A computing system is made up of one or more computing devices that work together to solve a problem or provide a service. A network is a common type of computing system that links two or more computers to share data. Networks are built with a mix of computer hardware and software. In this lesson, you are going to learn about the basic pieces of hardware that are used to build computer networks.

Question

Network Connections
A network can create a path between two computing devices on a computer network (a sender and a receiver). This path is a sequence of directly connected computing devices that begins at the sender and ends at the receiver. The process of finding these paths between computing devices is called routing.

In order to create these paths on a network, each computer needs at least one network adapter. A network adapter is a device that knows how to send and receive data across a network connection.

Wired Adapters
Wired Network AdapterComputers that are connected with physical wires will have a network adapter that contains a connection socket. A network cable will plug into that socket to connect the computer to the rest of the network. All of the data transferred to and from your computer over the network will flow through that network adapter and connected cable.

Many computer motherboards today have built-in network adapters, but you can also buy a separate network adapter card to add to your desktop computer. Ethernet cards are the standard network adapters used on most desktop computers.

Wireless Adapters
Wireless Network AdapterSome computers, especially laptops and mobile devices, will connect to other computers using a wireless network. A wireless network adapter (or Wi-Fi adapter or Wi-Fi hotspot) does not have any physical connection to an Ethernet wire. The adapter may plug into a device to provide an antenna or it may be hidden entirely within the device. The wireless adapter is responsible for sending and receiving data using over-the-air signals instead of physical wires.

Today, many local networks within homes and businesses are built using wireless connections. It is much easier to set up a wireless network instead of routing physical wires through the walls to every location and desk that needs a connection.

However, there are some drawbacks to using a wireless network. Wireless networks can be slower than a wired connection. You also need to configure extra security on a wireless network to avoid having a nearby device that belongs to someone else join your network, steal your data, or spy on your online activity. The range of a Wi-Fi adapter is limited, so if your mobile device leaves the building or moves too far away, it will lose the network connection.

Cellular Data Networks
Mobile devices like smartphones or newer cars also want to have network connections. But, they can move well beyond the range of a Wi-Fi adapter in your home or business. Instead, these mobile devices can get network access through a cellular connection to local cell phone towers. These connections may be slower and more expensive than the dedicated wired or wireless adapters in your home, but it's very convenient to be always connected to the Internet as long as you are within range of a cell tower.

Network Bandwidth
The term bandwidth refers to the amount of data you can push through a network connection over a given time. This bandwidth is typically measured in bits per second. Usually, your wired networks will have the highest bandwidth, meaning they are the fastest data connection to the Internet. Some types of network cables have better speeds than others, but as a group they all tend to be faster than any wireless options.

If you have a wireless access point or Wi-Fi adapter, you can also get pretty good bandwidth for the mobile devices in your home or office. You might not get the same speed as a wired connection, but you can still surf the web, stream movies and play games without noticing much difference.

The cellular data networks will have the slowest speeds relative to wired networks or Wi-Fi hotspots. Your mobile device usually has limited power and needs to communicate over long distances to a cell tower, so the data bandwidth is overall slower than other options in your home or business. But again these connections are often good enough to watch movies, and wireless technology improves every year.

Network Cables
Over time, several different kinds of network cables have been created to physically connect computers together.

Coaxial Cables

coaxial cableThe first type of cable that was used in networks is called coaxial or "coax" cable (pronounced "co-axe"). These cables have an inner copper wire surrounded by insulation and other shielding. Today we often use coax cables to connect our televisions to antennas and cable boxes. But in the 1980s and early 1990s, coax was used to build computer networks too! However, coax cables are not very flexible and can be hard to install throughout a home or business.

Twisted Pair Cables

twisted-pair cableIn the 1990s, a new standard for network cables emerged: the "twisted pair" cable. Twisted pair cables contain up to 8 wires, wound together in pairs to minimize electromagnetic interference.

Ethernet cableTwisted pair cables became the standard Ethernet cables that we still use today to connect our personal computers to home and business networks. Ethernet cables are separated into categories that can support different network speeds.

The "Category 3" Ethernet cable was an early favorite, capable of transferring data at speeds up to 10 Mbps (megabits per second, or million bits per second). The "Category 5" Ethernet cables can transfer data at speeds up to 100 Mbps. The current favorite, "Category 5e" can handle up to 1 Gbps (gigabits per second, or billion bits per second), and even higher standards do exist.

Fiber-Optic Cables

Fiber optic cableThe latest innovation in network cables is called fiber optic cable. Instead of using insulated metal wires to transfer data, fiber optic network cables use tiny strands of glass and sends data with pulses of light. You might think that a cable made of glass would be very difficult to work with, but in reality, since the strands of glass are so thin, the cable is very small and flexible.

Fiber-optic cables were initially used to connect together networks that were far apart or that needed to move a high volume of data. However, Internet Service Providers continue to build faster networks that can manage more data. Part of that effort includes rolling out fiber-optic service all the way to individual homes! Your neighborhood may already have fiber-optic service, enabling very fast Internet connections.

