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Communication software and protocols

Communication software and protocols. Sara Tang 5D (35). Oh?what on earth is communication software?. The application used to transmit digital messages from one user to another through a computer network. Services provided by communication software. Broadcasting messages e.g. online forum

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Communication software and protocols

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  1. Communication software and protocols Sara Tang 5D (35)

  2. Oh?what on earth is communication software? • The application used to transmit digital messages from one user to another through a computer network.

  3. Services provided by communication software • Broadcasting messages e.g. online forum • Data/information sharing e.g. chat rooms • Real-time communcation e.g. MSN

  4. Type of communication

  5. Type of communication

  6. MSN

  7. iVisit

  8. Skype

  9. Why communication software? • Fast transmission speed • Low transmission cost • Support mulitimedia message • Transmitted information is mostly reusable

  10. What are communication protocols?hmmm… • a set of rules about data formatting or signalling that is understood by all the communication devices =>a common standard understood by all communication devices in a computer network

  11. to transmit a network application’s data over a computer network • Used by communication software to work with communication devices.

  12. Application of common communication protocols

  13. Open system interconnection (OSI)model • When data is transmitted from one computer to another ,the data must go through the OSI model • It is a way of sub-dividing a communication into smaller parts called layers. • a layer provides services to the layer above it and receives services from the layer below it.

  14. The 7 layers • Application layer • Presentation layer • Session layer • Transport layer • Network layer • Data link layer • Physical Layer

  15. Application layer • Provides interface for application software to set up communication with another application software

  16. Presentation layer • Converts data into a format that can be understood by the receiver’s system

  17. Session layer • sets up and maintains the communication linkages between two computers during data transmission • It establishes, manages and terminates the connections between the local and remote application.

  18. Transport layer • transfer of data between end users Transport header (TH) +data =datagram • TH contains the transportation information eg. The protocol used • Datagram transmitted over the internet using TCP will be divided into smaller packets before transmitting to the next layer

  19. Data is sent in packets -allows a path to be shared among users in a computer network. -avoids repeatedly sending large files -when a packet is corrupted or missing during transmission,only the corrupted packet instead of the whole data file will be resent.

  20. Network layer • Determines the routing and forwarding of data. • Network Header +datagram=packet -NH contains network address information eg.IP address

  21. Data link layer • For network addressing ,error detection and correction • Data link header+Packet+Data link trailer=frame

  22. Physical layer • Transfers frames physically on a LAN • defines the relationship between a device and a transmission medium eg.copper or optical cable

  23. An overview about OSI model

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