27-07-2011, 09:55 AM
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Networking
Networking refers to creating networks.
A network is a group of devices linked to each other.
Computers are widely used to communicate by connecting them together.
This process is called computer networking.
A collection of computers connected to one and another is called a computer network.
Advantages of Computer Networking:
It allows different computers to communicate with one another.
It makes sharing of data and resources much easier.
It saves time and money.
Terminology of Networks
Server
The main computer from which all the other computers share information is known as the Server. The server serves all the nodes that are connected in the network.
Node:
A computer terminal attached to a network that shares information is a called a Node. It I also known as a Workstation.
Network Interface Unit (NIU):
It is a device used for connecting the server and the workstations. It helps in the communication between the server and the nodes.
Types of Networks
Based on the number of computers attached and the area in which they are spread out, networks can be divided into three types :
Local Area Network (LAN),
Metropolitan Area Network (MAN),
Wide Area Network (WAN).
Local Area Network (LAN)
A small group of computers connected in a localized area is called a Local Area Network (LAN).
It connects computers and devices in a limited geographical area such as home, school, computer laboratory or office building.
The defining characteristics of LAN, include their usually higher data-transfer rates, smaller geographical area, and lack of a need for leased telecommunication lines.
Different computers in this type of network are connected together by physical media like wires, cables, etc. LANs are usually installed by small organizations like schools, offices, hospitals etc.
Metropolitan Area Network (MAN)
A metropolitan area network (MAN) is a computer network that usually spans a city or a large campus.
A MAN usually interconnects a number of local area networks using a high-capacity backbone technology, such as fiber-optical links.
The technology used in MAN is similar to that of LAN but it covers a larger area as compared to LAN. A simple example of a Metropolitan Area Network is a Cable TV Network.
Wide Area Network (WAN)
The networks spread across cities and countries are known as Wide Area Networks. A wide area network (WAN) is a computer network that covers a broad area.
The computers are separated by large distances in different cities, states, countries and continents and are connected to each other through cables and even wireless communication channels. The internet which is spread throughout a world is an example of a Wide Area Network (WAN).
Components of a Computer Network
The main components essential for the successful operationing of a computer network can be divided into two main types.
These are :
HARDWARE COMPONENTS
SOFTWARE COMPONETS
Hardware Components
Hardware components in a computer network include :
computer systems (server or clients),
shared resources, like printers, scanners, etc,
physical media that connects them.
The various computers on a network are either named as servers or clients. Different computers that access shared resources on the network are called Clients. Servers are the computers that receive requests from network users (clients) and make the shared resources available to them.
Software Components
The software components required to run a computer network are of two types. These are :
Protocols,
Network Software
The protocols specify the rules, procedures and conventions for communication and data transfer over the network. An example of a protocol is TCP/IP. TCP stands for Transmission Control Protocol and IP stands for Internet Protocol.
Network software is the software that performs various network related functions such as data routing and error detection etc.
Topology of Networks
In a Local Area Network (LAN) environment, the nodes can be interconnected in different ways. The pattern of interconnection of nodes using cables in a network is called Network Topology.
There are three basic topologies :
Bus Topology,
Star Topology,
Ring Topology.
Bus Topology
In a Bus network, also known as Linear network, all the computers and peripheral devices are connected to one single cable called the Bus.
In this type of network, computers can be easily added or removed from the network. The failure of a single node does not affect the performance of the rest of the network.
Star Topology
In a Star Network the server is placed at the center to which all the other nodes are connected. In this type of topology, it is easy to add or remove nodes.
A star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages.
The star topology reduces the chance of network failure by connecting all of the systems to a central node.
Data on a star network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, or concentrator manages and controls all functions of the network.
Ring Topology
In a Ring Topology the nodes are connected in a circular chain in which each node is connected to the next. The last node is connected to the first node.
It is difficult to add or remove nodes in this type of a structure. If any one node fails, the whole of the network goes down.
A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring.
Data travels from node to node, with each node along the way handling every packet.
Because a ring topology provides only one pathway between any two nodes, ring networks may be disrupted by the failure of a single link.
A node failure or cable break might isolate every node attached to the ring.
Communication Channels
All networks need to be linked to each other. Media or channels refer to the wires, cables or any other means by which data travels from the source to the destination.
The most commonly used media are :
Twisted Pair Cable,
Coaxial Cable,
Fiber Optic Cable,
Wireless Links.
