Communication Fundamentals Yi Liang 9/9/2015
Fundamentals Layered protocols Build Message System call Send over network d Process A Process B
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? …. …
Fundamentals Layered protocols
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
Fundamentals Layered protocols Benefits: Each layer has its own protocols that can be changed without affecting other layers.
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)
Fundamentals Transport Protocols transport layer: provide a reliable connection (TCP, UDP)
Fundamentals Higher- Level Protocols Session layer: dialog control, synchronization. Presentation layer: define message format Application layer: container for all applications and protocols
Fundamentals Drawbacks : there is no clear distinction between applications, application-specific protocols, and general-purpose protocols. For example: FTP, ftp program.
Fundamentals Current reference network model
Fundamentals Type of communication Persistent VS Transient Synchronous VS Asynchronous Discrete VS Streaming
Fundamentals The most recent trend and future. Quantum protocols Relationship-oriented network Content centric network
What’s your idea ?