1. Chapter 1. Introduction

2. 1. DATA COMMUNICATIONS Telecommunication: communication at a distance Data: information presented in whatever form is agreed upon by the parties creating and using the data Data communications: exchange of data between two users / devices via some form of transmission medium such as a wire cable – Delivery – Accuracy – Timeliness – Jitter

3. Five components of data communication Message Sender Receiver Medium for transmission Protocol: set of (explicit and implicit) rules

4. Data Representation Text: ASCII, Unicode, … Numbers Images Audio Video

5. Data flow (simplex, half- and full-duplex) Communication can be two-way by nature

6. 2. NETWORKS Network: a set of devices (often referred to as users or nodes) connected by communication links – A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network Performance of network – Throughput – Delay – Reliability (Accuracy and freq. of failures) – Security

7. Physical Structure of Network Types of connections – Point-to-point, multi-point Types of topologies – Mesh, star, bus, ring Covering areas – LAN, MAN, WAN

8. Types of connections

9. Categories of Topology Mesh Star Bus Ring

10. Hybrid Topology Star + Bus

11. Covering Area LAN: Local Area Network WAN: Wide Area Network MAN: Metropolitan Area Network – between LAN and WAN, e.g., Campus networks

12. Inter-network A heterogeneous network made of four WANs and two LANs

13. 3. THE INTERNET Impact of “the Internet” – Revolutionized many aspects of our daily lives: business, leisure, communications, … History – ARPANET Project (1960s) led by Advanced Research Project Agency (ARPA) in the Dept. of Defense (DoD) to establish reliable networks – Evolves in 1970s and 1980s – TCP/IP

14. Hierarchical organization of the Internet

15. 4. PROTOCOLS AND STANDARDS Protocols: a set of rules for communications – Syntax – format – Semantics – meaning / interpretation – Timing – when data should be sent, and how fast they can be sent Standards – Essential in guaranteeing interoperability, and in creating and maintaining an open and competitive market

16. Standards Two types – De facto: not formally approved, but everyone accepts MS Word (except Korea), MS Excel – De jure: formally approved WIPI (middleware platform in Korea) Standards Organizations – ISO, ITU-T, CCITT, ANSI, IEEE, EIA, … Internet Standards – Internet Draft, Request for Comment (RFC)

17. Homework Exercise in Chap. 1 – 16 – 17 – 22 – 25