What is a Computer Network? – Types & Definition – Video & Lesson Transcript | Study.com

Ethernet

Ethernet is the technology that is used to connect devices to a network (local or wide-area). Ethernet is a description for how these devices can talk to one another. Your everyday interaction is most likely via an Ethernet cable, the cable plugged into your router.

Types of Network Connections

Computer networks can be broken down historically into topologies, which is a technique of connecting computers. The most common topology today is a star topology.

Star Topology

A star topology is a design of a network where a central node extends a cable (or wireless) to each computer on the network. On a star network, computers are connected independently to the center of the network.

A star topology allows straightforward management of the entire network from one place. Since each node has its own connection, the loss of one node won’t break the whole thing. If you need to add a device to the network, it plugs right in, without additional extra effort.

The only problem is that there is a single point of failure in the star network. If there’s only one hub, the whole thing goes down. However, networking professionals will often have fail-over servers–backups–that keep things running while they fix the main server.

Bus Topology

A bus topology is another type of design where a single cable connects all computers and the information intended for the last node on the network must run through each connected computer. If a cable is broken, all computers connected down the line cannot reach the network. The benefit of a bus topology is a minimal use of cabling.

Ring Topology

A similar topology is called a ring. In this design, computers are connected via a single cable, but the end nodes also are connected to each other. In this design, the signal circulates through the network until it finds the intended recipient. If a network node is not configured properly, or it is down temporarily for another reason, the signal will make a number of attempts to find its destination.

A collapsed ring is a topology where the central node is a network device called a hub, a router, or a switch. This device runs a ring topology internally and features plugins for cables. Next, each computer has an independent cable, which plugs into the device. In offices that have the collapsed ring, there will be a cabling closet, or a space containing a switch device that connects the network. All computers in the office connect to the cabling closet and the switch. Even if a network plug is near a desk, the plug is connected via a cable to the cabling closet.

With the increase of wireless technology, many nodes on the network will connect to a wireless access point. This then connects to the main server(s)–the hubs–of a star network.

Cable Types

Cables are conductive media that allow the signal to flow. The signal can be an electric pulse or a light flicker. The type of signal carried through the cable is defined by the material the cable is made out of. All cables have a limitation as to how far they can carry a signal without a natural process of signal loss called attenuation.

Coaxial cable, often used for cable television, features a central copper wire and many layers of insulation. The cable can carry the Internet connectivity along with other information.

The most common type of a cable is a twisted copper cable made of copper wires twisted together (the Ethernet cable). The cable traditionally used for telephone connections is a pair of copper wires in a plastic insulation. Other cables contain five or seven wires and vary in the amount of twist applied to the wires. When the wires are twisted, they can withstand higher levels of noise and carry the signal more efficiently. The end of the cable usually features a plug. Each copper wire has its own touch point, enabling the user to simply plug in a cable and make it portable.

Another type of a cable is a fiber optic cable with a core of a strand of glass that carries light. This helps to carry the signal a longer distance without the need to repeat it. The new efficiency allows the carrying of more information in a single cable, which has the result of making the network faster for a single end user. The signal itself continues to flow in the copper wire and in the fiber-optic cable at the same speed, near the speed of light.

Fiber is gaining ground rapidly on coaxial cable. You may even have companies installing fiber optic cables right to your home (competing with the traditional cable companies). This fiber optic setup promises much higher bandwidth and greater network speeds over cable.

Lesson Summary

A computer network is a set of computers, or nodes, that are connected by cables or connect wirelessly via radio waves. There are several techniques that may be used to establish the network. The most common today is the star topology. Other techniques, or topologies, are called ring (including collapsed ring), and bus. Cabled connections may utilize coaxial cables, fiber optic cables, or most commonly, twisted copper cables. A network of computers can share information and resources, which allows them to do more than a single computer.

Learning Outcomes

Once you are finished, you should be able to:

• Describe a computer network and define nodes
• Provide examples of resources that a network may share
• Identify the types of topologies used to connect the nodes on a network and explain the benefits and challenges of each
• Name and discuss the types of cables used for a computer network
• Recall the most common type of topology and cable used today