Communications and networks


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Communications and networks

  1. 1. GROUP 2 Nurul Aminah Thaqif Nurul Nadiah binti Ramli Aminah binti Mustaffa Muhammad Thaqif bin Md Rajab
  3. 3. Introduction
  5. 5. COMMUNICATION CHANNELS -Twisted-pair cable -Coaxial cable -Fiber-optic cable -Radio frequency -microwave -satellite -infrared
  6. 6. COMMUNICATION CHANNELS CHANNEL DESCRIPTION Twisted pair Twisted copper wire,used for standard telephone lines and Ethernet cables. Coaxial cable Solid copper core,more than 80 times the capacity of twisted pair. Fiber-optic cable Light carries data ,more than 26,000 times the capacity of twisted pair. Radio frequency Radio waves connect wireless devices including cell phones and computer components. Microwave High-frequency radio waves ,travels in straight line through the air. Satellite Microwave relay station in the sky ,used by GPS devices. Infrared Infared light travels in a straight line.
  7. 7. CONNECTION DEVICES MODEMS -modula-demodulator. -Modulation: Process of converting digital to analog and demodulation is vice versa. -Enable digital microcomputers to communicate across different media,including telephone wires, cable lines, and radio waves. CONNECTION SERVICE -For years, individuals relied on dial-up services using existing telephones and telephone modems to connect to internet. This type of service has been replaced by higher-speed connection services including DSL,cable,satellite, and cellular services. TYPES: -Telephone modem -DSL(digital subscriber line) -Cable modem -Wireless modem TYPES: -Digital subscriber line(DSL) service -Cable service -Satellite connection service -cellular service
  8. 8. Description types of modems Telephone modem -Used to connect a computer directly to a telephone line. -internal : system board –external : system unit DSL(digital subscriber line) modem -Uses standard phone lines to create a high- speed connection directly to phone company’s offices.(usually external-connect to system unit using USB or Ethernet ports. Cable modem -Uses the same coaxial cable television. -creates high- speed connections like DSL using system unit’s USB or Ethernet port. Wireless modem -Known as WWAN(wireless wide area network). - Usually plug-in USB or ExpressCard device that provides very portable highspeed connectivity.
  9. 9. Description of Connection Service Digital subscriber line(DSL) service -Provided by telephone companies using existing telephone lines to provide high-speed connections. Example:ADSL(asymmetric digital subscriber line)-faster than dial-up Cable service -Provided by cable television companies using their existing television cablesfaster than DSL Satellite connection services -Use satellite to provide wireless connections-slower than DSL and cable modems-but are available almost anywhere using satellite-receiving disk. Cellular services -3G or 4G to provide wireless connectivity to the internet-not fast as the other services but are rapidly growing in popularity for mobile devices(phones and other portable devices.
  10. 10. DATA TRANSMISSION Measurement of the width or capacity of the communication channel. Voiceband Medium band Broadband Baseband
  11. 11. DATA TRANSMISSION A set of communication rules for the exchange of information. Identification Packetization
  12. 12. Networks A communication system that connects two or more computers so that they can exchange information and share resources.
  13. 13. TERM DESCRIPTION NODE Device that is connected to a network. It could be a computer, printer, or data storage device Clients A node that requests and uses resources available from other nodes. Typically, a client is a user’s microcomputer. Server A node that shares resources with other nodes. Directory server A specialized server that manages resources ,such as user accounts, for an entire network. Host Any computers system that can be accessed over a network. Switch Central node that coordinates the flow of data by sending messages directly between sender and receiver nodes. (NIC) Network interface cards Expansion cards located within the system unit that connect the computer to a network -LAN adapter (NOS) Network Control and coordinate the activities of all computers and other operating system devices on network. Network administration A computer specialist responsible for efficient network operations and implementation of new networks.
  14. 14. NETWORK ARCHITECTURE Describe how network is arranged and how resources are coordinated and shared.
  15. 15. TOPOLOGIES Describe the physical arrangement of the network.
  16. 16. • Star network -each device is connected directly to a central network switch.
  17. 17. •Tree/hierarchical network –each device is connected to a central node, either directly through one or more other devices.
  18. 18. • Mesh network -each device connected to more than one other device
  19. 19. STRATEGIES Define how information and resources are shared Strategy Description Client/server networks Clients request services; server provide services and coordination; efficient network management software; expensive. Peer-to-peer networks All nodes act as clients and servers ;easy and inexpensive; lacks security controls.
  20. 20. Organizational Networks Internet Technologies Intranet -private network within an organization that resembles the internet. -use browsers, Web sites, and Web pages Extranet -private network that connects more than one organization. -to allow suppliers and others limited accesses to their networks. -to increase efficiency and reduce costs. Network Security Firewall -consists of hardware and software that control access to a company’s intranet and other internal networks. Intrusion detection system (IDS) -work with firewalls to protect an organization’s network. Virtual private networks(VPN) -create secure private connection between a remote user and an organization’s internal network.
  21. 21. Careers in IT Network administrators -manage company’s LAN and WAN networks. -responsible for design, implementation, and maintenance of networks -Responsibilities include maintenance of both hardware and software related to a company’s intranet and Internet networks.