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The Internet is a global system of interconnected computer networks that use
the standard Internet Protocol Suite (TCP/IP) to serve billions of users
worldwide.
It is a network of networks that consists of millions of private, public,
academic, business, and government networks, of local to global scope, that
are linked by a broad array of electronic, wireless and optical networking
technologies.
The Internet carries a vast range of information resources and services, such
as the inter-linked hypertext documents of the World Wide Web (WWW) and
the infrastructure to support electronic mail.
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ROLE OF INTERNET
Linking consumers and businesses via internet.
Monitoring/maintaining customer's Web sites.
Network management/systems integration.
Backbone access services for other ISP's.
Managing online purchase and payment systems.
Benefits of Internet:
Doing fast business.Trying out new ideas.
Gathering opinions.
Allowing the business to appear alongside other established businesses.
Improving the standards of customer service/support resource.
Supporting managerial functions.
Limitations:
Security
Privacy Threats: Hackers, viruses etc.
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INTRANET
An intranet is the generic term for a collection of private computer
networks within an organization.
The intranet is to the internal system of the organization what the internet is
to its external environment.
That is it links internal data networks of the company but prevents access to
other outside the company. It also facilitates data gathering from with the
company.
For example surveys can be easily conducted through the intranet to assess
employee moral or popularity of benefit packages.
Ford's intranet success is so spectacular that the automaker's in-house
website could save billion dollars and fulfill a cherished dream of buildingcars on demand
By opening up its intranet to suppliers and coordinating the delivery and
assembly of thousands of components some auto companies tried to move
closer to manufacturing on demand.
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1
.W
orkforce productivity:Intranets can also help users to locate and view information faster and use
applications relevant to their roles and responsibilities. With the help of a web
browser interface, users can access data held in any database the
organization wants to make available, anytime and - subject to security
provisions - from anywhere within the company workstations, increasing
employees' ability to perform their jobs faster, more accurately, and with
confidence that they have the right information. It also helps to improve the
services provided to the users.
2.Time:
With intranets, organizations can make more information available to
employees on a "pull" basis (i.e., employees can link to relevant information at
a time which suits them) rather than being deluged indiscriminately by emails.
3.Business operations and management:
Intranets are also being used as a platform for developing and deploying
applications to support business operations and decisions across the inter
networked enterprise
ROLE OF INTRANET
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EXTRANET
An extranet is a private network that uses Internet protocols, network
connectivity, and possibly the public telecommunication system to securely
share part of an organizations information or operations with suppliers,
vendors, partners, customers or other businesses.
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ROLE OF EXTRANET
1. Large Volume Data Exchange
2. Information Sharing
3. Collaboration
4. Synchronized Training
5. Service co-access
6. Exclusive Info Sharing
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INTERNET, INTRANET AND EXTRANET
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Telecommunication Media
Telecommunication is the transmission of information, over significant
distances, for the purpose of communication.
In earlier times, telecommunications involved the use of visual signals, such
as beacons, smoke, semaphore telegraphs, signal flags, and optical
heliographs, or audio messages via coded drumbeats, lung-blown horns,
or sent by loud whistles, for example.
In the modern age of electricity and electronics, telecommunications now also
includes the use of electrical devices such as telegraphs, telephones, and
teletypes, the use of radio and microwave communications, as well as fiber
optics and their associated electronics, plus the use of the orbiting satellites
and the Internet.
A telecommunication network is a collection of transmitters, receivers, and
telecommunication channels that send messages to one another. Some digital
communications networks contain one or more routers that work together to
transmit information to the correct user. An analog communications network
consists of one or more switches that establish a connection between two or
more users
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Telecommunication media include twisted-pair wire, coaxial cable, and
fiber optic cables. Also included are terrestrial microwave, communications
satellite, cellular phone systems, and packet and LAN radio.
Twisted Pair wire- Ordinary telephone wire consisting of copper wire twisted
into pairs is the most widely used medium for communication.
Coaxial cable- consists of a sturdy copper or aluminium wire wrapped with
spacers to insulate and protect it. They allow high speed data transmission.And are used instead of twisted pair wire lines in high service metropolitan
areas.
Fiber Optics uses cables consisting of one or more hair thin filaments or glass
fiber wrapped in a protective packet.
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Wireless Technologies
Wireless telecommunication technologies rely on radio wave, microwave,
Infrared and visible light pulses to transport digital communications withoutWires between communication device. This includes terrestrial microwave,
communication satellite cellular and PCS telephone and pager systems,
mobile data radio, wireless LANs and various wireless internet technologies.
