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Communications And The Internet

Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

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Page 1: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

CommunicationsAnd

The Internet

Page 2: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

What is Communications?

Communication is the process of conveying information from a sender to a receiver with the use of a medium in which the communicated information is understood by both sender and receiver. It is a process that allows organisms to exchange information by several methods.

Page 3: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Why do Organizations Communicate?

Share information and Data Resources

Monitor Activities

Process Sales and Orders

Share the use of Applications and Processes

Communicate with its Staff and Partners

Communicate with its Customers

Perform Transactions with its Vendors

Page 4: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Computers make it possible for organizations to Communicate from point A to B in-house as well as over a wide geography

A BMedium

This is made possible via a set of Hardware Devices and

Communication Software

Page 5: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Organizations Communicate using Computers to Various Departments

SalesAccounting

Production

Page 6: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Computers that communicate within an organization form a NETWORK

Page 7: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

A computer network, also referred to as just a network, consists of two or more computers, and typically other devices as well (such as printers, external hard drives, modems and routers), that are linked together so that they can communicate with each other and thereby exchange commands and share data, hardware and other resources.

Page 8: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

The devices on a network are referred to as nodes. They are analogous to the knots in nets that have traditionally been used by fishermen and others. Nodes can be connected using any of various types of media, including twisted pair copper wire cable, optical fiber cable, coaxial cable and radio waves.

Page 9: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

What is a Network Topology?

In communication networks, a topology is a usually schematic description of the arrangement of a network, including its nodes and connecting lines (media). There are two ways of defining network geometry: the physical topology and the logical (or signal) topology.

Page 10: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Types of Topologies

Ring

Bus

Star

Mesh

Tree

Page 11: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

The Ring Topology

In the ring network topology, the workstations are connected in a closed loop configuration. Adjacent (Neighbouring) pairs of workstations are directly connected. Other pairs of workstations are indirectly connected, passing data through one or more intermediate nodes.

Page 12: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

The Bus Topology

In the bus network topology, every workstation is connected to a main cable called the bus. Therefore, in effect, each workstation is directly connected to every other workstation in the network.

Page 13: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

The Star Topology

In the star network topology, there is a central computer or server to which all the workstations are directly connected. Every workstation is indirectly connected to every other through the central computer.

Page 14: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

The Mesh Topology

The mesh network topology employs either of two schemes, called full mesh and partial mesh. In the full mesh topology, each workstation is connected directly to each of the others. In the partial mesh topology, some workstations are connected to all the others, and some are connected only to those other nodes with which they exchange the most data.

Page 15: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

The Tree Topology

The tree network topology uses two or more star networks connected together. The central computers of the star networks are connected to a main bus. Thus, a tree network is a bus network of star networks.

Page 16: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

N.B. Logical (or signal) topology refers to the nature of the paths the signals follow from node to node. In many instances, the logical topology is the same as the physical topology. But this is not always the case. For example, some networks are physically laid out in a star configuration, but they operate logically as bus or ring networks.

Page 17: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Types of Networks

TAN – Tiny Area Network

LAN – Local Area Network

WAN – Wide Area Network

MAN – Metropolitan Area Network

Page 18: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Tiny Area Network

A Connection of four(4) or less Computers

Page 19: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Local Area Network

A Network that connects computers within the same building or Area such as a Home or small office.

Page 20: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Wide Area Network

A Network that spans a wide Geography, such as City to City or Country to Country.The Internet is currently the world’s largest Wide Area Network.

Page 21: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Metropolitan Area Network

A metropolitan area network (MAN) is designed to serve a town or city, and a campus area network is designed to serve a university or other educational institution.

Page 22: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Data can be communicated from one terminal to the central computer to other terminals through different media. These media are known as data communication channels there are cable, WiFi, microwave, satellite and fiber optics.

Communications Media

Page 23: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Cable is the most popular and widely used medium to transmit data from one location to another.

Telephone Line

Twisted Wire Pair

Coaxial Cable

Page 24: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Picture of Telephone Line

Page 25: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Picture of the Twisted Wire Pair

Page 26: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Picture of Coaxial Cable

Page 27: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

WiFi

Wi-Fi (short for "wireless fidelity") is a term for certain types of wireless local area network (WLAN) that use specifications in the 802.11 family. 802.11 is a set of rules That govern the use of these WiFi Frequencies.

Wi-Fi has gained acceptance in many businesses, agencies,schools, and homes as an alternative to a wired LAN. Many airports, hotels, and fast-food facilities offer public access to Wi-Fi networks. These locations are known as hot spots.

Page 28: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Diagram of a WiFi Configuration

Page 29: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Microwaves

The term microwave refers to electromagnetic energy having a frequency higher than 1 gigahertz (billions of cycles per second), corresponding to wavelength shorter than 30 centimeters.Microwave signals propagate in straight lines and are affected very little by the troposphere.

