IEC-802 : DATA COMMUNICATION NETWORK

Unit-1Basic concepts And ISO-OSI-Model

QAZI SAEED AHMADASSISTANT PROFESSORDEPARTMENT OF ELECTRONICS & COMMUNICATIN ENGINEERINGINTEGRAL UNIVERSITY LUCKNOW

A Communication Network

• Source– generates data to be transmitted

• Transmitter– Converts data into transmittable signals

• Transmission System– Carries data

• Receiver– Converts received signal into data

• Destination– Takes incoming data

Communications Tasks

Transmission system utilization Addressing

Interfacing Routing

Signal generation Recovery

Synchronization Message formatting

Exchange management Security

Error detection and correction Network management

Flow control

Simplified Communications Model - Diagram

Simplified Data Communications Model

Networking

• Point to point communication not usually practical– Devices are too far apart– Large set of devices would need impractical

number of connections• Solution is a communications network

– Wide Area Network (WAN)– Local Area Network (LAN)

Wide Area Networks

• Large geographical area• Crossing public rights of way• Rely in part on common carrier circuits• Alternative technologies

– Circuit switching– Packet switching– Frame relay– Asynchronous Transfer Mode (ATM)

Local Area Networks

• Smaller scope– Building or small campus

• Usually owned by same organization as attached devices

• Data rates much higher• Usually broadcast systems• Now some switched systems and ATM are

being introduced

LAN Configurations

• Switched– Switched Ethernet

• May be single or multiple switches– ATM LAN– Fibre Channel

• Wireless– Mobility– Ease of installation

Metropolitan Area Networks

• MAN• Middle ground between LAN and WAN• Private or public network• High speed• Large area

NetworkingConfiguration

Line Configuration

Point-to-Point Line Configuration

Multipoint Line Configuration

Network Topology

Mesh Topology

Mesh Topology

Star Topology

Tree Topology

Ring Topology

Hybrid Topology

Transmission modes

Simplex

Half-Duplex

Full-Duplex

ISO-OSI Model

OOO OSI MODEL

OSI LAYERS

An Exchange using OSI Model

Physical Layer

Duties

• 1. Physical Characteristics of Interfaces and Medium

• 2. Representation of Bits• 3. Data Rate• 4. Synchronization of Bits• 5. Line Configuration• 6. Physical Topology• 7. Transmission Mode

Data Link Layer

Duties

• 1. Framing• 2. Physical Addressing• 3. Flow Control• 4. Error Control• 5. Access Control

Data Link Layer example

Network Layer

Duties

• 1. Logical Addressing• 2. Routing

Transport Layer

Duties

Network Layer Example

Transport Layer

WCB/McGraw-Hill The McGraw-Hill Companies, Inc., 1998

Session Layer

Presentation Layer

Application Layer

Summary of Layer Functions

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