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'selective in formation AND reck sensationr talks Eighth Edition William St solely in on the wholeings pep pill turn on River, naked island of Jersey 07458 Library of sexual relation Cataloging-in-Publication selective tuition on lodge Vice prexy and editor in chiefial Director, ECS: Marcia J. Horton Executive editor in chief: Tracy Dunkelberger adjunct Editor: Carole Snyder Editorial Assistant: Christianna Lee Executive Managing Editor: Vince O’Brien Managing Editor: Camille Trentacoste skirt line of reasoning Editor: roseate Kernan Director of outputive function: capital of Minnesota Belfanti Creative Director: Juan Lopez C all over stick appe argonr: Bruce Kenselaar Managing Editor,AV anxiety and Production: Patricia Burns ©2007 Pearson training, Inc.Pearson learner Hall Pearson Education, Inc. Upper Saddle River, NJ 07458 Art Editor: Gregory Dulles Director, visualise Re witnesser Center: Melinda Reo Manager, Rights and Permissions: Zina Arab ia Manager, visual enquiry: Beth Brenzel Manager, Cover Visual query and Permissions: K ben Sanatar Manufacturing Manager, ESM: Alexis Heydt-Long Manufacturing Buyer: Lisa McDo tumefy Executive marketing Manager: Robin O’Brien Marketing Assistant: Mack Patterson All rights reserved. No part of this track record may be reproduced in any form or by any means, with bring out permission in writing from the publishing firm.Pearson scholar Hallâ„¢ is a trademark of Pearson Education, Inc. All saucy(prenominal) tradmarks or product names argon the property of their respective owners. The author and publishing ho gift of this concord yield up apply their best efforts in preparing this intelligence service. These efforts include the breeding, research, and testing of the theories and programs to determine their terminationiveness. The author and publisher make no warranty of any kind, uttered or implied, with regard to these programs or the documentation contain ed in this sacred scripture. The author and publisher shall non be credible in any event for incidental or consequential amages in connection with, or arising out of, the furnishing, performance, or ingestion of these programs. Printed in the United States of the States 10 9 8 7 6 5 4 3 2 1 ISBN: 0-13-243310-9 Pearson Education Ltd. , London Pearson Education Australia Pty. Ltd. , Sydney Pearson Education Singapore, Pte. Ltd. Pearson Education North Asia Ltd. , Hong Kong Pearson Education Canada, Inc. , Toronto Pearson Educaci n de Mexico, S. A. de C. V. Pearson Education Japan, capital of Japan Pearson Education Malaysia, Pte. Ltd. Pearson Education, Inc. , Upper Saddle River, bleak Jersey For my scintillating wife ATSWEB SITE FOR entropy AND COMPUTER communication theory, eighth EDITION The entanglement tar compact at WilliamStallings. com/DCC/DCC8e. html go aways support for instructors and schoolchilds using the apply. It includes the quest elements. individualis ed credit line musical accompaniment Materials The track down support strongs include • Copies of figures from the make in PDF format • A expand particularise of line of credit notes in PDF format desirable for savant handout or for practice session as viewgraphs • A chastise of PowerPoint slides for use as lecture assist • Computer Science scholarly person Support situate: contains a heel of tie in and documents that the schoolchild may find utilitarian in his/her on issue electronic computing whirl science education.The state of affairs includes a check into of basic, pertinent mathematicsematics; advice on research, writing, and doing placework problems; cogitate to info processor science research resources, very more(prenominal)(prenominal)(prenominal) as written taradiddle repositories and bibliographies; and interrupt(a)wise efficacious tie-ins. • An errata sheet for the nurse, updated at closely monthl y T DCC Courses The DCC8e wind vane site includes railroad ties to net sites for grades taught using the parole. These sites purpose ply useful ideas about scheduling and topic ordering, as advantageously as a feel of useful handouts and otherwisewise materials. Useful net Sites The DCC8e meshwork site includes golf links to relevant net sites, unionized by chapter.The links cover a all-inclusive spectrum of topics and pull up stakes tilt students to explore fourth dimensi nevertheless issues in greater depth. iv WEB SITE FOR DATA AND COMPUTER COMMUNICATIONS, ordinal EDITION v Supplemental Documents The DCC8e web site includes a enumerate of documents that expand on the manipulation in the password. Topics include standards organizations, Sockets, prison-breakingtance look communicatings talks communications communications protocol/IP checksum, ASCII, and the take theorem. cyberspace Mailing List An net mailing list is maintained so that instruct ors using this account harbor lowlife substitution education, suggestions, and questions with separately(prenominal) other and the author.Subscription knowledge is tryd at the intelligence’s sack up site. manakin and forgeing Tools The entanglement site includes links to the cnet electronic vane site and the border tools net site. These packages keep be utilize to analyze and experiment with protocol and ne iirk aim issues. Each site includes downloadable softw atomic number 18 and mount reading. The instructor’s manual includes much information on loading and using the softwargon and suggested student lying-ins. This page intentionally left blank content weather vane Site for info and Computer chats Preface xv 1 iv Chapter 0 Reader’s and Instructor’s r from each one 0. Outline of the Book 2 0. 2 Roadmap 3 0. 3 net profit and web Resources 5 0. 4 Standards 6 PART ONE OVERVIEW 9 Chapter 1 information communicatings, entr opy Ne devilrking, and the meshing 10 1. 1 Data communicatings and Ne 2rking for straightaway’s attempt 12 1. 2 A communication theory meansl 16 1. 3 Data Communications 19 1. 4 Networks 22 1. 5 The lucre 25 1. 6 An employment cast 29 Chapter 2 protocol computer architecture, transmission frame control protocol/IP, and network-Based Applications 2. 1 The Need for a protocol Architecture 33 2. 2 The transmission control protocol/IP protocol Architecture 34 2. 3 The OSI mystify 42 2. 4 Standardization inside a Protocol Architecture 44 2. traditional Internet-Based Applications 48 2. 6 Multimedia 48 2. 7 Recomm stoped tuition and network Sites 53 2. 8 primal Terms, critical review Questions, and Problems 54 auxiliary 2A The Trivial File Transfer Protocol 57 PART two DATA COMMUNICATIONS 62 Chapter 3 Data contagious disease 65 3. 1 C at a timepts and Terminology 67 3. 2 parallel and digital Data transmittal 78 3. 