Computer Network

A computer network is a set of computers connected together for the purpose of sharing resources, data, and applications. The most common resource shared today is connection to the Internet. Other shared resources can include a printer or a file server. The Internet itself can be considered a computer network.

A computer network can be categorized by their size. A computer network is mainly of four types;

LAN(Local Area Network)
PAN(Personal Area Network)
MAN(Metropolitan Area Network)
WAN(Wide Area Network)

What is LAN?

A Local Area Network (LAN) is a group of computer and peripheral devices which are connected in a limited area such as school, laboratory, home, and office building. It is a widely useful network for sharing resources like files, printers, games, and other application. The simplest type of LAN network is to connect computers and a printer in someone's home or office. In general, LAN will be used as one type of transmission medium.
It is a network which consists of less than 5000 interconnected devices across several buildings.

Characteristics of LAN

It is a private network, so an outside regulatory body never controls it.
LAN operates at a relatively higher speed compared to other WAN systems.

Advantages of LAN

Computer resources like hard-disks, DVD-ROM, and printers can share local area networks. This significantly reduces the cost of hardware purchases.
You can use the same software over the network instead of purchasing the licensed software for each client in the network.
Data of all network users can be stored on a single hard disk of the server computer.
You can easily transfer data and messages over networked computers.
It will be easy to manage data at only one place, which makes data more secure.
Local Area Network offers the facility to share a single internet connection among all the LAN users.

Disadvantages of LAN

LAN will indeed save cost because of shared computer resources, but the initial cost of installing Local Area Networks is quite high.
The LAN admin can check personal data files of every LAN user, so it does not offer good privacy.
Unauthorized users can access critical data of an organization in case LAN admin is not able to secure centralized data repository.
Local Area Network requires a constant LAN administration as there are issues related to software setup and hardware failures

What is PAN (Personal Area Network)?

PAN is a computer network formed around a person. It generally consists of a computer, mobile, or personal digital assistant. PAN can be used for establishing communication among these personal devices for connecting to a digital network and the internet.

Characteristics of PAN

It is mostly personal devices network equipped within a limited area.
Allows you to handle the interconnection of IT devices at the surrounding of a single user.
PAN includes mobile devices, tablet, and laptop.
It can be wirelessly connected to the internet called WPAN.
Appliances use for PAN: cordless mice, keyboards, and Bluetooth systems.

Advantages of PAN

PAN networks are relatively secure and safe
It offers only short-range solution up to ten meters
Strictly restricted to a small area

Disadvantages of PAN

It may establish a bad connection to other networks at the same radio bands. Distance limits.

What is WAN?

WAN (Wide Area Network) is another important computer network that which is spread across a large geographical area. WAN network system could be a connection of a LAN which connects with other LAN's using telephone lines and radio waves. It is mostly limited to an enterprise or an organization.

Characteristics of WAN

The software files will be shared among all the users; therefore, all can access to the latest files.
Any organization can form its global integrated network using WAN.

Advantages of WAN

WAN helps you to cover a larger geographical area. Therefore business offices situated at longer distances can easily communicate.
Contains devices like mobile phones, laptop, tablet, computers, gaming consoles, etc.
WLAN connections work using radio transmitters and receivers built into client devices.

Disadvantage of WAN

The initial setup cost of investment is very high.
It is difficult to maintain the WAN network. You need skilled technicians and network administrators.
There are more errors and issues because of the wide coverage and the use of different technologies.
It requires more time to resolve issues because of the involvement of multiple wired and wireless technologies.
Offers lower security compared to other types of networks.

What is MAN?

A Metropolitan Area Network or MAN is consisting of a computer network across an entire city, college campus, or a small region. This type of network is large than a LAN, which is mostly limited to a single building or site. Depending upon the type of configuration, this type of network allows you to cover an area from several miles to tens of miles.

Characteristics of MAN

It mostly covers towns and cities in a maximum 50 km range
Mostly used medium is optical fibers, cables
Data rates adequate for distributed computing applications.

Advantages of MAN

It offers fast communication using high-speed carriers, like fiber optic cables.
It provides excellent support for an extensive size network and greater access to WANs.
The dual bus in MAN network provides support to transmit data in both directions concurrently.
A MAN network mostly includes some areas of a city or an entire city.

Disadvantages of MAN

You need more cable to establish MAN connection from one place to another.
In MAN network it is tough to make the system secure from hackers

Computer networking is a set computing devices (or Computers) connected together for the purpose of sharing information between two or more computing devices. Computers (or Computing devices) on the network are called nodes, the connection between two or more computers can be done vai Wired Connection and wireless Connection.

A Wired Connection involves making use of cables to aid communication between the computers. The cables can be coaxial, Fibre optic etc.

A Wireless Connection involves using the air as the medium for communication. Technologies like Bluetooth, wifi etc are wireless communication technologies.

There are some techniques of connecting computers called topologies.

Star Topology
Bus Topology
Ring Topology

Star Topology: Star topology is a technique to design a network where central node extends the cable to each node (or Computer) on the network. In this technique computers are connected independently to the center of the network.

Bus Topology: 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.

Ring Topology: 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.

Key Networking Terms

Open system: an open system is connected to the network and prepared for communication.

Closed system: a closed system is not connected to the network and so can't be communicated with.

IP (internet protocol) address: the network address of the system across the network, which is also known as the Logical Address).

MAC address: the MAC address or physical address uniquely identifies each host. It is associated with the Network Interface Card (NIC).

Port: a port is a channel through which data is sent and received.

Nodes: nodes is a term used to refer to any computing devices such as computers that send and receive network packets across the network.

Network packets: the data that is sent to and from the nodes in a network.

Routers: routers are pieces of hardware that manage router packets. They determine which node the information came from and where to send it to. A router has a routing protocol which defines how it communicates with other routers.

Network address translation (NAT): a technique that routers use to provide internet service to more devices using fewer public IPs. A router has a public IP address but devices connected to it are assigned private IPs that others outside of the network can't see.

Dynamic host configuration protocol (DHCP): assigns dynamic IP addresses to hosts and is maintained by the internet service provider.

Internet service providers (ISP): companies that provide everyone with their internet connection, both to individuals and to businesses and other organizations.

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