Twisted Pair Cable
Twisted Pair Cable normally consists of strands of copper wire, insulated with plastic sheet and then twisted around each other.
This is the most commonly used media.
It is easy to install, has low weight and is flexible.
It is not capable of carrying data over long distances.
In video applications that send information across multiple parallel signal wires, twisted pair cabling can introduce signaling delays known as skew which results in subtle color defects and ghosting due to the image components not aligning correctly when recombined in the display device.
Coaxial Cable
Coaxial Cable consists of a solid wire core surrounded by a wire mesh with an insulator in between.
It is commonly used in the Cable TV networks.
A coaxial Cable can carry more data than twisted pair wire and is less susceptible to interference. It is more expensive as compared to twisted pair wire.
Coaxial cable is used as a transmission line for radio frequency signals, in applications such as feed lines connecting radio transmitters and receivers with their antennas, computer network (Internet) connections, and distributing cable television signals.
One advantage of coax over other types of radio transmission line is that in an ideal coaxial cable the electromagnetic field carrying the signal exists only in the space between the inner and outer conductors.
Optical Fiber Cable
An Optical Fiber Cable is a thin strand of glass that transmits pulsating beams of light.
Fiber Optic Cables have a complete immunity to noise.
They are also very fragile, so they needed to be handled very carefully.
An Optical Fiber is a flexible, transparent fiber made of very pure glass not much bigger than a human hair that acts as a waveguide to transmit light between the two ends of the fiber.
The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics.
Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths than other forms of communication.
Fiber Optics are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference. Optical fiber typically consists of a transparent core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by total internal reflection.
Wireless Links
Wireless communications rely on radio signals for transmitting data. Wireless communication is becoming increasingly popular. The advantage of wireless communication is the flexibility that it offers in terms of the network layout. There are four common applications of wireless communication in the field of computer networking. These are :
Office LAN can use radio signals to transmit data between nodes.
Cellular telephone equipment can be used along with a modem to connect computer systems so that business people can stay in touch with their offices.
Local Area Networks can be connected using microwave transmission within the metropolitan area.
Satellites and microwaves are used to connect WANs covering large distances.
Networking
Networking refers to creating networks.
A network is a group of devices linked to each other.
Computers are widely used to communicate by connecting them together.
This process is called computer networking.
A collection of computers connected to one and another is called a computer network.
Advantages of Computer Networking:
It allows different computers to communicate with one another.
It makes sharing of data and resources much easier.
It saves time and money.
Terminology of Networks
Server
The main computer from which all the other computers share information is known as the Server. The server serves all the nodes that are connected in the network.
Node:
A computer terminal attached to a network that shares information is a called a Node. It I also known as a Workstation.
Network Interface Unit (NIU):
It is a device used for connecting the server and the workstations. It helps in the communication between the server and the nodes.
Types of Networks
Based on the number of computers attached and the area in which they are spread out, networks can be divided into three types :
Local Area Network (LAN),
Metropolitan Area Network (MAN),
Wide Area Network (WAN).
Local Area Network (LAN)
A small group of computers connected in a localized area is called a Local Area Network (LAN).
It connects computers and devices in a limited geographical area such as home, school, computer laboratory or office building.
The defining characteristics of LAN, include their usually higher data-transfer rates, smaller geographical area, and lack of a need for leased telecommunication lines.
Different computers in this type of network are connected together by physical media like wires, cables, etc. LANs are usually installed by small organizations like schools, offices, hospitals etc.
Metropolitan Area Network (MAN)
A metropolitan area network (MAN) is a computer network that usually spans a city or a large campus.
A MAN usually interconnects a number of local area networks using a high-capacity backbone technology, such as fiber-optical links.
The technology used in MAN is similar to that of LAN but it covers a larger area as compared to LAN. A simple example of a Metropolitan Area Network is a Cable TV Network.
Wide Area Network (WAN)
The networks spread across cities and countries are known as Wide Area Networks. A wide area network (WAN) is a computer network that covers a broad area.
The computers are separated by large distances in different cities, states, countries and continents and are connected to each other through cables and even wireless communication channels. The internet which is spread throughout a world is an example of a Wide Area Network (WAN).
Components of a Computer Network
The main components essential for the successful operationing of a computer network can be divided into two main types.