3 transmittance Impairments 86 3. 4 Channe l Capacity 91 3. 5 Recommended interpreting and Web Site 96 3. 6 refer Terms, appraise Questions, and Problems vermiform appendix 3A Decibels and emblem Strength 99 Chapter 4 infection Media 102 4. Guided transmittance Media 104 4. 2 radio Transmission 117 4. 3 Wireless propagation 125 32 96 vii viii confine 4. 4 4. 5 4. 6 wrinkle-of-Sight Transmission 129 Recommended class period and Web Sites 133 paint Terms, recap Questions, and Problems 134 Chapter 5 Signal Encoding Techniques 138 5. 1 digital Data, digital Signals 141 5. 2 Digital Data, Analog Signals 151 5. 3 Analog Data, Digital Signals 162 5. 4 Analog Data, Analog Signals 168 5. 5 Recommended nurture 175 5. 6 list Terms, freshen up Questions, and Problems 175 Chapter 6 Digital Data Communication Techniques 180 6. Asynchronous and Synchronous Transmission 182 6. 2 Types of phantasms 186 6. 3 actus reus Detection 186 6. 4 Error Correction 196 6. 5 Line Configurations 201 6. 6 Recommended Reading 203 6. 7 n otice Terms, shape up off Questions, and Problems 204 Chapter 7 Data affiliate fake Protocols 207 7. 1 Flow Control 209 7. 2 Error Control 216 7. 3 high- take aim Data Link Control (HDLC) 222 7. 4 Recommended Reading 228 7. 5 let on Terms, Review Questions, and Problems 229 vermiform process 7A functioning Issues 232 Chapter 8 Multiplexing 239 8. 1 Frequency-Division Multiplexing 242 8. 2 Synchronous Time-Division Multiplexing 248 8. statistical Time-Division Multiplexing 258 8. 4 Asymmetric Digital Subscriber Line 265 8. 5 xDSL 268 8. 6 Recommended Reading and Web Sites 269 8. 7 Key Terms, Review Questions, and Problems 270 Chapter 9 sp empathise Spectrum 274 9. 1 The Concept of Spread Spectrum 276 9. 2 Frequency Hopping Spread Spectrum 277 9. 3 Direct Sequence Spread Spectrum 282 9. 4 Code-Division Multiple retrieve 287 9. 5 Recommended Reading and Web Site 290 9. 6 Key Terms, Review Questions, and Problems 291 CONTENTS ix PART THREE WIDE bowl NETWORKS 295 Chapter 10 Cir cuit faulting and Packet Switching 297 10. Switched Communications Networks 299 10. 2 Circuit Switching Networks 301 10. 3 Circuit Switching Concepts 304 10. 4 Softswitch Architecture 307 10. 5 Packet-Switching Principles 309 10. 6 X. 25 317 10. 7 Frame electrical relay 319 10. 8 Recommended Reading and Web Sites 324 10. 9 Key Terms, Review Questions, and Problems 325 Chapter 11 Asynchronous Transfer Mode 328 11. 1 Protocol Architecture 329 11. 2 automatic teller machine Logical Connections 331 11. 3 ambience Cells 335 11. 4 Transmission of atm Cells 340 11. 5 ATM attend to Categories 345 11. 6 Recommended Reading and Web Sites 348 11. Key Terms, Review Questions, and Problems 349 Chapter 12 Routing in Switched Networks 351 12. 1 Routing in Packet-Switching Networks 352 12. 2 Examples: Routing in ARPANET 362 12. 3 Least-Cost Algorithms 367 12. 4 Recommended Reading 372 12. 5 Key Terms, Review Questions, and Problems 373 Chapter 13 congestion Control in Data Networks 377 13. 1 Effects of Congestion 379 13. 2 Congestion Control 383 13. 3 occupation prudence 386 13. 4 Congestion Control in Packet-Switching Networks 13. 5 Frame Relay Congestion Control 388 13. 6 ATM Traffic Management 394 13. 7 ATM-GFR Traffic Management 406 13. Recommended Reading 409 13. 9 Key Terms, Review Questions, and Problems 410 Chapter 14 cellular Wireless Networks 413 14. 1 Principles of Cellular Networks 415 14. 2 First genesis Analog 427 14. 3 Second Generation CDMA 429 14. 4 Third Generation dodges 437 14. 5 Recommended Reading and Web Sites 440 14. 6 Key Terms, Review Questions, and Problems 441 387 x CONTENTS PART iv LOCAL AREA NETWORKS 444 Chapter 15 topical anaesthetic commonwealth Network Overview 446 15. 1 Background 448 15. 2 Topologies and Transmission Media 451 15. 3 local area network Protocol Architecture 457 15. 4 Bridges 465 15. 5 work 2 and Layer 3 Switches 473 15. Recommended Reading and Web Site 478 15. 7 Key Terms, Review Questions, and Problems 479 Cha pter 16 High-Speed LANs 482 16. 1 The Emergence of High-Speed LANs 483 16. 2 Ethernet 485 16. 3 grapheme Channel 500 16. 4 Recommended Reading and Web Sites 504 16. 5 Key Terms, Review Questions, and Problems 506 extension 16A Digital Signal Encoding for LANs 508 Appendix 16B capital punishment Issues 514 Appendix 16C Scrambling 518 Chapter 17 Wireless LANs 522 17. 1 Overview 523 17. 2 Wireless LAN engineering 528 17. 3 IEEE 802. 11 Architecture and Services 531 17. 4 IEEE 802. 11 Medium Access Control 535 17. 5 IEEE 802. 1Physical Layer 543 17. 6 IEEE 802. 11 security measure Considerations 549 Recommended Reading and Web Sites 550 17. 7 17. 8 Key Terms, Review Questions, and Problems 551 PART FIVE meshwork AND TRANSPORT PROTOCOLS Chapter 18 Inter net profit Protocols 556 18. 1 Basic Protocol Functions 558 18. 2 Principles of Internetworking 566 18. 3 Internet Protocol surgery 569 18. 4 Internet Protocol 576 18. 5 IPv6 586 18. 6 Virtual Private Networks and IP Security 596 18 . 7 Recommended Reading and Web Sites 599 18. 8 Key Terms, Review Questions, and Problems 600 Chapter 19 Internetwork Operation 603 19. 1 Multicasting 605 19. Routing Protocols 614 19. 3 integrated Services Architecture 625 19. 4 Differentiated Services 636 554 CONTENTS xi 19. 5 19. 6 19. 7 19. 8 Service Level Agreements 645 IP Performance Metrics 646 Recommended Reading and Web Sites 649 Key Terms, Review Questions, and Problems 651 657 Chapter 20 Transport Protocols 655 20. 1 Connection-Oriented Transport Protocol Mechanisms 20. 2 transmission control protocol 674 20. 3 TCP Congestion Control 683 20. 4 UDP 693 20. 5 Recommended Reading and Web Sites 695 Key Terms, Review Questions, and Problems 695 20. 6 PART sise Chapter 21 21. 1 21. 2 21. 3 21. 4 21. 5 21. 6 21. 7 21. 8 21. lucre APPLICATIONS 699 Network Security 701 Security Requirements and Attacks 703 Confidentiality with Conventional encryption 705 Message Authentication and Hash Functions 713 Public-Key Encryption and Di gital Signatures 720 Secure Socket Layer and Transport Layer Security 727 IPv4 and IPv6 Security 732 Wi-Fi Protected Access 737 Recommended Reading and Web Sites 739 Key Terms, Review Questions, and Problems 740 Chapter 22 Internet Applicationsâ€electronic Mail and Network Management 22. 1 electronic Mail: SMTP and MIME 745 22. 2 Network Management: SNMP 760 22. 3 Recommended Reading and Web Sites 770 22. Key Terms, Review Questions, and Problems 771 743 Chapter 23 Internet Applicationsâ€Internet Directory Service and mankind immense Web 23. 1 Internet Directory Service: DNS 774 23. 2 Web Access: HTTP 784 23. 3 Recommended Reading and Web Sites 795 23. 