Data:
Information presented in whatever form is agreed upon by the parties creating and using the data
Data communication:
Exchange of data between two devices
Via some form of transmission medium
Fundamental characteristics of data communication:
Delivery
Accuracy
Timeliness
Jitter : Variation in the packet arrival time
Data Flow
Simplex:
Unidirectional
As on a one-way street
Half-duplex:
Both transmit and receive possible, but not at the same time
Like a one-lane road with two-directional traffic
Walkie-talkie, CB radio
Full-duplex:
Transmit and receive simultaneously
Like a two-way street, telephone network
Channel capacity must be divided between two directions
Protocol
Protocol : rule
A set of rules that govern data communication
For communication to occur, entities must agree upon a protocol
Key elements of a protocol
Syntax: structure or format of data
Semantics: meaning of each section in the structure
Timing: when and how fast data should be sent
Internet Standards
IETF (Internet Engineering Task Force)
Internet Draft
working document with no official status
with a 6-month lifetime
RFC (Request for Comment)
Edited, assigned a number, and made available to all interested parties