Saturday, 9 May 2015

Networks

1 ) What Is a Company Network?

- Computer Network: is a system that connects computers and other devices (e.g. printers, smart phones) via communications media so that data and information can be transmitted among them.

- In a computer network connected computers:
✅ Work together.
✅ Are interdependent.
✅ Exchange data with each other.

- Bandwidth: the transmission capacity of a network. It is stated in bits per second..

- Broadband: network transmission  capacity ranging from approximately one million bus (megabits/ second) up to several terabits/ second.

- Types of computer Networks:
⭐ Local Area Networks (LAN): connects two or more devices in a limited geographical region,  usually within the same building, so that every device on the network can communicate with every other device.
    • Trade-offs between: speed, distance, cost.
    • Every device in the LAN has a network interface card (NIC).
    • NIC allows the device to physically connects to the LAN's communication medium.
    • Network Server or file server: contains various software (operating system) and data for the network.

⭐ Wide Area Networks (WAN):
      • covers a large geographic area and have large capacity.
      • Provide by telecommunication companies.
      • WANs also contain routers.
  ♢ Router: is a communication processor that routes messages from LAN to the internet, across several connected LANs.

⭐ Enterprise Networks: a network encompassing an organization, composed of interconnected multiple LANs and WANs
    • Backbone Network: are high speed central networks to which multiple smaller network connect.

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2) Network Fundamentals:

- Networks transmit information with two types of signals:
  1. Analog Signals: are continuous waves that transmit information by altering the characteristics of the waves.
      • Have two parameters: - amplitude (higher the wave).
                                           - frequency (more closely packed).

  2. Digital Signals: are discrete pulses that are either ON or OFF, representing a series of bits (0s and 1s).


 ♢ Modem (modulator- demodulator): is to converts digital signals to analog signal and vice versa.
     D➡A= Modulation.
     A➡D= Demodulation.
  - Dial up modem has transmission speed of 56 Kbs.
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♣ Communication Media and Channels: pathway for communicating data from one location to another.

 • Wireline Media (cable):
1. Twisted - pair wire.                                    
2. Coaxial cables➡ made of copper.
3. Fiber - optic cable.




Wireless Media (Broadcast):
1. Microwave. 
2. Satelite.
3. Radio.
4. Infrared.

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♣ Transmission Technologies:
   ▶Digital subscriber line ( DSL): a technology that provide high- speed transmission of digital data over existing copper telephone lines.
   Example: Oman tel ADSL offers bandwidth up to 40 Maps.

   ▶Asynchronous Transfer Mode (ATM): a technology that provides support for data, video, and voice transmissions on a single communications.
       - Can transmit up to 2.5 Gbps.
       - Required fiber- optic cables.
       - More expensive than DSL.

  ▶Synchronous Optical Network (SONET): is an interface standard designed to carry large volumes of traffic over relatively long distance using fiber- optic lines.


  ▶T- Carrier System: is a digital transmission system that defines circuits that operate at different rates, all of which are multiple of the basic 64 Kbps used to transport single voice call.
 
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♣ Network Protocols: set of rules and procedures that govern transmission across a network.
   ▶Ethernet: a common LAN protocol.
   ▶Transmission Control Protocol/ Internet Protocol (TCP/IP): is the protocol of the internet.  
       - Internet Protocol: is responsible for disassembling, delivery, and reassembling the data during transmission.
      - Packet switching: technology that breaks blocks of next into small, fixed bundles of data and routes them in the most economical way through any available communication channel.
      - Hypertext transfer protocol (HTTP): defines how messages are formulated and how they are interpreted by their receivers.
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♣Types of Network Processing:
- Distributed processing: Divide processing work among two or more computers.
    1. Client/ Server computing: links two or more computers in an arrangement in which some machines, called Server, provide computing services for user PCs, called clients.

    2. Peer-to peer (P2P) processing: is a type of client/Server distribution processing where each computer acts as both a client and a server.
         Example: Microsoft Share Point.

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3) The Internet and the World Wide Web:

- The internet ("the Net"): is a global WAN that connects approximately one million organizational computer Networks in more than 200 countries on all continents, including Antarctica, and plays a role in the daily routine of almost 2 billion people.
 - The internet grew out of an experimental project of the Advanced Research Project Agency (ARPA) of the US Department of Defense.

Intranet: is a network that uses Internet Protocol so that users can take advantage of familiar applications and work habits.
 • Extranet: connects parts of the intranets of different organization's.
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♣ Accessing the Internet:
      1. Connecting via Online Service:
        • Internet Service Provider (ISP): is a telecommunication company that offers Internet connections for a fee .
          Example: www.thelist.com.


        - ISPs connect to one another through NAPs.

         • Network access points (NAPs): are exchange points for Internet traffic.

 
     2. Connecting via Other Means.
   
     3. Addresses on the Internet:
          • Internet Protocol (IP) address: an assigned address that distinguishes each computer on the Internet from all other computers.
             - Example: 135.62.128.91


          • The internet Corporation for Assigned Names (ICANN):
              - www.icann.org.
              - Responsible for coordinating IP addresses throughout the world.
              - ICANN accredits certain companies called registrars to registrars to register names                    (called Domain Name) that are equivalent to the IP address.