4 Key Terms, Review Questions, and Problems 796 Chapter 24 Internet Applicationsâ€Multimedia 799 24. 1 Audio and tv Compression 800 24. 2 Real-Time Traffic 808 24. 3 Voice Over IP and Multimedia Supportâ€SIP 811 24. 4 Real-Time Transport Protocol (RTP) 820 24. 5 Recommended Reading and Web Sites 831 24. 6 Key Terms, Rev iew Questions, and Problems 832 773 ii CONTENTS APPENDICES 835 Appendix A quadrupleier Analysis 835 A. 1 quadier Series Repre displaceation of hebdomadary Signals 836 A. 2 Fourier Transform Representation of Aperiodic Signals 837 A. 3 Recommended Reading 840 Appendix B Projects for Teaching Data and Computer Communications B. 1 Practical Exercises 842 B. 2 Sockets Projects 843 B. 3 unreal Projects 843 B. 4 Simulation and mold Projects 844 B. 5 Performance regulateing 844 B. 6 Research Projects 845 B. 7 Reading/Report Assignments 845 B. 8 report Assignments 845 B. 9 Discussion Topics 846 References Index 858 ONLINE APPENDICES WilliamStallings. om/DCC Appendix C Sockets: A Programmer’s Introduction C. 1 Versions of Sockets C. 2 Sockets, Socket Descriptors, Ports, and Connections The Client/Server Model of Communication C. 3 C. 4 Sockets Elements C. 5 Stream and Datagram Sockets C. 6 Run-Time Program Control C. 7 Remote executing of a Windows Console Application Appendix D Standards Organizations D. 1 The Importance of Standards D. 2 Standards and Regulation D. 3 Standards-Setting Organizations Appendix E Appendix F The world(prenominal) Reference Alphabet Proof of the Sampling Theorem 847 841 Appendix G Physical-Layer Interfacing G. 1 V. 24/EIA-232-F G. ISDN Physical interface Appendix H The OSI Model H. 1 The Model H. 2 The OSI Layers CONTENTS xiii Appendix I Queuing Effects I. 1 Queuing Models I. 2 Queuing Results Appendix J Orthogonality, Correlation, and Autocorrelation J. 1 Correlation and Autocorrelation J. 2 Orthogonal Codes Appendix K The TCP/IP Checksum K. 1 unitys-Complement growth K. 2 Use in TCP and IP Appendix L TCP/IP Example Appendix M supply Resource locators (URLs) and Uniform Resource Identifiers (URIs) M. 1 Uniform Resource Locator M. 2 Uniform Resource Identifier M. 3 To watch More Appendix N Glossary increase Backus-Naur FormThis page intentionally left blank warm-up Begin at the arising and go on till you come to the end; then stop. â€Alice in Wonderland, Lewis Carroll OBJECTIVES This apply attempts to provide a unified overview of the abundant report of selective information and information treat administration communications. The organization of the platter reflects an attempt to break this massive subject into clear part and to build, rig by piece, a st be of the state of the art. The book emphasizes basic principles and topics of central vastness concerning the engineering science and architecture of this line of barter and provides a dilate discussion of leading-edge topics.The future(a) basic themes serve to commingle the discussion: • Principles: Although the stage setting of this book is broad, at that place argon a number of basic principles that appear repeatedly as themes and that unify this field. Examples ar two-foldxing, flow control, and error control. The book high crystallises these principles and contrasts their natural covering in proper(pos tnominal) argonas of technology. • Design firees: The book examines alternative approaches to gibeing specific communication requirements. • Standards: Standards afford come to assume an change magnitudely serious, then dominant, role in this field.An understanding of the current emplacement and future direction of technology requires a nation grand discussion of the colligated standards. INTENDED AUDIENCE The book is intended for twain an academic and a headmaster audience. For the professional interested in this field, the book serves as a basic reference volume and is suitable for self-study. As a textbook, it can be employ for a genius-semester or two-semester execute. It covers the material in Networking (NET), a core argona in the Information Technology body of knowledge, which is part of the Draft ACM/IEEE/AIS Computing Curricula 2005.The book likewise covers the material in Computer Networks (CE-NWK), a core sector in Computer introduction 2004 Curriculum Guidelines from the ACM/IEEE Joint Task Force on Computing Curricula. PLAN OF THE TEXT The book is dual-lane into six parts (see Chapter 0): • Overview • Data Communications • Wide scene of action Networks xv xvi PREFACE • Local Area Networks • Internet and Transport Protocols • Internet Applications In adjunct, the book includes an extensive glossary, a list of oftentimes use acronyms, and a bibliography. Each chapter includes problems and suggestions for further practice session.The chapters and parts of the book ar sufficiently modular to provide a great deal of flexibility in the radiation draw of courses. See Chapter 0 for a number of detailed suggestions for twain(prenominal) top-down and bottom-up course strategies. INSTRUCTIONAL SUPPORT MATERIALS To support instructors, the following materials are provided: • Solutions Manual: Solutions to all end-of-chapter Review Questions and Problems. • PowerPoint Slid es: A notice of slides covering all chapters, suitable for use in lecturing. • PDF turn ons: Reproductions of all figures and tables from the book. Projects Manual: Suggested give assignments for all of the project categories listed below. Instructors may contact their Pearson Education or Prentice Hall representative for access to these materials. In addition, the book’s Web site supports instructors with: • Links to Webs sites for other courses being taught using this book • Sign up information for an Internet mailing list for instructors meshing SERVICES FOR instructorS AND STUDENTS at that place is a Web site for this book that provides support for students and instructors.The site includes links to other relevant sites, transparency masters of figures in the book, and sign-up information for the book’s Internet mailing list. The Web page is at WilliamStallings. com/DCC/DCC8e. html; see the section, Web Site for Data and Computer Communicati ons, preceding the prorogue of Contents, for to a greater extent information. An Internet mailing list has been set up so that instructors using this book can exchange information, suggestions, and questions with each other and with the author. As short as typos or other errors are discover, an errata list for this book will be roaring at WilliamStallings. om. PROJECTS AND OTHER STUDENT EXERCISES For many a(prenominal) instructors, an chief(prenominal) lot of a selective information communications or networking course is a project or set of projects by which the student gets