Data Communications ผู้สอน : ผศ. ดร. ศักดิ์ชัย ทิพย์จักษุรัตน์ (2D/1) ผศ. ดร. อรฉัตร จิตต์โสภักตร์ (2D/2) Tel: (02) TEXTBOOK: B. A. Forouzan, Data Communications and Networking, 4 th edition McGRAW-HILL GRADING POLICY: Assignment 20% Midterm Exam 30% Final Exam50%

List of Studied Topics Basic of Communication: Chapter 1, 3, 4, 5, 6, 7 Introduction (1), Signal (3), Digital Transmission (4), Analog Transmission (5), Multiplexing (6), Transmission media (7) Standard Communication Protocol: Chapter 2 and Appendix C Network Model (TCP/IP) (2) and OSI model (Appendix C) Switching, Telephone network, and High Speed Digital Access : Chapter 8-9 Data flow control: Chapter Error detection & correction (10), Flow control (11), Point-to-Point Access (12), Multiple Access (13), LAN (14), Wireless LAN (15)

WCB/McGraw-Hill Data Communication System Components

Data Representation Text ASCII (8 bits): (The American Standard Code for Information Interchange) ASCII Table -> Appendix Unicode (16 bits): Represents symbols belong to languages other than English Images Videos Audio

Direction of Data Flow between two devices

Figure 1.2 Simplex

Figure 1.3 Half-duplex

Figure 1.4 Full-duplex

1.2 Networks Distributed Processing Physical Structures Categories of Networks

Physical Structure

Point-to-Point Connection Guided medium link Unguided medium

WCB/McGraw-Hill Multipoint Connection

Categories of Topology

Figure 1.7 Categories of topology

Mesh Topology - Physical Structure: point-to-point - number of link = n(n-1)/2 n = number of devices Any two devices have their own link - Advantages Transmission speed ( สูงมาก ) Reliable (damage link) ( สูงมาก ) Privacy, Security ( สูงมาก ) Fault Detection ( ง่ายมาก ) - Disadvantages Cost (Installation and Maintenance) ( สูงมาก ) Expansion and Modification ( ยุ่งยากมาก )

Star Topology - number of link = n n = number of devices Centralize communication - Advantages Cost (Installation and Maintenance) ( น้อย ) Reliable (damage link) ( ปานกลาง ) Expansion and Modification ( ง่าย ) Fault Detection ( ง่าย ที่ Hub) - Disadvantages Intelligent central controller Limited number of ( ตามจำนวน port ของ Hub) - Physical Structure: point-to-point

Tree Topology - point-to-point Multi-level star - Disadvantages Intelligent central controller Limited number of devices - number of link = n + m n = number of devices m = number of secondary hubs - Advantages Cost (Installation and Maintenance) Reliable (damage link) ( ปานกลาง ) Expansion and Modification Fault Detection Group Priority

Ring Topology - number of link = n n = number of devices - point-to-point Loop around - Advantages Cost (Installation and Maintenance) ( ปานกลาง ) Expansion and Modification Fault Detection ( ปานกลาง ) Multiaddressing - Disadvantages Unreliable (damage link; unidirectional ring) Extra-cost for repeater Get rid of unused data

Bus Topology - multipoint - number of link = 1 Share a single medium Unreliable (damage link) Expansion and Modification Fault Detection - Disadvantages Transmission speed Limited number of devices - Advantages Lowest Cost Efficient utilization of the medium

Performance Comparison of each network topology Cost Device, Connection, and Maintenance (Low -> High): Bus < Star < Ring < Tree < Mesh Transmission Speed (High -> Low): Mesh > Star > Tree > Ring > Bus Expansion and Modification (Easy -> Hard): Star > Ring > Bus > Tree > Mesh Fault detection (Easy -> Hard): Mesh > Star > Tree > Ring > Bus Reliable (High -> Low): Mesh > Star >Tree > Ring > Bus Privacy and Security (High -> Low): Mesh > Star>Tree > Ring > Bus

Categories of Networks

Figure 1.12 Categories of networks

Figure 1.13 LAN - Area < 2 mi (2-3 km) - Data rate 100, 1000 Mbps

Figure 1.13 LAN (Continued)

Figure 1.14 MAN - Area: Town, City -Example: part of the telephone company network providing High speed DSL / Cable TV

Figure 1.15 WAN

28 Classifying Networks by Area A personal area network (PAN) refers to the small computer networks that are found in private homes. A Campus area network (CAN)

1.3 The Internet A Brief History The Internet Today

A Brief History of the Internet (cont.) กลาง 1960 ยุคของคอมพิวเตอร์ Mainframe ARPA (Advanced Research Project Agency) in Department of Defense (DoD) ปี 1967 ARPANET – Host attached to specialized computer called IMP (Interface Message Processor)

A Brief History of the Internet (cont.) ตั้งแต่ปี 1969 ARPANET มีการใช้งานจริง UCLA (University of California at Los Angeles) UCSB (University of California at Santa Barbara) SRI (Standard Research Institute) University at Utah Software คือ Network Control Protocol (NCP) ปี 1972 Internetting Project ปี 1973 – Protocols to achieve end-to-end delivery of packets TCP IP – Internetworking protocol

Figure 1.16 Internet today ISP: Internet Service Providers

ประสิทธิภาพของการส่งผ่านข้อมูล ถูกที่หมายปลายทาง ข้อมูลที่ได้รับต้องถูกต้องแม่นยำ ปราศจาก ข้อผิดพลาด เวลาในการส่งเหมาะสม WCB/McGraw-Hill

Criteria ในการวัดประสิทธิภาพ ของระบบ network -Throughput - Delay

1.4 Protocols and Standards Protocols ( เกณฑ์วิธี, โพรโท คอล ) Standards Standards Organizations Syntax, Semantics, Timing

WCB/McGraw-Hill - Standard not been approved by organization body - Widespread - Standard been approved by organization body

ตัวอย่างขององค์กรที่ทำหน้าที่ จัดทำ standard ISO -> OSI (Open Systems Interconnection) ITU-T -> V series, X series, ISDN, ANSI -> ASCII code IEEE -> LAN standard EIA -> physical connection interfaces & signalling FCC -> A government agency that regulates radio, television, and Telecommunication WCB/McGraw-Hill (International Organization for Standardization) (International Telecommunication Union-Telecommunication Standards Sector) (Electronic Industries Association) (Institute of Electrical and Electronics Engineers) เดิม CCITT : Consultative Committee for International Telegraph and Telephony (American National Standard Institute) (Federal Communications Commission)

Forum Frame Relay ATM Forum ISOC & IETF (Internet Society and Internet Engineering Task Force) (Asynchronous Transfer Mode)