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♣ The World Wide Web:
     World Wide Web (WWW, W3): is a system of universally accepted standards for storing, retrieving, formatting, and displaying information via a client/ server architecture.

      Website: all of the pages of a particular company or individual.

      Home page: is a text and graphic screen display that usually welcome the user and provides basic information on the organization that has established the page.

      Webmaster: the person in charge of an organization's website.

      Uniform Resource Locator (URL): points to the address of a specific resource on the web.

     Browsers: a software applications that help the users access the web primarily.

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4) Network Applications:

♣ Discovery: the internet allows users to browse and search data sources, in all topic areas, on the Web.
      ♢ Search Engines: is a computer program that searches for specific information by key words and reports the results.

       
      ♢ Metasearch Engine: search several engines at once and integrate the findings of the various search engines to answer queries posted by users.

      ♢ Publication of Material in Foreign Language:
               - Translation products include:
                    • Altavista.
                    • Google.
                    • Trados.

       ♢ Portals: a Web- based, personalized gateway to information and knowledge that provides relevant information from different IS systems and the internet using advanced search and indexing techniques.
              • Four types of portals:
                 1. Commercial (public) portals: offer content for diverse communities and are the most popular portals on the Internet.
                 2. Affinity portals: offer a single point of entry community of interest, such as a                          hoppy group or political party.
                 Example: http://www.kooora.com.
                 3. Corporate/ Enterprise portals: offer a personalized single point of access to information located within the organization.
                 4. Industrywide portals: offer a single point of entry to information for an entire industry.
                Example: www.truck.net
                - Offers information about professional drivers, owner/operators, trucking companies, trucking jobs, drivers (virtual) round table.
            • Another type:
                 - Mobile portals: are portals that are accessible from mobile devices.

Portals

♣ Communication:
         ♢ Electronic Mail (e-mail): transmission of electronic messages over the Internet.
              - The largest- volume application running over the Internet.
              - 90% of companies conduct business transaction via e- mail.

        ♢ Web- Based Call Centers (customer call center): are services that provide effective personalize customer contact as an important part of Web based customer support.

        ♢ Electronic Chat Room: a virtual meeting place where groups of regulars come to "gab"/ E- Chitchat.

       ♢ Voice Communication:
            - Internet Telephony/ Voice - over Internet Protocol (VoIP): digitizes your analog voice signals, sections them into packets, and sends them over the Internet.

      ♢ Unified Communications (UC):
          - simplified and integrates all forms of communications, voice mail, fax, chat, e-mail, instant messaging, short message service, presence (location) services, and videoconferencing- on a common hardware and software platform.

♣ Collaboration: refers to efforts of two or more entities (individuals, teams, groups, or organizations) who work together to accomplish certain tasks.
       - Work group: refers specifically to two or more individuals who act together to perform some task.

      - Virtual group (team): is when group members are in different locations.
                  • Crowdsourcing:
                        - Synchronous collaboration: mean that all team members meet at the same time.
                        - Asynchronous collaboration: when team members cannot meet at the same time.

      - Virtual collaboration: the use of digital technologies that enable organizations or individuals to collaboratively plan, design, develop, manage and research products, services and innovative applications.

     - Workflow technologies: facilitate the movement of information as it flows thought the sequence of steps that make up an organization's work procedures. Include workflow management and workflow systems.
   
     - Groupware: software products that support groups of people who share a common task or goal and who collaborate to accomplish it.

     - Teleconferencing: the use of electronic communication that allows two or more people at different locations to hold a simultaneous conference.

     - Videoconferencing: is when participants in one location can see participants at other locations and share data, voice, picture, graphics and animation by electronic means.

     - Web conferencing: videoconferencing conducted over the Internet.

     - Real- time collaboration tools: support synchronous communication of graphical and text- based information i.e. computer- based whiteboards.

     - Telepresence systems:
          • The last version of videoconferencing.
          • Enable participants to seamlessly share data, images, graphics, and animation electronically.
   
♣ E- Learning and Distance Learning:
       • E- Learning: refers to learning supported by the web.











      • Distance Learning: refers to any learning situation in which teachers and students do not meet face- to- face.

  ✴ Benefits of E-Learning:
          ✅ Students have the flexibility of learning from any place at any time at their own pace.
          ✅ Online materials deliver high- quality, current content.
          ✅ Training costs can be reduced.

✴ Drawbacks of E- learning:
          ✖ Instructors may need training to be able to teach electronically.
          ✖ Students must be computer literate.
          ✖ There are issues with assessing students' work.

♣ Virtual Universities: are online universities in which students take classes from home or at an off- site location, via the Internet.
     - Example: http://www.open.ac.uk.


♣ Telecommuting/ Teleworking: allows workers to work anytime and any place.
      ✴ Benefits:
           • For Employees:
               - Reduced stress, improved family life.
               - Employment opportunities for single parents and persons with disabilities.
           • For Employers:
               - Increase productivity.
               - Ability to retain skilled employees.
     ✴ Drawbacks:
           • For Employees:
              - Feelings of isolation.
              - No workplace visibility.
              - Potential for slower promotions.
           • For Employers:
              - Difficulties in supervising work.
              - Potential information security problems.
              - Additional training costs.

Telecommuting

         


              



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