|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. Networks on the basis of their scale, scope and purpose,can be categorized as:Local area network (LAN)
Each one is explained in detail as follows:
1. 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 distinguishing characters of LAN which separates it from other types of networks are:
- Size of the LAN
- Transmission technology used by LAN and
- Network topology
LAN are restricted in size and due to this simplifies network management. LAN probably use a transmission technology consisting of inexpensive hardware such as Ethernet cables, to which all other devices or computers are attached. Speed of LAN ranges from 10 Mbps to 100 Mbps and thus has an advantage of having low delay of microseconds or nanoseconds.
Examples of LAN:
The most common type of local area network is an Ethernet LAN. The smallest home LAN has exactly two computers whereas a large LAN can consist of thousands of computers. Many LANs are divided into logical groups called subnet. Various Network topologies are possible for broadcasting 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.
2. 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 area by using communication channel s that include numerous telephone lines,cables etc. A WAN can be thought of as a geographically-dispersed collection of LANs. LANS are connected to WAN through a network device called a router. The Internet is the largest WAN covering the Earth. WANs tend to use technology like ATM, Frame Relay and X.25 for connectivity over the longer distances.
3. 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.
4. Personal Area Network (PAN):
A personal area network (PAN) is a computer network used for communication among computer and other communicating and information giving devices.Some examples of devices used in a PAN are personal computers, printers, fax machines, telephones, PDAs, scanners, and even video game consoles. A PAN may include wired and wireless connections between devices.
5. 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.
6. Campus Network:
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.
7. 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.
8. 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. A Home Area Network probably employs one LAN and internet access is taken with the help of an Internet Service Provider. This sharing of Internet is an important property of HAN. Many devices are capable of being networked. Some of the more obvious categories (with examples) are as follows:
- Computers (desktop PC, notebook PC, PDA, shared peripherals)
- Entertainment (TV, DVD, VCR, camcorder, camera, stereo, MP3)
- Telecommunications (telephone, mobile telephone, intercom, fax)
- Appliances (microwave, refrigerator, clock, furnace, airco, lights).
- Telemetry (utility meter, smoke/burglar alarm, thermostat, babycam).
9. Storage Area Network:
Storage Area Networks connects servers to data storage devices
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