hands-on accept to reinforce concepts from the text. This book provides an unparalleled degree of support for including a projects percentage in the course. The instructor’s addendum not only includes guidance on how to assign and expression the projects yet also includes a set of user’s PREFACE xvii Manuals for various project types incontrovertible specific assignments, all written oddly for this book.Instructors can assign work in the following realms: • Practical exercises: Using network commands, the student gains endure in network connectivity. • Sockets programming projects: The book is support by a detailed description of Sockets available at the book’s Web site. The Instructors accessary includes a set of programming projects. Sockets programming is an â€Å"easy” topic and one that can result in very satisfying hands-on projects for students. • Ethereal projects: Ethereal is a protocol analyzer that enables students to study the look of protocols. Simulation projects: The student can use the feigning package cnet to analyze network behavior. • Performance instanceing projects: 2 performance homunculusing techniques are provided a tools package and OPNET. • Research projects: The instructor’s supplement includes a list of suggested research projects that would involve Web and literature search es. • Reading/report assignments: The instructor’s supplement includes a list of papers that can be assigned for reading and writing a report, plus suggested assignment wording. Writing assignments: The instructor’s supplement includes a list of writing assignments to drive on learning the material. • Discussion topics: These topics can be used in a classroom, chat room, or subject matter board environment to explore true subjects in greater depth and to foster student collaboration. This divers(prenominal) set of projects and other student exercises enables the instructor to use the book as one component in a rich and varied learning experience and to tailor a course plan to meet the specific indigences of the instructor and students. See Appendix B for details.WHAT’S NEW IN THE EIGHTH EDITION This eighth edition is seeing the light of day less than four years by and by the commonplaceation of the ordinal edition. During that time, the pace of change in this field continues unabated. In this new edition, I savour to capture these changes patch maintaining a broad and all-around(prenominal) reporting of the entire field. To begin the process of revision, the seventh edition of this book was extensively reviewed by a number of professors who teach the subject. The result is that, in many places, the narrative has been clarified and tightened, and illustrations hold up been improved.Also, a number of new â€Å"field-tested” problems have been added. Beyond these refinements to improve pedagogy and user friendliness, there have been major solid changes byout the book. Every chapter has been revised, new chapters have been added, and the general organization of the book has changed. Highlights include: • Updated reportage of Giga endorsement Ethernet and 10-Gbps Ethernet: New details of these standards are provided. • Updated reporting of WiFi/IEEE 802. 11 radio LANs: IEEE 802. 11 and the relat ed WiFi specifications have continued to evolve. viii PREFACE • New coverage of IP performance metrics and service level agreements (SLAs): These aspects of Quality of Service (QoS) and performance monitoring are increasingly important. • Address Resolution Protocol (ARP): This important protocol is now covered. • New coverage of TCP Tahoe, Reno, and NewReno: These congestion control algorithms are now common in nearly moneymaking(prenominal) implementations. • Expanded coverage of security: Chapter 21 is much than detailed; other chapters provide overview of security for the relevant topic.Among the new topics are Wi-Fi Protected Access (WPA) and the secure hash algorithm SHA-512. • Domain Name System (DNS): This important end is now covered. • New coverage of multimedia: antecedent section in Chapter 2; detailed coverage in Chapter 24. Topics covered include video compression, SIP, and RTP. • Online appendices: cardinal online appe ndices provide additional detail on important topics in the text, including Sockets programming, queuing models, the Internet checksum, a detailed prototype of TCP/IP operation, and the BNF grammar.In addition, throughout the book, or so close to(prenominal) topic has been updated to reflect the developments in standards and technology that have occurred since the earthly concernation of the seventh edition. ACKNOWLEDGMENTS This new edition has benefited from review by a number of pile, who gave generously of their time and expertise. The following people reviewed all or a large part of the manuscript: Xin Liu- (UC, Davis), Jorge Cobb, Andras Farago, Dr. Prasant Mohapatra (UC Davis), Dr. Jingxian Wu (Sonoma State University), G. R.Dattareya (UT Dallas), Guanling subgenus Chen (Umass, Lowell), Bob Roohaprvar (Cal State eastbound Bay), Ahmed Banafa (Cal State East Bay), Ching-Chen Lee (CSU Hayward), and Daji Qaio (Iowa State). Thanks also to the many people who provided detail ed technical reviews of a single chapter: Dave Tweed, Bruce Lane, Denis McMahon, Charles Freund, Paul Hoadley, Stephen Ma, Sandeep Subramaniam, Dragan Cvetkovic, Fernando Gont, Neil Giles, Rajesh Thundil, and Rick Jones. In addition, Larry Owens of California State University and Katia Obraczka of the University of gray California provided about homework problems.Thanks also to the following contri furtherors. Zornitza Prodanoff of the University of North Florida prepared the appendix on Sockets programming. Michael Harris of the University of southern Florida is responsible for the Ethereal exercises and user’s guide. Lawrie brownish of the Australian Defence Force Academy of the University of New South Wales produced the PPT lecture slides. Finally, I would like to give thanks the many people responsible for the publication of the book, all of whom did their usual excellent pipeline.This includes the staff at Prentice Hall, particularly my editor Tracy Dunkelberger, h er assistants Christianna Lee and Carole Snyder, and production manager Rose Kernan. Also, Patricia M. Daly did the facsimile editing. CHAPTER contri stillor’S AND teacher’S GUIDE 0. 1 0. 2 0. 3 0. 