Computer Science: Types and Components of Computer Network
Edited by TheGuyLoveNY, Jen Moreau
Computer Network's Definition:
A computer network can be defined as a collection of interconnected computers in such a way that they share resources. A computer system only referred to a group of the computers and hardware components interconnected by communicating channels that allow sharing of resources and information. Technically, If at least one process in one computer can send or receive data to/from at least one process residing on a remote computer, then two machines are said to be a network.
As you can see from the diagram above, Any computer that engages with another computer by Sending/Receiving messages is supposed to be in a network. A system classifies according to a wide variety of characteristics such as, "Medium used to transport data," "Communication protocols used," "Scale,"Topology" and "Organizational scope."
Protocols are the Rules and data format for exchange of information between computers. And all the computers agree to follow this rules. One of the most important rules is
- OSI which stands from, Open System Interconnection.
- TCP/IP is another important protocol that computers use to exchange information between computers.
Components of a Computer Network:
Server: Server or Domain Controller is a powerful computer used in Domain network to manage and control all hardware and software, resources of a network. The server uses the server OS (Operating System), e.g., Win Server 2012. There are two types of Domain Controllers (Servers):
- PDC (Primary Domain Controller): A type of server that manages and controls the resources of a whole network. One domain network can have only one PDC.
- BDC( Backup Domain Controller): BDC is a server that keeps a complete backup of PDC. In the case of failure of PDC the BDC act as PDC. A network can have more than one BDC's according to requirement.
- Client: A type of computer in a network that can request for resources to the server. There are two types of clients.
- 1This kind of client can only process data, They don't have the ability to store the data.Intelligent Client:Advertisement
- 2These types of consumer benefit from both, They can process as well as store the data.Smart Client:
- Peer: Peer is a type of computer in a workgroup network that can act as a server as well as a client at the same time. Meaning, A peer can request and process a request simultaneously. Hence, It can act as both client and server.
- Media: Network Media or medium is the path through which data travels on a network. There are two main types of media:
- 1The media that has physical existence is called guided media or bounded media. Guided media consists of the following types of cables: Coaxial cable, Twisted pair cable, and Fiber Optic cable.Guided Media:
- 2A type of media which has no physical existence (Wireless) as a guided media. Some of the examples of Non-guided media are Radio Waves, Microwaves, Infrared waves.Non Guided Media:
- Connecting Devices:
These devices are used to connect a network media together. They act as a middleware between two computers or networks. The network contains the following connecting devices:
History of Network:
In September 1940, George Stibits used a teletype machine to send instructions for a problem, from his Model at Dartmouth College to his complex number calculators in New York and received results back by the same means. Linking output systems like teletypewriters to a computer was an interest at Advanced Research Project Agency (ARPA) when in 1962, J.C.R Licklide was hired and developed a working group he called the "Inter_galatic Network" a precursor to ARPANET.
Early networks of communicating computers include military radar system, Semi Automatic Ground Environment (SAGE), started in the 1950s. In the 1960s, the commercial airline reservation system semi-automatic business research environment (SABRE) went online with two connected mainframes in 1960s. In 1964, Researchers at Dartmouth developed the Dartmouth Time Sharing System for distributed users of Large Computer Systems.
In 1965, Thomas Marill and Lawrence G. Roberts created the first wide area Network (WAN). The first telephone switch used computer control was invented by Western Electric in 1965. In 1969, The University of California at Los Angeles, the Stanford Research Institute and the University of Utah were connected using 50 kbit/sec circuits.
Today, Computer Networks, are the core of modern communication. Computers control all public switch telephone network (PSTN), follows the Internet Protocols.
Types of Computer Network:
Personal Area Network (PAN): A personal area network (PAN), is a computer network used for communication among computer and different technological devices close to one or two people, usually at home. For example Computer, Printer, Scanner, Gaming Consoles, Cell phone, PDA.
Local Area Network (LAN): A local area network is a network in which two or more devices are connected locally. LAN covers short distance such as a building, Campus, a hotel, etc. Devices are connected either wirelessly or through a high-speed cable called Ethernet. This ethernet cable is a very high-speed cable with the speed of 100 MB/Sec. LAN has a slight chance of errors. LAN is highly reliable. The only drawback is it covers a small geographical area.
Home Network: A Home network is a very similar to LAN, but this LAN has a primary use for residentially. A Home network is used to connect devices in a home, such as a wireless printer that is attached to a computer and mobile device to print or scan wirelessly anywhere in the home. The source of sharing is through DSL (Digital Subscriber Line) provider. Usually, a smaller number of devices can be connected to this type of network.
Storage Area Network: Storage Area Network (SAN), Unlike other networks, this network allows a user to access and store data. SAN's are primarily used to make storage devices such as Disk arrays, and they are connected to the server giving an impression as if they are connected.