Terrestrial microwave involves earthbound microwave systems that transmit
high speed radio signals in a line of sight path between relay stations spaced30miles apart.
Communication satellite also use microwave radio as their telecommunication
medium.
Cellular and PCS telephone and pager system use several radiocommunication technologies.
Wireless access to the internet , intranet and extranet is growing as more.
Web enabled information appliances proliferate, smart telephones, pagers,
PDAs and other portable communication devices
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Telecommunication Processors
Telecommunication processors such as modems, multiplexers, switches and
routers perform a variety of support functions between the computer and otherdevices in a telecommunications network.
Modems- are the most common type of communication processor. They convert
the digital signals from a computer or transmission terminal at one end of a
communications link into analog frequencies that can be transmitted over
ordinary telephone lines.
Multiplexers- is a combinations processor that allows a single communications
channel to carry simultaneous data transmissions from many terminals. This is
accomplished in two ways. In FDM a multiplexer divides high speed channel into
slow speed channels.
In TDM the multiplexer divides the time each terminal can use the high speedline into very short time slots.
Internetwork processors networks are interconnected by special purpose
communication processors called internetwork processors such as switches,
routers, hubs and gateways. A switch is a communications processor that makes
connections between telecommunications circuit in a network.
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Telecommunications software is a vital component of all telecommunication
networks.
For e.g mainframe based wide area networks frequently use telecommunicationsMonitors, CICS for IBM mainframe is a typical example.
Telecommunication software packages provide a variety of communications
support services. Network management packages such as L AN network
operating systems and WAN telecommunication monitors determinetransmission
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Network Topologies
There are several types of network topologies in telecommunication network.
A star network ties end user computers to a central computer.
A ring network ties local computer processors together in a ring.
A bus network is a network in which local processors share the same bus.
Client/sever networks may use a combination of star, ring and bus approaches.
Obviously the star network is more centralized while ring and bus networks have
a more decentralized approach.
Ring and bus networks are most common in LAN network. Ring network are
most reliable and less costly for such networks.
The physical topology of a network refers to the configuration of cables,
computers, and other peripherals. Physical topology should not beconfused with logical topology which is the method used to pass
information between workstations
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BUS NETWORK-
Advantages of a LinearBus Topology-
Easy to connect a computer or peripheral to a linear bus.
Requires less cable length than a star topology.Disadvantages of a LinearBus Topology
Entire network shuts down if there is a break in the main cable.
Terminators are required at both ends of the backbone cable.
Difficult to identify the problem if the entire network shuts down.
Not meant to be used as a stand-alone solution in a large building.
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STAR NETWORK-
Advantages of a Star Topology
Easy to install and wire.
No disruptions to the network when connecting or removing devices.
Easy to detect faults and to remove parts.
Disadvantages of a Star Topology
Requires more cable length than a linear topology.
If the hub, switch, or concentrator fails, nodes attached are disabled.
More expensive than linear bus topologies because of the cost of the hubs,
etc.
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RING NETWORK-
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Advantages
Data is quickly transferred without a bottle neck. (very fast, all data traffic is in
the same direction)
The transmission of data is relatively simple as packets travel in one direction
only.
Adding additional nodes has very little impact on bandwidth
It prevents network collisions because of the media access method or
architecture required.
-Disadvantages
Data packets must pass through every computer between the sender and
recipient therefore this makes it slower.
If any of the nodes fail then the ring is broken and data cannot be transmitted
successfully.It is difficult to troubleshoot the ring.
Because all stations are wired together, to add a station you must shut down
the network temporarily.
In order for all computers to communicate with each other, all computers must
be turned on.
Total dependence upon the one cable
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OSI MODEL AND TCP/IP MODEL
The ISO has developed a seven layer Open
Systems Interconnection model to serve as
a standard model for network architecture.
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TCP/IP is internet protocol suite. It consists of five layers of protocol that can be
related to the seven layers of the OSI architecture.
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Application layer provides communications services for end user applications.
Presentation layer provides appropriate data transmission formats and codes.
Session Layer supports the accomplishment of telecommunication sessions.
Transport Layer supports the organization and transfer of data between nodes
In the network.
Network layer provides appropriate routing by establishing connections among
Network link.
Supports error free organization and transmission od data in the network.
Provides physical transmission of data on the telecommunication media in the
network.
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