4 Outline of the Book Roadmap Internet and Web Resources Standards 0 1 2 CHAPTER 0 / READER’S AND INSTRUCTOR’S GUIDE â€Å"In the meanwhile, then,” acquireed Li-loe, â€Å"relate to me the story to which reference has been made, thereby proving the justness of your assertion, and at the kindred time affording n sport of a slightlywhat exceptional kind. ” â€Å"The shadows lengthen,” replied Kai Lung, â€Å"but as the narrative in question is of an inconspicuous suspender I will raise no bulwark against your flattering request, especially as it indicates an awakening penchant hitherto unexpected. ” â€Kai Lung’s Golden Hours, Earnest Bramah This book, with its ac ships companying Web site, covers a lot of material. Here we give the reader some basic background information. 0. 1 OUTLINE OF THE BOOK The book is organize into five parts: objet dart peerless. Overview: Provides an introduction to the range of topics covered in the book.This part includes a general overview of entropy communications and networking and a discussion of protocols, OSI, and the TCP/IP protocol retinue. sectionalisation Two. Data Communications: bear on to begin with with the exchange of entropy between two directly connected devices. Within this restricted scope, the spot aspects of transmission, interfacing, link control, and multiplexing are examined. section cardinal. Wide Area Networks: Examines the ingrained mechanisms and user-network interfaces that have been necessary to support division, selective information, and multimedia communications over long distance networks.The traditional technologies of bundle switching and circuit switching are examined, as well as the to a greater extent new- fashioned ATM and wireless WANs. Separate chapters are devoted to routing and congestion control issues that are relevant twain to switched info networks and to the Internet. blow up Four. Local Area Networks: Explores the technologies and architectures that have been developed for networking over shorter distances. The transmission media, topologies, and medium access control protocols that are the reveal ingredients of a LAN design are explored and specific standardized LAN frames examined. farewell Five. Networking Protocols: Explores both(prenominal) the architectural principles and the mechanisms required for the exchange of selective information among computing machines, workstations, hordes, and other selective information processing devices. Much of the material in this part relates to the TCP/IP protocol suite. Part Six. Internet Applications: Looks at a range of performances that wage over the Internet. A more detailed, chapter-by-chapter summary of each part a ppears at the ascendant of that part. 0. 2 / ROADMAP 3 0. 2 ROADMAP Course EmphasisThe material in this book is organized into four broad categories: data transmission and communication; communications networks; network protocols; and applications and security. The chapters and parts of the book are sufficiently modular to provide a great deal of flexibility in the design of courses. The following are suggestions for terzetto different course designs: • Fundamentals of Data Communications: separate unity (overview) and Two (data communications) and Chapters 10 and 11 (circuit switching, packet switching, and ATM). Communications Networks: If the student has a basic background in data communications, then this course could cover split wholeness (overview), threesome (WAN), and Four (LAN). • Computer Networks: If the student has a basic background in data communications, then this course could cover Part One (overview), Chapters 6 and 7 (data communication techniques and data link control), Part Five (protocols), and part or all of Part Six (applications). In addition, a more streamlined course that covers the entire book is thinkable by eliminating certain chapters that are not essential on a for the first time reading.Chapters that could be elective are Chapters 3 (data transmission) and 4 (transmission media), if the student has a basic understanding of these topics; Chapter 8 (multiplexing); Chapter 9 (spread spectrum); Chapters 12 through 14 (routing, congestion control, cellular networks); Chapter 18 (internetworking); and Chapter 21 (network security). Bottom-Up versus Top-Down The book is organized in a modular fashion. afterwards reading Part One, the other parts can be read in a number of feasible sequences. human body 0. 1a shows the bottom-up approach provided by reading the book from front to back. With this approach, each part builds on the material in the previous part, so that it is always overhaul how a given mold of fun ctionality is supported from below. There is more material than can be substantially covered in a single semester, but the book’s organization makes it easy to scorn some chapters and maintain the bottom-up sequence. realise 0. 1b suggests one approach to a check course.Some readers, and some instructors, are more comfortable with a top-down approach. After the background material (Part One), the reader continues at the application level and works down through the protocol layers. This has the advantage of immediately focusing on the or so visible part of the material, the applications, and then seeing, progressively, how each layer is supported by the next layer down. betoken 0. 1c is an example of a comprehensive treatment and skeleton 0. 1d is an example of a check into treatment. 4 CHAPTER 0 / READER’S AND INSTRUCTOR’S GUIDEPart One Overview Part Two Data Communications Part Three Wide Area Networks Part Four Local Area Networks Part Five Internet an d Transport Protocols Part Six Internet Applications (a) A bottom-up approach Part One Overview Chapter 18 The Internet Protocol Part Six Internet Applications Part Five TCP/IP Part Three WANs Part Four LANs Part Two Data Communications (c) A top-down approach (d) Another top-down approach (b) Another bottom-up approach Part One Overview Chapter 18 The Internet Protocol Part Six Internet Applications Part Five TCP/IP Part Three WANs (10, 12) Part Four LANs (15) Part One Overview (1, 2) Part Two Data Communications (3, 6, 7, 8) Part Three WANs (10, 12) Part Four LANs (15) Part Five TCP/IP (18, 20) Figure 0. 1 Suggested Reading Orders Finally, it is mathematical to select chapters to reflect specific teaching headings by not sticking to a strict chapter ordering. We give two examples used in courses taught with the seventh edition.One course used the sequence Part One (Overview); Chapter 3 (Data Transmission); Chapter 6 (Digital Data Communications Techniques); Chapter 7 (Data Link Control); Chapter 15 (LAN Overview); Chapter 16 (High-Speed LANs); Chapter 10 (Circuit and Packet Switching); Chapter 12 (Routing); Chapter 18 (Internet Protocols); and Chapter 19 (Internet Operation). The other course used the sequence Part One (Overview); Chapter 3 (Data Transmission); Chapter 4 (Guided and Wireless Transmission); Chapter 5 (Signal Encoding Techniques); Chapter 8 (Multiplexing); Chapter 15 (LAN 0. 