COMMUNICATION AND NETWORK CONCEPT TS
Network
The collection of interconnected computers is called a
computer network.
Two computers are said to be interconnected if they are
capable of sharing and exchanging information.
Need
Resource Sharing
Reliability
Cost Factor
Communication Medium
Resource Sharing means to make all programs, data and peripherals available to anyone on the network
irrespective of the physical location of the resources and the user.
Reliability means to keep the copy of a file on two or more different machines, so if one of them is
unavailable (due to some hardware crash or any other them its other copy can be used.
Cost factor means it greatly reduces the cost since the resources can be shared
Communication Medium means one can send messages and whatever the changes at one end are done
can be immediately noticed at another.
Evolution of Networking
1. ARPANET:In 1969, The US govt. formed an agency named ARPANET (Advanced Research Projects
Agency NETwork) to connect computers at various universities and defense agencies. The main objective
of ARPANET was to develop a network that could continue to function efficiently even in the event of a
nuclear attack.
2. Internet (INTERconnection NETwork : The Internet is a worldwide network of computer networks.
It is not owned by anybody.
3. Interspace:InterSpace is a client/server software program that allows multiple users to communicate
online with real – time audio, video and text chat in dynamic 3D environments.
SWITCHING TECHNIQUES
Switching techniques are used for transmitting data across networks.
Different types are :
1. Circuit Switching: In the Circuit Switching technique, first, the complete end-to-end transmission path
between the source and the destination computers is established and then the message is transmitted
through the path. The main advantage of this technique is guaranteed delivery of the message. Mostly
used for voice communication.
2. Message Switching: In the Message switching technique, no physical path is established between
sender and receiver in advance. This technique follows the store and forward mechanism.
3. Packet Switching: In this switching technique fixed size of packet can be transmitted across the
network.
Comparison between the Various Circuit Message Packet
Switching Techniques: Criteria Switching Switching Switching
Path established in advance Yes No No
Store and forward technique No Yes Yes
Message follows multiple routes No Yes Yes
, DATA COMMUNICATION TERMINOLOGIES
Data channel :- The information / data carry from one end to another in the network by
channel.
Baud & bits per second bps : - It’s used to measurement for the information carry of a
communication channel.
Measurement Units :- bit
1 Byte= 8 bits
1 KBPS ( Kilo Byte Per Second= 1024 Bytes
1 Kbps (kilobits Per Second = 1024 bits
1 Mbps ( Mega bits Per Second )=1024 Kbps
Bandwidth :- It is amount of information transmitted or receives per unit time.
Transmission media:
1. Twisted pair cable: - It consists of two identical 1 mm thick copper wires
insulated and twisted together. The twisted pair cables are twisted in order to
reduce crosstalk and electromagnetic induction.
Advantages:
i It is easy to install and maintain.
ii It is very inexpensive
Disadvantages:
i It is incapable to carry a signal over long distances without the use of repeaters.
ii Due to low bandwidth, these are unsuitable for broadband applications.
2. Co-axial Cables: It consists of a solid wire core surrounded by
one or more foil or braided wire shields, each separated from the
other by some kind of plastic insulator. It is mostly used in the
cable wires.
Advantages:
i Data transmission rate is better than twisted pair cables.
ii It provides a cheap means of transporting multi -channel
television signals around metropolitan areas.
Disadvantages:
i Expensive than twisted pair cables.
ii Difficult to manage and reconfigure.
3. Optical fiber: - An optical fiber consists of thin glass fibers that can
carry information in the form of visible light.
Advantages:
i Transmit data over long distance with high security.
ii Data transmission speed is high
iii Provide better noise immunity
iv) Bandwidth is up to 10 Gbps.
Disadvantages:
i Expensive as compared to other guided media.
ii Need special care while installation?
4. Infrared: - The infrared light transmits data through the air and can
propagate throughout a room, but will not penetrate walls. It is a secure medium of signal transmission.
The infrared transmission has become common in TV remotes, automotive garage doors, wireless
speakers etc.
