LE427 Data communication and networks Jarree Chaicharn, Ph.D. รศ ดร จรี ไชยชาญ

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 –HDLC Midterm examination 29 Feb.

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

–Midterm Examination40 % –Homework & Quiz 10% –Final Examination50 %

What is data communication? Components –Message –Sender –Receiver –Medium –Protocol SenderReceiver Medium

–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 Source encoding Channel encoding Line encoding Modulation Channel Receiver Source 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 dataH6 L7 data L6 data To session layer

Session Layer Provides the control structure for communication between applications; Establishes, Manages and terminates a session Synchronizes H5 L6 data L5 data syn To transport layer

Transport layer End-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 To network layer

Network layer Source-to destination delivery of a packet Network addressing Routing: route the packets to their final destination DataH3 L4 data L3 data To data link layer

Addressing R R A P E M G H T2DataAP10 20 T2DataAP99 33 T2DataAP66 95 A= network address 10=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 DataT2S D L3 data To physical layer Sender and destination 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 Transmission medium L2 data

The Internet model OSIInternet Application Presentation Session TransportTransport, TCP NetworkNetwork, IP Data linkInterface 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