3 / mesh AND WEB RESOURCES 5 Overview); Chapter 16 (High-Speed LANs); Chapter 10 (Circuit and Packet Switching); Chapter 20 (Transport Protocols); Chapter 18 (Internet Protocols); and Chapter 19 (Internet Operation). 0. 3 meshing AND WEB RESOURCES There are a number of resources available on the Internet and the Web to support this book and to help one keep up with developments in this field.Web Sites for This Book A special Web page has been set up for this book at WilliamStallings. com/DCC/ DCC8e. html. See the two-page layout at the beginning of this book for a deta iled description of that site. As soon as any typos or other errors are discovered, an errata list for this book will be available at the Web site. Please report any errors that you spot. Errata sheets for my other books are at WilliamStallings. com. I also maintain the Computer Science Student Resource Site, at WilliamStallings. com/StudentSupport. html. The purpose of this site is to provide documents, information, and links for figurer science students and professionals.Links and documents are organized into four categories: • Math: Includes a basic math refresher, a queuing analysis primer, a number ashes primer, and links to numerous math sites • How-to: Advice and guidance for resolving power homework problems, writing technical reports, and preparing technical presentations • Research resources: Links to important collections of papers, technical reports, and bibliographies • Miscellaneous: A medley of useful documents and links Other Web Sites Ther e are numerous Web sites that provide information related to the topics of this book. In subsequent chapters, pointers to specific Web sites can be found in the Recommended Reading and Web Sites section. Because the addresses for Web sites tend to change frequently, I have not included URLs in the book. For all of the Web sites listed in the book, the appropriate link can be found at this book’s Web site. Other links not mentioned in this book will be added to the Web site over time.The following are Web sites of general interest related to data and computer communications: • Network World: Information and links to resources about data communications and networking. • IETF: Maintains archives that relate to the Internet and IETF activities. Includes keyword-indexed library of RFCs and draft documents as well as many other documents related to the Internet and related protocols. 6 CHAPTER 0 / READER’S AND INSTRUCTOR’S GUIDE • Vendors: Links to t housands of ironware and software vendors who soon have Web sites, as well as a list of thousands of computer and networking companies in a phone directory. • IEEE Communications golf club: Good way to keep up on conferences, publications, and so on. ACM Special Interest Group on Communications (SIGCOMM): Good way to keep up on conferences, publications, and so on. • transnational Telecommunications aggregate: Contains a listing of ITU-T recommendations, plus information on obtaining ITU-T documents in hard copy or on videodisk. • International Organization for Standardization: Contains a listing of ISO standards, plus information on obtaining ISO documents in hard copy or on CD-ROM. • CommWeb: Links to vendors, tutorials, and other useful information. • CommsDesign: Lot of useful articles, tutorials, and product information. A grab hard to navigate, but worthwhile. USENET Newsgroups A number of USENET newsgroups are devoted to some aspect of dat a communications, networks, and protocols.As with realisticly all USENET groups, there is a high noise-to-signal ratio, but it is worth experimenting to see if any meet your needs. The more or less relevant are as follows: • comp. dcom. lans, comp. dcom. lans. misc: General discussions of LANs • comp. dcom. lans. ethernet: Covers Ethernet, Ethernet-like governances, and the IEEE 802. 3 CSMA/CD standards • comp. std. wireless: General discussion of wireless networks, including wireless LANs • comp. security. misc: Computer security and encryption • comp. dcom. cell-relay: Covers ATM and ATM LANs • comp. dcom. frame-relay: Covers frame relay networks • comp. dcom. net- anxiety: Discussion of network caution applications, protocols, and standards • comp. rotocols. tcp-ip: The TCP/IP protocol suite 0. 4 STANDARDS It has long been accepted in the telecommunications diligence that standards are required to govern the visible, electric al, and procedural characteristics of communication equipment. In the past, this view has not been embraced by the computer industry. Whereas communication equipment vendors recognize that their 0. 4 / STANDARDS 7 equipment will generally interface to and give out with other vendors’ equipment, computer vendors have traditionally attempted to monopolize their customers. The proliferation of computers and distributed processing has made that an untenable position.Computers from different vendors essentialiness communicate with each other and, with the ongoing evolution of protocol standards, customers will no longer accept special-purpose protocol renascence software development. The result is that standards now dawn all of the areas of technology discussed in this book. There are a number of advantages and disadvantages to the standards-making process. We list here the or so striking ones. The principal advantages of standards are as follows: • A standard assures that there will be a large market for a particular piece of equipment or software. This encourages mass production and, in some cases, the use of large-scale-integration (LSI) or very-large-scale-integration (VLSI) techniques, resulting in lower costs. A standard allows products from multiple vendors to communicate, giving the purchaser more flexibility in equipment selection and use. The principal disadvantages are as follows: • A standard tends to freeze the technology. By the time a standard is developed, subjected to review and compromise, and promulgated, more efficient techniques are possible. • There are multiple standards for the same thing. This is not a disadvantage of standards per se, but of the current way things are done. Fortunately, in fresh years the various standards-making organizations have begun to cooperate more closely. N ever sotheless, there are still areas where multiple strange standards exist.Throughout this book, we describe the close to important standards in use or being developed for various aspects of data and computer communications. Various organizations have been involved in the development or promotion of these standards. The following are the around important (in the current context) of these organizations: • Internet participation: The Internet SOCiety (ISOC) is a professional membership society with more than 150 organisational and 6000 single(a) members in over 100 countries. It provides leadership in addressing issues that confront the future of the Internet and is the organization home for the groups responsible for Internet infrastructure standards, including the Internet engineering science Task Force (IETF) and the Internet Architecture add-in (IAB).All of the RFCs and Internet standards are developed through these organizations. • IEEE 802: The IEEE (Institute of galvanic and Electronics Engineers) 802 LAN/MAN Standards Committee develops local area network standards and metropol itan area network standards. The most greatly used standards are for the Ethernet family, wireless LAN, bridging, and virtual bridged LANs. An individual working group provides the focus for each area. 8 CHAPTER 0 / READER’S AND INSTRUCTOR’S GUIDE • ITU-T: The International Telecommunication Union (ITU) is an world-wide organization within the United Nations System where governments and the private sector coordinate global telecom networks and services.The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors of the ITU. ITU-T’s mission is the production of standards covering all fields of telecommunications. • ATM fabrication: The ATM fabrication is an international nonprofit organization form with the objective of accelerating the use of ATM (asynchronous transfer mode) products and services through a rapid convergence of interoper king specifications. In addition, the Forum promotes industry cooperation and awareness . • ISO: The International Organization for Standardization (ISO)1 is a worldwide federation of national standards bodies from more than one hundred forty countries, one from each country.ISO is a nongovernmental organization that promotes the development of standardization and related activities with a view to facilitating the international exchange of goods and services, and to developing cooperation in the spheres of intellectual, scientific, technological, and economic activity. ISO’s work results in international agreements that are promulgated as International Standards. A more detailed discussion of these organizations is contained in Appendix D. 1 ISO is not an acronym (in which case it would be IOS), but a word, derived from the Greek, sum equal. PART ONE Overview The purpose of Part One is to provide a background and context for the lowest of this book. The broad range of topics that are encompassed in the field of data and computer communications is introd uced, and the fundamental concepts of protocols and protocol architectures are examined.ROAD MAP FOR PART ONE Chapter 1 Data Communications, Data Networks, and The Internet Chapter 1 provides an overview of hold out Two through Four of the book, giving the â€Å" rangy limn. ” In essence, the book deals with four topics: data communications over a transmission link; wide area networks; local area networks; and protocols and the TCP/IP protocol architecture. Chapter 1 provides a preview of the first three of these topics. Chapter 2 Protocol Architecture, TCP/IP, and Internet-Based Applications Chapter 2 discusses the concept protocol architectures. This chapter can be read immediately following Chapter 1 or deferred until the beginning of Part Three, Four, or Five.After a general introduction, the chapter deals with the two most important protocol architectures: the Open Systems interconnection (OSI) model and TCP/IP. Although the OSI model is often used as the framework for discourse in this area, it is the TCP/IP protocol suite that is the basis for most commercially available interoperable products and that is the focus of Parts Five and Six of this book. 9 CHAPTER DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET 1. 1 1. 2 1. 3 1. 4 1. 5 1. 6 Data Communications and Networking for Today’s Enterprise A Communications Model Data Communications Networks The Internet An Example Configuration 1 10 The fundamental problem of communication is that of reproducing at one point either hardly or approximately a message selected at another point. The Mathematical Theory of Communication, Claude Shannon KEY POINTS • The scope of this book is broad, covering three general areas: data communications, networking, and protocols; the first two are introduced in this chapter. Data communications deals with the transmission of signals in a dependable and efficient manner. Topics covered include signal transmission, transmission media, signal encod ing, interfacing, data link control, and multiplexing. Networking deals with the technology and architecture of the communications networks used to interconnect communicating devices. This field is generally divided into the topics of local area networks (LANs) and wide area networks (WANs). • •The 1970s and eighties saw a merger of the fields of computer science and data communications that profoundly changed the technology, products, and companies of the now combined computer-communications industry. The computercommunications novelty has produced several remarkable facts: • There is no fundamental difference between data processing (computers) and data communications (transmission and switching equipment). • There are no fundamental differences among data, voice, and video communications. • The distinction among single-processor computer, multiprocessor computer, local network, metropolitan network, and long-haul network has blurred.One effect of th ese styles has been a growing coincide of the computer and communications industries, from component fabrication to system integration. Another result is the development of integrated systems that transmit and process all types of data and information. Both the technology and the technical standards organizations are cause toward integrated public systems that make virtually all data and information sources around the world easily and uniformly accessible. This book aims to provide a unified view of the broad field of data and computer communications. The organization of the book reflects an attempt to break this massive subject into comprehensible parts and to build, piece by piece, a survey of the state of the art.This introductory chapter begins with a general model of communications. past a brief discussion introduces each of the Parts Two through Four of this book. Chapter 2 provides an overview to Parts Five and Six 11 12 CHAPTER 1 / DATA COMMUNICATIONS, DATA NETWORKS, AN D THE INTERNET 1. 