Campus Area Network: A Campus area network also known as Corporate area network is just an interconnection of multiple Local Area Network (LAN). A CAN or campus area network spans over a shorter distance than Wide Area Network (WAN) and Metropolitan Area Network (MAN).
Metropolitan Area Network (MAN) : A metropolitan area network spans over even larger area, Usually covers city, large campus, even states. Metropolitan Area Network(MAN) comparatively spans over a larger area than Local Area Network (LAN). On the other hand, This spanned area is but shorter when compared with Wide area network.
Wide Area Network (WAN): A wide area network (WAN) is spread over greater regions. WAN can be span over a city as big as Toronto; WAN can also span over a whole Country, as big as, Australia, It can span over even an intercontinental distance. Wide Area Network, as the name suggest, Is the most extensive network available.
Enterprise Area Network: Enterprise area network is used to interconnect various enterprise websites, for example, Head offices, remote offices, shops, etc in order to share resources. Enterprise area network act as a backbone for business communication.
Virtual Private Network: A Virtual private network act as a private network, It allows users to send/Receive information publicly as if they were directly connected to each other. VPN provide security over network to its users.
Internetwork: Internetwork uses gateways to connect computer networks having a common method of routing information between networks. The internet is an aggregation of many connected internetworks, spanning the earth.
- Intranet: Intranet is a set of networks, which is only available to organization's staff. It is a private network.
- Extranet: Extranet is a system that provides limited access to an authorized person, Without giving much of the organization's detail.
Internet: Internet is an agreement between millions of people using the network. They agree to connect to other network and share resources. It is successor of the ARPANET. Internet is also referred to connection of connection.
A network media acts like a path through which data flows on a network. Web media has two main types:
Guided Media: A network media that has physical existence guided media consists many types of cables. Following are the types of cables:
- Co-axial copper wire.
- Twisted Pair cable.
- Fiber Optic cable.
- Transatlantic cable.
Non Guided Media: Non guided media contains the following wireless media:
- Radio Waves.
- Microwaves such as Satellite waves, terrestrial waves.
- Infrared waves.
Physical layout of a network is called a network topology. A network topology refers to how computers are connected. There are following types of Network Topologies:
- Bus Topology.
- STAR Topology.
- Ring Topology.
- Mesh Topology.
BUS Topology is a type of network in which all computers are connected to the main trunk cable. All the computers are attached to the main trunk cable which is a coaxial copper cable called Thicknet. Thicknet links to PC through a thin cable called thinnet and BNC (Boynett Neilson Connector). A "T" Shaped connector. At both ends of a network, a device called terminator is attached.
Working: Whenever a PC generates a data packet. It is transmitted to thicknet. Here it is check by all terminals and kept by terminal it belongs. If data Segment does not belongs to any PC, it is ejected out by termination.
- Low-cost topology.
- Easy to configure.
- Reliable for small networks.
- A passive topology i.e when two or more terminals generate data at the same time it causes a data conflict.
- Low speed as 10 Mbps.
- No central control.
- Failure of one terminal may fail the whole network.
Ring topology is a type of network which is closed at both. In Ring Network each PC is provided two dedicated links of CAT 5 cable and RJ45 Connector. One clockwise other anticlockwise.
Whenever a Terminal generates data packet called the token. Token has two-way data flow Clockwise and Anticlockwise. The token is sent to a destination through lowest traffic area.
- High Speed 100 Mbps.
- Reliable for small networks.
- Easy to configure.
- Low cost.
- No Central control.
- Failure of One terminal may fail the whole network.
- Cannot exceed eight computers.
- Difficult to extend and troubleshoot.
Star topology is a type of network which is controlled by a Central controller device called the Hub or a Switch. Hub is a device that brings the web media together. Hub is of two types, i.e., Passive Hub, and Active hub. A Passive hub is a hub that receives signal noise and passes it to destination without any change; Hence it is known as a passive hub. Active Hub is a hub that receives a signals and noise boost up both of them then passes to a destination.
The smart hub receives signals, sound increase signals and discards noise, then passes signals to a target computer. These type of hubs are quick since they manage Routing, switching, bridging, etc. In the diagram below, We can see that each PC is connected to switch through CAT 5 cable and RJ 45 Connector. The switch can be attached to another switch also by using an uplink port.
Whenever a terminal generates data packet, It goes to switch. Switch boost up signals, discards noise then passes it to the destination computer. So basically, a sender computer sends a signal to the switch, which is then forwarded to the target computer.
- High speed 100 Mbps.
- Easy to configure.
- Easy to troubleshoot.
- Easy to extend.
- Reliable for both small and large network.
- Failure of one computer does not fail the system.
- Cost of a switch is additional.
- Failure of a switch may fail the network.
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Categories : Computer Science
Recent edits by: TheGuyLoveNY