Page 30: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Satellites

In general, a satellite is anything that orbits something else, as, for example, the moon orbits the earth. In a communications context, a satellite is a specialized wireless receiver/transmitter that is launched by a rocket and placed in orbit around the earth. There are hundreds of satellites currently in operation. They are used for such diverse purposes as weather forecasting, television broadcast, amateur radio communications, Internet communications, and the Global Positioning System, (GPS).

Page 31: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Fiber Optics

Fiber optic (or "optical fiber") refers to the medium and the technology associated with the transmission of information as light impulses along a glass or plastic wire or fiber. Fiber optic wire carries much more information than conventional copper wire and is far less subject to electromagnetic interference. Most telephone company long-distance lines are now fiber optic.

Page 32: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Picture of Fiber Optic Wires

Page 33: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Rules that Govern the Communication of Computers

A network protocol is a formal set of rules, conventions and data structure that governs how computers and other network devices exchange information over a network. In other words, protocol is a standard procedure and format that two data communication devices must understand, accept and use to be able to talk to each other

Computers uses network protocols as a means of communicating:

Page 34: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

What is the Internet?

The Internet is the worldwide, publicly accessible network of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP). It is a "network of networks" that consists of millions of smaller domestic, academic, business, and government networks, which together carry various information and services, such as electronic mail, online chat, file transfer, and the interlinked Web pages and other documents of the World Wide Web.

Page 35: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

A little history

The Internet started in the 1960s as a way for government researchers to share information. Computers in the '60s were large and immobile and in order to make use of information stored in any one computer, one had to either travel to the site of the computer or have magnetic computer tapes sent through the conventional postal system.Another catalyst in the formation of the Internet was the heating up of the Cold War. The Soviet Union's launch of the Sputnik satellite spurred the U.S. Defense Department to consider ways information could still be disseminated even after a nuclear attack. This eventually led to the formation of the ARPANET (Advanced Research Projects Agency Network), the network that ultimately evolved into what we now know as the Internet. ARPANET was a great success but membership was limited to certain academic and research organizations who had contracts with the Defense Department. In response to this, other networks were created to provide information sharing.

Page 36: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

The Internet Today

The Internet today is a large-scale network of millions of computers that allows continuous communication across the globe. The various applications of the Internet are:

•The World-Wide Web (the web or WWW)•Electronic Mail (E-Mail)•File Transfer Protocol (FTP)•Internet Relay chat (IRC)•USENET (a news service)

Page 37: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

The World Wide Web

The www is the reason the Internet has become as popular as it has. This is the part of the Internet that the majority of users see — the websites and the pagesthat make them up. The web is the most widely used service of the Internet, accessed through a web browser like Internet Explorer or Mozilla Firefox. These pieces of software are gradually integrating other parts of the Internet into them (most notably email and ftp), so that eventually we will have one interface to the entire array of services the Internet offers.

Page 38: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Electronic Mail (E-Mail)

Electronic Mail works in much the same way as traditional mail (now charmingly labeled 'snail-mail') does. Anyone is allowed to sign up for an email address and then people can send you messages, or attach files from their computer and send them too. The main benefit of email is the close to instantaneous delivery of messages that occurs. You can send an email to the other side of the world and it will arrive in less than a minute. You can also sign up to weekly newsletters and have information you want delivered right to your computer.

E.g. Of an email address is : [email protected] N.B. Both sender and recipient must possess an email address.

Page 39: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

File Transfer Protocol (FTP)

While web pages are transferred between computers using the http protocol, other types of files are sent using FTP. People can share files, like music and videos, among each other and the rest of the world by uploading them to a server and allowing others to download them to their own computers.

Page 40: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Internet Relay chat (IRC)

IRC is a service that allows you to connect to your chosen channel and talk in real-time to people with the same interests as you. There is MSN Messenger Service as well as yahoo and AOL.

Page 41: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

USENET (a news service)

USENET (Unix User Network) is a system of bulletin boards where you and anyone else can post messages and people will read and reply to them. As with IRC, you will find boards set up for all sorts of groups of people. The search engine Google has set up a web-interface for these discussion boards.

Page 42: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Other Communications Terminologies

Modem: This is short for Modulator-Demodulator, it is a device usedTo connect computers to a telephone line and distribute informationVia a remote (distant) connection.

Page 43: Communications And The Internet - Welcome to St. · PDF file · 2012-11-27Communications. And . The Internet. What is Communications? ... the physical topology and the logical

Conclusion

Communications have made massive advancement in the 21st century, with the advent of the internet and equivalent hardware, there is a

convergence of production, entertainment and education.

These utilities enhance our lifestyles leading us to an unknown world of speed

And information.