Network
The collection of interconnected computers is called a
computer network.
Two computers are said to be interconnected if they are
capable of sharing and exchanging information.
Need
Resource Sharing
Reliability
Cost Factor
Communication Medium
Resource Sharing means to make all programs, data and peripherals available to anyone on the network
irrespective of the physical location of the resources and the user.
Reliability means to keep the copy of a file on two or more different machines, so if one of them is
unavailable (due to some hardware crash or any other them its other copy can be used.
Cost factor means it greatly reduces the cost since the resources can be shared
Communication Medium means one can send messages and whatever the changes at one end are done
can be immediately noticed at another.
Evolution of Networking
1. ARPANET:In 1969, The US govt. formed an agency named ARPANET (Advanced Research Projects
Agency NETwork) to connect computers at various universities and defense agencies. The main objective
of ARPANET was to develop a network that could continue to function efficiently even in the event of a
nuclear attack.
2. Internet (INTERconnection NETwork : The Internet is a worldwide network of computer networks.
It is not owned by anybody.
3. Interspace:InterSpace is a client/server software program that allows multiple users to communicate
online with real – time audio, video and text chat in dynamic 3D environments.
SWITCHING TECHNIQUES
Switching techniques are used for transmitting data across networks.
Different types are :
1. Circuit Switching: In the Circuit Switching technique, first, the complete end-to-end transmission path
between the source and the destination computers is established and then the message is transmitted
through the path. The main advantage of this technique is guaranteed delivery of the message. Mostly
used for voice communication.
2. Message Switching: In the Message switching technique, no physical path is established between
sender and receiver in advance. This technique follows the store and forward mechanism.
3. Packet Switching: In this switching technique fixed size of packet can be transmitted across the
network.
Comparison between the Various Circuit Message Packet
Switching Techniques: Criteria Switching Switching Switching
Path established in advance Yes No No
Store and forward technique No Yes Yes
Message follows multiple routes No Yes Yes
, DATA COMMUNICATION TERMINOLOGIES
Data channel :- The information / data carry from one end to another in the network by
channel.
Baud & bits per second bps : - It’s used to measurement for the information carry of a
communication channel.
Measurement Units :- bit
1 Byte= 8 bits
1 KBPS ( Kilo Byte Per Second= 1024 Bytes
1 Kbps (kilobits Per Second = 1024 bits
1 Mbps ( Mega bits Per Second )=1024 Kbps
Bandwidth :- It is amount of information transmitted or receives per unit time.
Transmission media:
1. Twisted pair cable: - It consists of two identical 1 mm thick copper wires
insulated and twisted together. The twisted pair cables are twisted in order to
reduce crosstalk and electromagnetic induction.
Advantages:
i It is easy to install and maintain.
ii It is very inexpensive
Disadvantages:
i It is incapable to carry a signal over long distances without the use of repeaters.
ii Due to low bandwidth, these are unsuitable for broadband applications.
2. Co-axial Cables: It consists of a solid wire core surrounded by
one or more foil or braided wire shields, each separated from the
other by some kind of plastic insulator. It is mostly used in the
cable wires.
Advantages:
i Data transmission rate is better than twisted pair cables.
ii It provides a cheap means of transporting multi -channel
television signals around metropolitan areas.
Disadvantages:
i Expensive than twisted pair cables.
ii Difficult to manage and reconfigure.
3. Optical fiber: - An optical fiber consists of thin glass fibers that can
carry information in the form of visible light.
Advantages:
i Transmit data over long distance with high security.
ii Data transmission speed is high
iii Provide better noise immunity
iv) Bandwidth is up to 10 Gbps.
Disadvantages:
i Expensive as compared to other guided media.
ii Need special care while installation?
4. Infrared: - The infrared light transmits data through the air and can
propagate throughout a room, but will not penetrate walls. It is a secure medium of signal transmission.
The infrared transmission has become common in TV remotes, automotive garage doors, wireless
speakers etc.
