What is a computer network?

Lesson

Networks are made up of network nodes (endpoints, switches and routers) which use interconnections to communicate with each other and move data from one device to another. Network components may be structured in a number of different topologies depending on the size and purpose of the network. For example a home network will look very different to an enterprise network which could span multiple offices across the globe.

To make it easier to build networks using many components, potentially from many different manufacturers we split it into layers. The lowest layer includes the medium used to transmit ones and zeros across physical space – for example an Ethernet cable or some form of wireless technology. The highest layer includes applications such as a web browser which turns the data transmitted across the network into something useful. We use two models to represent networks, the Open Systems Interconnection (OSI) model and the TCP/IP or Internet Protocol Suite model.

Each layer will implement one or more protocols as a means of communication. A protocol is simply a set of rules which all parties follow in order to understand each other. For example, let's look at a protocol analogy for social etiquette:

Party A initiates communication with “Hello”
Party B acknowledges this with “Oh, Hello”
Party A asks “How are you?”
Party B replies “Good thank you.”
Party B reciprocates “How are you?”
Party A replies “Good too, thank you.”

Free flow conversation is now free to happen until either party decides to close the conversation:

Party B initiates the close of the conversation with “Well, must be off. Bye!”
Party A hears the “Bye” and reciprocates, thus closing the conversation. “Bye!”

Devices on a network, like the people in our analogy, will only communicate successfully if they both adhere to the same protocol.

The core protocols in use today, including the Transmission Control Protocol (TCP) and the Internet Protocol (IP), date back to research carried out for the US Department of Defence and at US universities in the 1970s and 1980s.

Questions

Test your knowledge with these questions.

LAN stands for Local Area Network. A LAN connects devices in a relatively small physical area such as a room or building.

WAN stands for Wide Area Network. A WAN connects devices over long distances.

In computer networking, a protocol is a set of rules which define the language devices use to communicate with each other.

Two commonly used models in computer networking are the OSI 7 Layer Reference Model and the TCP/IP model.

Local Area Network

Local Area Network (LAN)

Wide Area Network (WAN)

Wide Area Network

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Summary of the TCP/IP Model

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This lesson is part of the following courses.

Computer Networking Foundations

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What is a computer network?

Questions

Define LAN

Define WAN

What is a network protocol?

Give two examples of models used to represent computer networks.

What does LAN stand for? 1. Local Area Network 2. Local Area Node 3. Language Agnostic Network 4. Local Access Network

Which term would best describe a group of connected devices which are all within the same building. 1. Wide Area Network (WAN) 2. Open Systems Interconnected Network (OSI) 3. WiFi 4. Local Area Network (LAN)

Which term best describes a network which connects devices in multiple offices located across the globe? 1. Local Area Network (LAN) 2. Large Area Network (LAN) 3. Wide Area Network (WAN) 4. Wireless Local Area Network (WLAN)

What does WAN stand for? 1. Wireless Activity Node 2. Wireless Area Network 3. Wide Area Network 4. World Area Network

Other Lessons

Summary of the TCP/IP Model

Courses

Computer Networking Foundations