Baseband and Broadband Data
There are different ways to send data along network cables. Two of the most common ways are called baseband and broadband. In a baseband channel, data is sent using digital signals that take up the entire bandwidth (or capability) of the cable. Baseband channels are bi-directional, which means the same wire can be used to send and receive data signals. Ethernet-based Local Area Networks (LANs) are one example where baseband channels are used.

Broadband sends information in the form of an analog signal. Each data signal is assigned to a certain frequency, and you can layer more than one data stream on a channel at the same time using different frequencies. However, broadband communication is unidirectional, which means one channel can only be used to send or receive. For two-way communication, two channels are needed. You can make two channels by assigning separate frequencies for sending and receiving along the same cable. Or, you can just use two cables, one for sending and one for receiving. Broadband has historically been used to carry signals for telephone and cable TV networks.

Network Devices
In most cases, computers are not connected directly to each other. Instead, they join larger groups of computers on a network. The backbone of the network is formed with a variety of network devices that know how to route data between computers.

Hubs

Network hub imageA network hub is a central device that contains many different ports (sockets). Ethernet cables will join together several computer network adapters to the hub. The hub is a simple device that has no idea what devices are connected to it.

When data is sent from one computer through an Ethernet cable to a hub, the hub will repeat that information back to all of the computers connected to the hub. Each of these computers then need to check the data and see if it is the intended receiver, and ignore the data if it was meant for someone else.

Switches

A switch is similar to a hub, but it is a little bit smarter. The switch will understand exactly which computers are connected to it. Each computer is identified by a unique address. When the switch receives a data packet, it will examine the target address and send that information only to the target computer. A switch will not broadcast information to all the other computers in the network.

Routers

Hubs and switches are used to connect together small groups of computers in your home, classroom, or business. But how would you connect these small groups together to form larger networks? To do this, you will need a few more pieces of equipment, starting with a device called a router.

A router is a device designed to pass information between multiple networks. Routers are located at gateways, the places where two or more networks connect. These devices are more intelligent than either a network hub or switch. When data is received from the external network, the router will figure out where the data is coming from and the address of the target device. This information is then passed up to the correct hub or switch, which then passes the information to the target computer. Routers often contain features such as a firewall to block unwanted traffic, a filter to block access to unwanted websites and the ability to report on the data usage of connected devices.

Computer to Router to Internet image

Home network routers are often called broadband routers. These devices are designed to join a home network directly to the Internet. A modem, which is used to understand the particular type of network signal sent by an Internet Service Provider, is often included in a home router.

Wireless Access Points
Wireless network imageA router in a home or business may also contain a Wireless Access Point (WAP). The WAP acts as a hub or switch for all of the wireless devices connected to the network.

In a home network, it’s common for the WAP to come as part of the router. So this one router box can handle all of your wired Ethernet connections, all of your wireless mobile devices, and communicate to the Internet Service Provider through a built-in modem.

1. What is the purpose of a network adapter?
2. What is the difference between a wired and wireless adapter?
3. What are some advantages and disadvantages of a wireless network?
4. How do the bandwidths of wired, wireless, and cellular connections compare?
5. What are the three main types of network cables?
6. Which network cable joins together most wired computers in today's local networks?
7. Which network cable is used to connect high-data or remote networks and is slowly being rolled out to home locations?
8. What is the difference between broadband and baseband channels?
9. What components are used to join together several computers in a local network?
10. What is the difference between a hub and a switch?
11. What extra features does a router have to join networks together?
12. What does a Wireless Access Point (WAP) do?

Answer 1

1. The purpose of a network adapter is to send and receive data across a network connection.
2. A wired adapter connects to a network through physical wires, while a wireless adapter connects through over-the-air signals without the need for physical connections.
3. Advantages of a wireless network include the ease of setup, no need for physical wiring, and the ability to connect devices without being in close proximity to the router. However, disadvantages include potential security risks, limited range, and slower speeds compared to wired networks.
4. Wired connections generally have the highest bandwidth, followed by wireless connections. Cellular connections typically have the slowest speeds.
5. The three main types of network cables are coaxial cables, twisted pair cables (such as Ethernet cables), and fiber-optic cables.
6. Ethernet cables, specifically Category 5e or higher, are the most commonly used cables to connect wired computers in local networks.
7. Fiber-optic cables are used to connect high-data or remote networks and are slowly being rolled out to home locations.
8. Baseband channels send data using digital signals that take up the entire bandwidth of the cable, allowing for bi-directional communication. Broadband channels send information in the form of an analog signal and can carry multiple data streams at the same time, but are unidirectional.
9. Hubs, switches, and routers are used to join together several computers in a local network.
10. A hub repeats incoming data to all connected computers, while a switch understands the connected devices and sends data only to the target computer.
11. A router has the ability to pass information between multiple networks and may include features such as a firewall, filter, and the ability to report on data usage.
12. A Wireless Access Point (WAP) acts as a hub or switch for wireless devices connected to the network, allowing them to access the network and communicate with other devices.