1. COE 342: Data & Computer Communications (T042) Dr. Marwan Abu-Amara
Chapter 1: Data Communications & Networking Overview

2. COE 342 (T042) – Dr. Marwan Abu-Amara
Course Outline
Data Communications & Networking Overview (Ch. 1)
Protocol Architecture (Ch. 2)
Data Transmission (Ch. 3)
Guided and Wireless Transmission (Ch. 4)
Signal Encoding Techniques (Ch. 5)
Digital Data Communication Techniques (Ch. 6)
Data Link Control (Ch. 7)
Multiplexing (Ch. 8)
COE 342 (T042) – Dr. Marwan Abu-Amara

3. COE 342 (T042) – Dr. Marwan Abu-Amara
Agenda
Introduction
Communications Model
Main blocks and functionality
Communication Tasks
Data Communications
Data Communication Networking
Wide Area Networks
Circuit switching
Packet switching
Frame Relay
ATM
Local Area Networks
COE 342 (T042) – Dr. Marwan Abu-Amara

4. COE 342 (T042) – Dr. Marwan Abu-Amara
Introduction
Fundamental purpose of communications system is exchange of data between 2 parties
3 general areas:
Data Communications
Transmission of signals in reliable & efficient manner
Covers signal transmission, transmission media, signal encoding, interfacing, data link control, multiplexing
Networking
Covers technology & architecture of communication networks
Divided into LANs & WANs
Protocols
COE 342 (T042) – Dr. Marwan Abu-Amara

5. Simplified Communications Model - Diagram
COE 342 (T042) – Dr. Marwan Abu-Amara

6. A Communications Model
Source
Generates data to be transmitted
Transmitter
Converts data into transmittable signals (modulation, encoding, …)
Transmission System
Carries data
Receiver
Converts received signal into data (opposite to “Transmitter” role)
Destination
Takes incoming data
COE 342 (T042) – Dr. Marwan Abu-Amara

7. COE 342 (T042) – Dr. Marwan Abu-Amara
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
COE 342 (T042) – Dr. Marwan Abu-Amara

8. Simplified Data Communications Model
May involve buffering and/or encoding of digital data (Ch. 5)
Modulated signal, s(t), matched to media (Ch. 3 & 4)
Transmission Impairments: noise, distortion, etc. (Section 3.3)
Ideally received info, m’, should be identical to original input info, m (Ch. 7)
If not, error correction may help restore m (Ch. 7)
Else, retransmission is required (Ch. 7)
COE 342 (T042) – Dr. Marwan Abu-Amara

9. COE 342 (T042) – Dr. Marwan Abu-Amara
Networking
Point to point communication not usually practical
Devices are too far apart
Large set of devices would need impractical number of connections (full connectivity of N nodes is N  (N – 1) / 2)
Solution is a communications network
Wide Area Network (WAN)
Local Area Network (LAN)
COE 342 (T042) – Dr. Marwan Abu-Amara

10. COE 342 (T042) – Dr. Marwan Abu-Amara
Wide Area Networks
Large geographical area
Rely in part on common carrier circuits
Alternative technologies
Circuit switching
Packet switching
Frame relay
Asynchronous Transfer Mode (ATM)
COE 342 (T042) – Dr. Marwan Abu-Amara

11. COE 342 (T042) – Dr. Marwan Abu-Amara
Circuit Switching
Dedicated communications path established for the duration of the conversation
e.g. telephone network
COE 342 (T042) – Dr. Marwan Abu-Amara

12. COE 342 (T042) – Dr. Marwan Abu-Amara
Packet Switching
Data sent out of sequence
Small chunks (packets) of data at a time
Packets passed from node to node between source and destination
Used for terminal to computer and computer to computer communications
COE 342 (T042) – Dr. Marwan Abu-Amara

13. COE 342 (T042) – Dr. Marwan Abu-Amara
Frame Relay
Packet switching systems have large overheads to compensate for errors
Modern systems are more reliable
Errors can be caught in end system
Most overhead for error control is stripped out
Variable-length packets (called frames)
COE 342 (T042) – Dr. Marwan Abu-Amara

14. Asynchronous Transfer Mode (ATM)
Evolution of frame relay
Combines circuit switching & packet switching
Little overhead for error control
Fixed-length packets (called cells)
Anything from 10Mbps to Gbps
Constant data rate while using packet switching technique
COE 342 (T042) – Dr. Marwan Abu-Amara

15. COE 342 (T042) – Dr. Marwan Abu-Amara
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
COE 342 (T042) – Dr. Marwan Abu-Amara

16. COE 342 (T042) – Dr. Marwan Abu-Amara
LAN Configurations
Switched
Switched Ethernet
May be single or multiple switches
ATM LAN
Fibre Channel
Wireless
Mobility
Ease of installation
COE 342 (T042) – Dr. Marwan Abu-Amara

17. Metropolitan Area Networks (MAN)
Middle ground between LAN and WAN
Private or public network
High speed
Large area
COE 342 (T042) – Dr. Marwan Abu-Amara

18. Networking Configuration
COE 342 (T042) – Dr. Marwan Abu-Amara