again, if you bought a computer 99% of the time it will come pre-installed with a software, whether it's Windows operating system or MAC operating system. Tech geeks sometimes install other operating systems like Linux. On your mobile devices, you will have something like Android or iOS installed.

By now, you know what a network is and what it consists of. It's time to dive a little deeper and discover the different types of networks.


There are many different types of networks. Let's briefly discuss some of the most common network types.


Personal Area Network (PAN) is just like what is sounds, personal. This type of network is managed by one person and usually found in residences, like your home. A PAN includes your computer, wireless modem and a mobile device like phone or tablet. Even small businesses use a PAN.



Local Area Network (LAN) connects groups of devices together across short distances (within a building or between buildings that are in close distances). These networks are managed by enterprises



Wireless Local Area Network (WLAN) is just like a LAN but wireless. They use wireless technology like Wi-Fi for devices to connect to them.



Campus Area Network (CAN) is another network that straight forward in it's name. They are typically seen in school districts like universities. CANs are just like LANs but are a little larger



Metropolitan Area Network (MAN) is a hybrid of both LANs and WANs (Wide Area Networks). They are used for devices in a geographical area like an entire town or city. MANs are managed by a company but can be managed by a single person as well.



Wide Area Network (WAN) is larger and connects multiple LANs together. They are managed by service provider companies like a phone or cable company.




Virtual Private Network (VPN) is the last network we will discuss and they allow devices to share information over a private network. VPNs mask their IP addresses from the public for secure connections



There are more network types but these are some common ones. The most common ones that you would see in the networking world are LAN, WAN and VPN. Either your network would be a LAN or a WAN and may include a VPN. Regardless of the type of network, devices need to share information with each other and are categorized by their size and connection type. Alongside network types, networks are also classified by their topology and architecture.


A topology is the physical or logical layout of a network in terms of data links or the arrangement of devices. When you think of a topology think of a diagram of how the devices are connected to each other. That connection can be a physical connection for example, one device centrally located and all other devices connect to it. It can also be logical whereas that same central connection is described by signals.


There are six types of topologies in a network. Let's go ahead and discuss them.




Bus topology is a single communication line for data transmission. It is the first topology used and simple but signal collisions can occur and they are not efficient.


Ring topology consists of devices that are arranged in a circle design. It's similar to a bus topology but a closed loop. They are not used any more in networks.


Star topologies are most commonly used due to it being simple and efficient. A centralized node whereas other nodes must communicate through it.


A tree topology is ideal when a device acts as a ROOT device on the network. It's a star and bus combined however multiple points of failure is a disadvantage of this type of topology


Hybrid topologies combine two or more topologies which can be flexible and scalable but very costly and complex to maintain.


Lastly, a mesh topology has all network nodes interconnected. Very redundant and availability is the most important however it is high cost and complex.


These topologies can be both logical and physical. You can have a physical diagram and a logical diagram to show both how they are connected and how signaling works in a network. A good example would be if you are using a bus topology to physically connect computers together but their signals are transmitted in a star topology.





Still in the conversation of how networks are classified, architecture is something we will end on. Architectures are the design of a network. Just like topologies and types but they refer to how the network components are functioning and how they are configured. There are two types of network architectures; Collapsed and three tiered.



A three tiered network architecture is typically used as a logical enterprise design. As you may have guessed, it has three layers of data connections. Starting from the bottom of the design, the first tier is used for user access whereas a computer connects to the network, it's called the Access Layer. The second tier labeled the distribution layer. This layer is used for routing traffic and filters out unwanted traffic. The last layer, which is the Core Layer, is to move traffic as fast as possible. Assuming all traffic is filtered, it sends the approved data to the enterprise network. The Core Layer is expected to have high reliability and availability.




The collapsed architecture is for smaller networks. It operates just like the three tier architecture but the core and the distribution layers are combined. In smaller, non enterprise networks, there is not a lot of traffic therefore the core and distribution can operate at the same layer.



As you learn more about networking, you will have a better understanding of how networks are categorized. You may not get the full picture right now but that’s okay. We will dig deeper and all of this will start to make sense and come full circle. As you continue in your learning, you will get that "aha!" moment.


Before we end on the topic on network basics, I want to go over the types of cables in a network.


There are two types of cables in networking; copper and fiber.

These cables help transfer data from one device to the next.



Copper cables transmitted data through electricity. The most commonly used copper cable is an ethernet cable. You can think of these cables as being used to connect your desktop computer to your modem or for your modem to connect to the jack on your wall. Within copper cables, there are sub categories. These categories separate the different types of copper cables. There are three types of copper cables; straight through, crossover and rollover. They are classified by the wires inside of the cables




Straight through copper cables have wires that match at each end. If you look at the end of an ethernet cable, you will see multiple colors. And if you look closely at both ends together, you will see that the order of the colors are the same. This means that the wires are straight throughout the cable classifying it as a straight through copper cable.




Crossover cables have wires that are crossed. Again, looking at both ends of an ethernet cable, you will see the colors do not match up. That's because the wires are "crossed" with each other, hence the name, crossover cable.




Rollover copper cables are the exact opposite of straight through cables. The wires inside the cable are rolled in the middle making each side opposite. For example, if red is the first wire on one end, the other end will have red as the last wire. The wires from one side is just flipped or rolled so the other side becomes its opposite. They are not crossed with each other like a cross over cable.


With copper cables, we now know the three types. With those three types, the cables can be either shielded twisted pair (STP) or unshielded twisted pair (UTP). STP cables basically means that there is a shield around the wires. This shield is a metallic foil that reduces electromagnetic interference (EMI). UTP cables do not have metallic foil wrapped around its wires thus it is cheaper and easier to manage than STP cables.


Moving forward, let's talk about fiber cables. Fiber cables also known as fiber optic cables, transmit data through light. It is made up of glass and plastic fibers that house light. There are two types of fiber cables; single-mode and multi-mode.




Single mode is whereas a single strand of glass fiber that supports one mode of transmission. It can run for very long distances and is expensive compared to multi-mode. Multi-Mode supports multiple modes of transmission and is used to smaller distances than single-mode fiber optics.


When choosing the right cable for the job, you have to know the specifics and what type of connection is required. If you're wiring an apartment complex for internet connection, fiber optic cables are what you would use but if you are trying to connect your desktop computer to the router in your home, copper may be the best choice.


Either way, knowing the basics of cables gives you a solid understanding of how data is transmitted and which ones should be in your environment.

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