A network is a group of computer systems connected together. We can have many types of computer networks:
- local area network (LAN) – in this type of network all the devices interconnected are geographically close one to another (same room, same building).
- metropolitan area network (MAN) – a network which is designed to connect certain devices spread in an entire town/city.
- wide area network (WAN) – in this type of network computers can be located on different parts of the world and are connected together by telephonic lines or radio waves. In this network category goes the Internet.
These three network types are the most popular and more frequently used. There are also other types less known as CAN (Campus Area Network – here the devices are located in a limited area such as military base or a university campus), or HAN (Home Area Network – network which connects a person’s digital devices used at home).
In additional to all these types, there are some characteristic which are used to categorize the different networks:
- topology: the way how the devices are geographically arranged. Common topologies of include a bus, star and ring.
- protocol: is a set of rules which governs over the network data communication. The most common protocol for LANs is called Ethernet .
- architecture: networks can be classified as using a peer-to-peer or a clisnt/server architecture.
In a network computers are usually called nodes. Computers and all devices that allocate resources for the other network devices are called servers.
The word topology refers to the shape of a network, commonly called network layout. The network topology determines how different nodes are connected to each other and how they communicate. Topologies can be physical or logical. In the below diagrams you will find the five most common network topologies:
A mesh topology provides redundant communication paths between some or all devices. This means that every node has a connection to every other node in the network.
All devices are connected to a central device (switch). All nodes communicate across the network by passing data through the switch which sends the data to the destination node.
All devices are connected to a central cable. This cable is more commonly called BUS or Backbone.
All devices are connected to one another in the shape of a closed loop (ring). In this situation each device is connected directly to two other devices (neighbor).
Alternatively referred to as a star bus topology, tree topology is one of the most common network setups that is similar
to a bus topology and a star topology. A tree topology connects multiple star networks to other star networks.