1. Communication Fundamentals Yi Liang 9/9/2015

2. Fundamentals  Layered protocols Build Message System call Send over network d Process A Process B

3. Fundamentals  Layered protocols  meaning of the bits being sent?  which is the last bit of the message?  How can it detect if a message has been damaged or lost, and what should it do if it finds out?  How long are numbers, strings, and other data items, and how are they represented? …. …

4. Fundamentals  Layered protocols

5. Fundamentals  Layered protocols  Protocol: formalized rules that govern the format, contents, and meaning of the messages.  To allow a group of computers to communicate over a network, they must all agree on the protocols to be used  Connection oriented protocols  telephone  Connectionless protocols  Dropping a letter in a mailbox

6. Fundamentals  Layered protocols  Benefits:  Each layer has its own protocols that can be changed without affecting other layers.

7. Fundamentals  Lower level protocols  physical layer protocol: standardizing the electrical, mechanical, and signaling interfaces  data link layer: detect errors and correct it.(checksum)  Network layer : routing (connectionless IP protocol)

8. Fundamentals  Transport Protocols  transport layer: provide a reliable connection (TCP, UDP)

9. Fundamentals  Higher- Level Protocols  Session layer: dialog control, synchronization.  Presentation layer: define message format  Application layer: container for all applications and protocols

10. Fundamentals  Drawbacks :  there is no clear distinction between applications, application-specific protocols, and general-purpose protocols.  For example: FTP, ftp program.

11. Fundamentals  Current reference network model

12. Fundamentals  Type of communication  Persistent VS Transient  Synchronous VS Asynchronous  Discrete VS Streaming

13. Fundamentals  The most recent trend and future.  Quantum protocols  Relationship-oriented network  Content centric network

14. What’s your idea ?