A computer network is a set of devices/nodes connected by communication links. And the node can be a computer, printer or any other device that can send or receive data generated by other nodes. Computer network is required for data communication which is necessary in today’s business. A network should have more throughput, high reliability and data security.

Any network can be laid out physically in four different ways. They are as follows:

a) Mesh topology
b) Star topology
c) Bus topology
d) Ring topology

Mesh topology: In this network every device has a dedicated point to point link to every other device. So, for a network with n nodes, we need n (n-1) / 2 links. It eliminates the traffic problem because each connection carries its own data load. Also offers advantages of security and easy fault identification. Failure of one link does not affect the whole network.

Its main disadvantages are amount of cabling required and the expensive hardware to connect each link. So, it has very limited implementation.

Star topology: In this case, each device has a dedicated point to point link to a central hub and the hub acts as an exchange. Here the devices are not directly connected to one another. It is less expensive compare to mesh topology. Also requires less cabling and easy to install.

The major problem occurs when the hub goes down, then the whole system is dead. It is generally used in local area networks (LAN).

Bus topology: It is a multipoint connection where one long cable acts as a backbone to link all other devices. Nodes are connected to the main cable by drop lines and taps. Its advantages are easy installation and less cabling requirement.

Its disadvantages are difficulty in fault isolation, signal quality degradation as it travels farther and farther. A fault in the bus cable can stop all the transmission in the network. Generally, Ethernet LAN uses this topology.

Ring topology: In a ring topology, each device has a dedicated point to point connection with other two nodes on its either side. It is easy to install and reconfigure a ring. But a break in the ring can disable the entire network. It was earlier used when IBM introduced its local area network.

Categories of Networks:

A network can be categorized based on its size. There are three types of networks as follows:
1) LAN
2) WAN
3) MAN

LAN (Local Area Network) – it is the network limited within a single office, building or campus and its size is limited to a few kilometers. LANs are used to allow sharing of resources (data, printer, application program etc.) between PCs. LAN topologies can be bus, ring or star. It has data transmission speed between 100-1000 Mbps. Wireless LAN is the latest LAN technology.

WAN (Wide Area Network) – It provides long distance transmission of data over large geographic areas that may comprise a country, a continent or the whole world. Switched WAN is used for connecting end systems (routers) that connects to another LAN or WAN. X.25 and ATM (asynchronous transfer mode) network are example of switched WAN. Wireless WAN is also becoming more popular recently.

MAN (Metropolitan Area Network) – It is limited inside a town or a city. Its size is in between a LAN and a WAN. It is used in cable TV network and for high speed internet connection.

Internet: It is a collection of thousands of interconnected networks. It is made up of many wide-area networks and local-area networks joined by connecting devices. 

Bluetooth: it is a wireless LAN technology that connects devices in a very small area. It can connect telephones, laptops, desktops, cameras, printers, coffee makers etc. A Bluetooth LAN is called a piconet. And multiple piconets form a network called scatternet.

Virtual LAN: It is a local area network configured by software, not by physical wiring. VLAN group stations belonging to one or more physical LANs converted into broadcast domains. It reduces network traffic and provides an extra measure of security. Also It is cost and time efficient.

In the next article I am going to describe The OSI model in details…


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