CS3591 COMPUTER NETWORKS IA1 st

  Data Communications: exchange of data between two devices through  a transmission medium.

Characteristics:DATA(DELIVERY,ACCURACY,TIMELINESS,AVOIDING JITTER)

  • Delivery – Data reaches correct destination.

  • Accuracy – Data is error-free.

  • Timeliness – Data arrives on time.

  • Jitter – Variation in packet arrival time.

Components , 1) Message 2) Sender 3) Receiver 4) Medium 5) Protocol (SRM PM)

  • Message – Data/information (text, numbers, images, sound).

  • Sender – Device that sends data.

  • Receiver – Device that receives data.

  • Medium – Physical path (twisted pair, coaxial, fiber-optic, radio).

  • Protocol – Rules for communication.


Data Representation(Text, Numbers, Images, Audio, Video.) TNIAV

  • Text – Bit pattern, ASCII.

  • Numbers – Bit pattern, no ASCII.

  • Images – Bit pattern, pixels.

  • Audio – Continuous sound/music.

  • Video – Continuous picture/movie.

Data Flow  (SHF – Simplex, Half-duplex, Full-duplex.)

  • Simplex – One-way communication (unidirectional). Example: CPU → Monitor, Keyboard → Monitor.

  • Half-Duplex – Two-way communication, but one at a time (t1 send, t2 receive). Example: Walkie-talkie.

  • Full-Duplex – Two-way simultaneous communication, sharing channel capacity. Example: Telephone.

Network – (group of interconnected computers)Set of interconnected devices (nodes) via a communication medium.
Node – Any device in the network (e.g., computer, printer, etc.).


Network Criteria: PRS – Performance, Reliability, Security.

  • Performance – Measured by transit time & response time; affected by users, medium, hardware, software.

  • Reliability – Measured by accuracy, failure rate, establishment time, robustness.

  • Security – Protects data from unauthorized access.

Physical Structure – Network attributes: connection type & topology.