Computer Network can be defined as a set or collection of computing devices that are linked to each other in order to communicate and share their resources with each other. A computer Network is a mixture of hardware and software devices.
Computer networks finds its application in various fields:
* Home Applications: Nowadays most of the people buy computers for home not for games or movies but for internet.Some of the popular uses of the Internet for home users are as follows:
1. Access to remote information.
2. Person-to-person communication.
3. Interactive entertainment.
4. Electronic commerce. As internet is a network, so using this network, people can communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.
* Business Applications:
The most important business application of computer networks is file sharing hardware, files, data and other resources.In a networked environment, each computer on a network may access and use hardware resources on the network, such as printing a document on a shared network printer.
The capability of providing access to data and information on shared storage devices is an important feature of many networks. Users connected to a network may run application programs on remote computers.
Types of Networks:
Networks on the basis of their scale, scope and purpose,can be categorized as Local area network (LAN), wide area network (WAN), Metropolitan area network (MAN), Personal area network(PAN), Virtual private network (VPN), Campus area network (CAN), Enterprise Private Network, Storage area network (SAN) and others
Local Area Networks:
A LAN is a type of computer Network in which networking facility is available in a small physical area (mostly in meters but very rarely in kilometers) probably in an office building,home,school or places like airport,hostel etc. Each Computer or device connected to the network is called a node.A LAN is useful for sharing resources like files, printers, games or other applications. The most common type of local area network is an Ethernet LAN.
Wide Area Networks:
A wide area network (WAN) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries).A WAN covers a larger areaby using communication channel s that include numerous telephone lines,cables etc.
Metropolitan Area Network (MAN):
It is a type of network that covers an area larger than a LAN but smaller than a WAN e.g a city.The best-known example of a MAN is the cable television network available in many cities.
Personal Area Network (PAN):
A personal area network (PAN) is a small computer network used for communication among computer and other communicating and information giving devices. PAN can be personal computers, printers, fax machines, telephones,
A campus network is a computer network covering an area of several LANS but smaller than a MAN.A CAN may cover a college,university and areas like hostels.
Enterprise Private Network
An enterprise private network is a network build by an enterprise to interconnect various company sites, e.g., production sites, head offices, remote offices, shops, in order to share computer resources.
Storage Area Network:
Storage Area Networks connects servers to data storage devices
Home Area Network:
A home area network (HAN) also referred as Office area network(OAN) is small home LAN used for communication between digital devices present in home.These devices can be limited number of personal computers and devices like printers and mobile computing devices.
Virtual Private Network:
In a large network,when the links or connection between nodes are established through virtual circuits instead of using physical medium(i.e some cables or wires etc) ,the network is said to be virtual private network.Generally, a VPN has a topology more complex than point-to-point. Network Topologies: Various Network topologies are possible for broadcast LAN.It may be a bus,ring or Star topology.The figure below shows various topologies.
In Bus topology, all of the computers share and communicate across one common conduit, whereas in a star network, all data flows through one centralized device.
Computer Networks exist in different design. Two of the most important are:
1. Client/Server Architecture.
2. Peer to Peer .
In a client-server architecture, all files are stored on a centralized,high speed file server PC that is made available to clients.This high speed Server is also responsible for managing other resources as well..Clients behave as workstations without sharing any resources.. Examples of client-server systems are Web browsers and Web servers, FTP clients and servers, and DNS.
Peer To Peer Network: Unlike client-server networks, , the information stored across peer-to-peer networks is uniquely decentralized.Here each computer acts as a client as well as a server. This peer-to-peer networks are much more common in homes.
NETWORK PROTOCOLS :
A Set of rules and conventions that provide error-free and maximally convenient information transfers are called network protocols. In simple words, the communication language used by computer devices is called network protocol. Protocols define connectors, cables, signals, data formats, error control techniques, and algorithms for message preparation, analysis transfer, with send and delivery. Multiple protocols are implemented by networks to support specific applications. Popular protocols include TCP/IP, the most common protocol found on the Internet and in home networks.
Comparison Of Human and Computer Network Protocol :
The client-server model can be used on the Internet as well as local area networks (LANs). Examples of client-server systems on the Internet include Web browsers and Web servers, FTP clients and servers, and DNS.
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