These are :
HARDWARE COMPONENTS
SOFTWARE COMPONETS
Hardware Components
Hardware components in a computer network include :
computer systems (server or clients),
shared resources, like printers, scanners, etc,
physical media that connects them.
The various computers on a network are either named as servers or clients. Different computers that access shared resources on the network are called Clients. Servers are the computers that receive requests from network users (clients) and make the shared resources available to them.
Software Components
The software components required to run a computer network are of two types. These are :
Protocols,
Network Software
The protocols specify the rules, procedures and conventions for communication and data transfer over the network. An example of a protocol is TCP/IP. TCP stands for Transmission Control Protocol and IP stands for Internet Protocol.
Network software is the software that performs various network related functions such as data routing and error detection etc.
Topology of Networks
In a Local Area Network (LAN) environment, the nodes can be interconnected in different ways. The pattern of interconnection of nodes using cables in a network is called Network Topology.
There are three basic topologies :
Bus Topology,
Star Topology,
Ring Topology.
Bus Topology
In a Bus network, also known as Linear network, all the computers and peripheral devices are connected to one single cable called the Bus.
In this type of network, computers can be easily added or removed from the network. The failure of a single node does not affect the performance of the rest of the network.
Star Topology
In a Star Network the server is placed at the center to which all the other nodes are connected. In this type of topology, it is easy to add or remove nodes.
A star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages.
The star topology reduces the chance of network failure by connecting all of the systems to a central node.
Data on a star network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, or concentrator manages and controls all functions of the network.
Ring Topology
In a Ring Topology the nodes are connected in a circular chain in which each node is connected to the next. The last node is connected to the first node.
It is difficult to add or remove nodes in this type of a structure. If any one node fails, the whole of the network goes down.
A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring.
Data travels from node to node, with each node along the way handling every packet.
Because a ring topology provides only one pathway between any two nodes, ring networks may be disrupted by the failure of a single link.
A node failure or cable break might isolate every node attached to the ring.
Communication Channels
All networks need to be linked to each other. Media or channels refer to the wires, cables or any other means by which data travels from the source to the destination.
The most commonly used media are :
Twisted Pair Cable,
Coaxial Cable,
Fiber Optic Cable,
Wireless Links.
Twisted Pair Cable
Twisted Pair Cable normally consists of strands of copper wire, insulated with plastic sheet and then twisted around each other.
This is the most commonly used media.
It is easy to install, has low weight and is flexible.
It is not capable of carrying data over long distances.
In video applications that send information across multiple parallel signal wires, twisted pair cabling can introduce signaling delays known as skew which results in subtle color defects and ghosting due to the image components not aligning correctly when recombined in the display device.
Coaxial Cable
Coaxial Cable consists of a solid wire core surrounded by a wire mesh with an insulator in between.
It is commonly used in the Cable TV networks.
A coaxial Cable can carry more data than twisted pair wire and is less susceptible to interference. It is more expensive as compared to twisted pair wire.
Coaxial cable is used as a transmission line for radio frequency signals, in applications such as feed lines connecting radio transmitters and receivers with their antennas, computer network (Internet) connections, and distributing cable television signals.
One advantage of coax over other types of radio transmission line is that in an ideal coaxial cable the electromagnetic field carrying the signal exists only in the space between the inner and outer conductors.
Optical Fiber Cable
An Optical Fiber Cable is a thin strand of glass that transmits pulsating beams of light.
Fiber Optic Cables have a complete immunity to noise.
They are also very fragile, so they needed to be handled very carefully.
An Optical Fiber is a flexible, transparent fiber made of very pure glass not much bigger than a human hair that acts as a waveguide to transmit light between the two ends of the fiber.
The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics.
Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths than other forms of communication.
Fiber Optics are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference. Optical fiber typically consists of a transparent core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by total internal reflection.
Wireless Links
Wireless communications rely on radio signals for transmitting data. Wireless communication is becoming increasingly popular. The advantage of wireless communication is the flexibility that it offers in terms of the network layout. There are four common applications of wireless communication in the field of computer networking. These are :
Office LAN can use radio signals to transmit data between nodes.
Cellular telephone equipment can be used along with a modem to connect computer systems so that business people can stay in touch with their offices.
Local Area Networks can be connected using microwave transmission within the metropolitan area.
Satellites and microwaves are used to connect WANs covering large distances.
