Overview (kỹ THUẬT TRUYỀN số LIỆU SLIDE)

Overview of Data Communication and Computer Networks... Data Communication: DefinitionTransfer of data from one device to another via some form of transmission medium.. Transfer of data

Overview of Data Communication and Computer Networks

Motivations

 Efficient way to share resources

 Cost – less expensive

Data Communication: Definition

Transfer of data from one device to another via

some form of transmission medium.

Transfer of data from one device to another via

some form of transmission medium.

how

are Hi,

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User

Communications Characteristics

 Effectiveness of a data communications system depends on 4 characteristics:

 Delivery: correct destination, user…

 Accuracy: accurate data reception at destination.

 Timeliness: same order without significant delay  real-time

transmission.

 Jitter: variation in the packet arrival time

 Bit patterns, Graphics formats JPG/GIF/etc

 Audio → Samples of continuous signal

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2

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Protocols and Standards

 Protocol

 A set of rules governing data communications

 Syntax: format of data block

 Semantics: meaning of each section

 Timing: speed and sequencing

 Standards

 De facto (in practice) standards

→ not approved but widely adopted

 De jure (in law) standards

Direction of Data Flow

 Simplex: One direction only

data flow

Keyboard

data flow

Direction of Data Flow

 E.g., walkie-talkies

data flow at time 1

data flow at time 2

Direction of Data Flow

 E.g., telephone

 Can be emulated on a single communication link using various methods

data flow

data flow

Types of Connections

 Point-to-point

 Multipoint (multidrop)

Point-To-Point Connection

Multipoint Connection

Wireless

Point-to-Point Connection

Fully Connected Mesh Topology

A

C B

D E

Fully Connected Mesh Topology

Fully Connected Mesh Topology

Star Topology

Switch

Star Topology

Hub

Bus Topology

Drop line

Tap

Terminator

Bus Topology

Bus Topology

 Difficult to isolate fault

 Break in the bus cable stops all

Ring Topology

Network Categories

 Local Area Network (LAN)

 Metropolitan Area Network (MAN)

Local Area Networks

 Network in a single office, building, or campus

Wide Area Networks

 Network providing long-distance communication over a country, a continent, or the whole world

Metropolitan Area Networks

 Network extended over an entire city

 Each stamped with

source and destination

addresses

telephon e switch

Network of Networks

Company A

Network Interface Card (NIC)

Company B

 How to allow devices from different standards to communicate

 Gateways/routers – devices capable of communicating in

several standards



The Internet

 The largest internetwork (network of networks) in the world

 Devices communicating with TCP/IP protocol suite

Stanford

UC Santa Barbara

U of Utah