Internet, Intranet and Extranet

Internet, Intranet and Extranet

1. Internet

   • Characteristics
     • What is it?
       • Vast computer communication network
       • uses a protocol called TCP/IP
     • Does anyone own it?
       • No one own the internet because it is a 'network of networks'.
       • Organisations, companies and governments own their particular networks.
         • Each network is connected to thousands of other networks to form the internet.
       • The key is that all the networks use the TCP/IP protocol to communicate
     • What makes it work?
       • Companies called internet service providers provide everyday users with the connectivity they need to get on the Internet.
         • Connection can be made by normal telephone line using a home router.
       • Businesses wanting a faster connection use a leased line.
         • Connection can also be made through the mobile phone network.
       • There are major telecom companies who provide the 'backbone' of the system.
         • They own the communication equipment, cabling, satellite and undersea data links that make it all work.
         • There are content providers in the form of web sites, video services, telephone services that are the reason people want to use it in the first place.
       • The internet should be thought of as an 'enabling technology'. It does nothing of itself, but brings people, companies and organisations together so they can interact.
         • The Internet is an 'open' network because any computer with appropriate communications equipment can connect to it.
   • Purpose
     • Email
       • Requires a dedicated email client application to send and receive emails
         • Emails can also be purely a web based service. In which case a standard web browser is sufficient to send and receive emails
     • File Transfer
       • FTP is used to upload and download files from an online server.
       • Cloud services offer file storage and synchronisation between computers
     • Real time chat
       • Also called 'Instant Messaging'. Most are mainly text based but some offer WebCam connections as well.
       • Unlike email and file transfers, there is not just a single protocol in use.
         • Many commercial providers use their own propriety protocol which means that a person using one service cannot easily exchange chat with someone using another service.
     • World Wide Web
       • The fundamental application needed is a 'Web Browser' application that can interpret the HTTP protocol being used for standard web pages.
         • Most browser applications also allow extensions to be installed within the browser to allow multi-media content to be viewed.
     • Video and Audio streaming
       • Music and films are streamed directly from the internet for instant viewing
       • Streaming means the content is not actually stored - it plays and its gone
       • A good, fast connection is needed for high bandwidth feeds, along with the appropriate streaming application and equipment.
     • VoIP
       • This is a telephone service that works over the internet. Short for 'Voice over Internet Protocol'.
       • You need a dedicated VoIP application running on the computer to make a connection

2. Intranet

   • Characteristics
     • It is sometimes required for companies to have a private system that offers the same services as the internet.
     • The characteristics are almost the same as the internet. It uses TCP/IP protocol to allow internal computers to communicate with one another.
     • The Intranet runs over a Local Area Network (LAN). For larger organisations it run on a Wide Area Network (WAN).
       • Should the LAN or WAN also be supporting other services, then the Intranet may be 'virtual network' within the LAN/WAN infrastructure.
     • On top of the Internet technology there will be a username-password system in place to authorise access.
   • Purpose
     • Virtually the same as the Internet, but for internal use only. Services include:
       • Email
       • File Transfer
       • Real time chat including
       • World Wide Web
       • Video and Audio streaming services
     • Each service requires at least one server to provide the service e.g. Web server and Email servers.
     • It is unlikely that the video and audio services are there for entertainment.
       • They can be used to stream business multimedia - for instance the marketing departments' latest advertising work or dedicated video training packages streamed to the employee's computer.
   • Advantages of an Intranet
     • In theory every employee could use to Internet to get the same services. But an Intranet has the following advantages:
       • Commercial data is kept secure
       • Emails remain private and may also be encrypted
       • High bandwidth. No connection limits unlike the Internet
       • Reliable. The company will have dedicated IT personnel to keep things running smoothly. No one owns the Internet so there is no 'Quality of Service' guarantee.

3. Extranet

   • An Extranet is one where people from outside the organisation can connect to the internal Intranet.
     • External suppliers may have been set to allow them to communicate via the company Intranet.
       • Remote business offices may be set up to use an intranet. Employees on business travel may use an Extranet.
   • Employees using an extranet are not connected directly to the LAN or WAN but instead are able to establish a connection with the correct equipment and authorisation.
   • Methods:
     • Mobile Phone
       • A sales person on the road wants to connect to the company Intranet. They use the mobile phone network to contact the company's secure server. An application running on their laptop then goes through the authorisation procedure. once the secure server confirms that everything is correct, the sales person will be able to use the Intranet as if they were back in the office.
     • Virtual Private Network
       • A connection to the company's secure server is made through the normal Internet. But now the secure server and the laptop will exchange secret keys which they use to encrypt all communication between the two.
       • No one cap eavesdrop on the data being exchanged.
       • Many teleworkers use VPN to connect to their company Intranet.