LE427 Data communication LE427 Data communication and networksand networks

LE427 Data communication LE427 Data communication and networksand networks

Jarree Chaicharn, Ph.D.Jarree Chaicharn, Ph.D.รศ ดร จร� ไชยชาญรศ ดร จร� ไชยชาญ

http://www.jarree.ee.engr.tu.ac.th/LE517/

Syllabus• 3. Course Outline • 3.1 Introduction to Data Communication • 3.2 Communication system• - Source Coding • - Channel Coding• - Line Coding• - Data transmission• 3.3 Data Communication Interfacing

– Data Link control– HDLCMidterm examination 29 Feb.

– Packet switching

– X.25 – LAN Technology– Internetworking– TCP/IP– Network security– Delay models in data network

– Midterm Examination 40 % – Homework & Quiz 10%– Final Examination 50 %

What is data communication?

• Components– Message– Sender– Receiver– Medium– Protocol

Sender ReceiverMedium

– Protocol• A set of rules that govern data

communication– Syntax: data format– Semantics: control information for

coordination and error handling– Timing: speed matching and sequencing

Communication system

SourceSource

encoding

Channel

encoding

Line

encoding

Modulation

Channel

ReceiverSource

decoding

Channel

decoding

Line

decoding

Demodulation

Data networks• Performance

– Number of users– Type of transmission medium– Capability of the connected hardware– Efficiency of the software

• Reliability– Frequency of failure– Recovery time of a network after failure– Unforeseen damage (Fire, earthquake)

• Security– Unauthorized access– Viruses

Standards organizations

• The international Telecommunications Union-Telecommunication Standards sector (ITU-T formerly CCITT)

– Related to the united nations that develops standards for telecommunications (V series, V.32 V.33 V.42 and X series X.25 X.400 X.500)

Standards organizations

• The international standards organization (ISO)

Dedicated to worldwide agreement on international standards in variety of fields

Open system interconnection (OSI) model

OSI model Is a layered framework for the

design of network system

To open communication between different systems without requiring changes to the logic of underlying hardware and software

Layers of the OSI model

7 Application layer

6 Presentation layer

5 Session layer

3 Network layer

2 Data Link layer

1 Physical layer

User support layers

Network support layers

4 Transport layer

Application Layer• Provide user interfaces and

support for services User

Application layer

L7 data

To presentation layer

Presentation layer

• Translation (format and code conversion)

• Encryption• Compression

Encoded, encrypted,compressed data

H6

L7 data

L6 data

To session layer

Session LayerProvides the control structure for

communication between applications;

• Establishes, Manages and terminates

a session• Synchronizes

H5

L6 data

L5 data

syn syn

syn

To transport layer

Transport layerEnd-to end delivery, The entire message

arrives at the receiving transport layer without error

• Service-point addressing; specific process • Divides the message from session layer into

transmittable segments• Connection control• Flow control (End-to-End)• Error control (End-to-End)Transmission control protocol (TCP)

L5 data

H4-1

H4-2

H4-3

L4 data

L4 data

L4 data

To network layer

Network layerSource-to destination delivery of a packet• Network addressing• Routing: route the packets to their final

destination

Data H3

L4 data

L3 data

To data link layer

Addressing

R

R

A

P

E

M

G

H

1020

99

33

66

95

T2 Data A P 10 20

T2 Data A P 99 33

T2 Data A P 66 95

A= network address10=Physical address

Data link layer• Responsible for node-to-node delivery, error-

free, reliable transmission (HDLC)– Framing: divides the stream of bits – Physical addressing: Sender and destination

address– Flow control: Prevent overwhelming the receiver– Error control: Detect and retransmit damaged or

lost frame (Trailer)– Access control DataT2 S D

L3 data

To physical layer

Sender anddestination address

Physical layer

• Mechanical and Electrical specifications of the interface and transmission medium

• Defines the procedures and functions that physical devices and interface has to perform for transmission to occur

EIA-232 10011000111100101

Transmission medium

L2 data

The Internet modelOSI Internet

Application Application

Presentation

Session

Transport Transport, TCP

Network Network, IP

Data link Interface

Physical

Get Web Page

User Web Browser Application

Get Web Page

TCP Header

TCP Layer

Get Web Page

TCP Header

IP Header

Get Web Page

TCP Header

IP Header

LAN Header

LAN Trailer

IP Layer

Interface Layer

Local Router

Get Web Page

TCP Header

IP Header

WAN Header

Interface Layer

WAN

Get Web Page Web Page

Get Web Page

TCP Header

TCP Layer

Get Web Page

TCP Header

IP Header

Get Web Page

TCP Header

IP Header

LAN Header

LAN Trailer

IP Layer

Interface Layer

Remote Router

Get Web Page

TCP Header

IP Header

WAN Header

Interface Layer