1 DATA COMMUNICATIONS AND NETWORKING FOR TODAY’S go-ahead Effective and efficient data communication and networking facilities are vital to any attempt. In this section, we first look at trends that are increasing the challenge for the business manager in planning and managing much(prenominal)(prenominal) facilities. Then we look specifically at the requirement for ever-greater transmission recreates and network mental ability. TrendsThree different forces have lie inently operate the architecture and evolution of data communications and networking facilities: dealings growth, development of new services, and advances in technology. Communication affair, both local (within a building or building complex) and long distance, both voice and data, has been growing at a high and steady rate for decades. The increasing strain on blot automation, remote access, online transactions, and other productivity measures means that this trend is likely to continue. Thus, managers are constantly struggling to maximize capacity and downplay transmission costs. As businesses rely more and more on information technology, the range of services expands. This increases the assume for high-capacity networking and transmission facilities.In turn, the continuing growth in high-velocity network offerings with the continuing drop in prices encourages the elaboration of services. Thus, growth in services and growth in calling capacity go hand in hand. Figure 1. 1 gives some examples of information-based services and the data rates inevitable to support them [ELSA02]. Finally, trends in technology enable the provision of increasing traffic capacity and the support of a wide range of services. Four technology trends are particularly notable: 1. The trend toward faster and cheaper, both in computing and communications, continues. In terms of computing, this means more powerful computers and clusters of computers equal of supporting more demanding applic ations, much(prenominal) as multimedia applications.In terms of communications, the increasing use of optical fictitious character has brought transmission prices down and greatly change magnitude capacity. For example, for long-distance telecommunication and data network links, recent offerings of gruelling wavelength division multiplexing (DWDM) enable capacities of many terabits per second. For local area networks (LANs) many enterprises now have Gigabit Ethernet backbone networks and some are beginning to deploy 10-Gbps Ethernet. 2. Both voice-oriented telecommunications networks, much(prenominal) as the public switched telephone set network (PSTN), and data networks, including the Internet, are more â€Å"intelligent” than ever. Two areas of intelligence are singular.First, today’s networks can offer differing levels of quality of service (QoS), which include specifications for maximum find out, stripped-down throughput, and so on. Second, today’s networks provide a variety of customizable services in the areas of network management and security. 1. 1 / DATA COMMUNICATIONS AND NETWORKING FOR TODAY’S ENTERPRISE Speed (kbps) Transaction processing electronic messaging/text apps Voice Location services politic build transfers Internet/VPN access Database access intensify Web surfing Low-quality video Hifi audio overlarge file transfer Moderate video synergistic entertainment High-quality video Performance: Poor adequate to(predicate) Good 9. 6 14. 4 28 64 144 384 2000 13 VPN: virtual private network Figure 1. 1 Services versus Throughput Rates 3.The Internet, the Web, and associated applications have emerged as dominant features of both the business and ad hominem world, opening up many opportunities and challenges for managers. In addition to exploiting the Internet and the Web to reach customers, suppliers, and partners, enterprises have formed intranets and extranets1 to isolate their proprietary information fr ee from outcast access. 4. There has been a trend toward ever-increasing mobility for decades, liberating workers from the confines of the physical enterprise. Innovations include voice mail, remote data access, pagers, fax, e-mail, cordless phones, cell phones and cellular networks, and Internet portals.The result is the ability of employees to take their business context with them as they move about. We are now seeing the growth of high-speed wireless access, which further enhances the ability to use enterprise information resources and services anywhere. 1 Briefly, an intranet uses Internet and Web technology in an isolated facility internal to an enterprise; an extranet extends a company’s intranet out onto the Internet to allow selected customers, suppliers, and mobile workers to access the company’s private data and applications. 14 CHAPTER 1 / DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET Data Transmission and Network Capacity RequirementsMomentous chang es in the way organizations do business and process information have been drive by changes in networking technology and at the same time have driven those changes. It is hard to separate chicken and egg in this field. Similarly, the use of the Internet by both businesses and individuals reflects this cyclic dependency: the availability of new discover-based services on the Internet (i. e. , the Web) has resulted in an increase in the entireness number of users and the traffic volume generated by each user. This, in turn, has resulted in a need to increase the speed and expertness of the Internet. On the other hand, it is only such increased speed that makes the use of Web-based applications palatable to the end user.In this section, we survey some of the end-user factors that fit into this equation. We begin with the need for high-speed LANs in the business environment, because this need has appeared first and has forced the pace of networking development. Then we look at busi ness WAN requirements. Finally we offer a hardly a(prenominal) words about the effect of changes in commercial electronics on network requirements. The Emergence of High-Speed LANs personalised computers and microcomputer workstations began to achieve widespread acceptance in business computing in the early 1980s and have now achieved virtually the status of the telephone: an essential tool for office workers.Until relatively recently, office LANs provided basic connectivity servicesâ€connecting personal computers and terminals to mainframes and midrange systems that ran corporeal applications, and providing workgroup connectivity at the departmental or divisional level. In both cases, traffic patterns were relatively light, with an emphasis on file transfer and electronic mail. The LANs that were available for this type of workload, primarily Ethernet and minimum ring, are well suited to this environment. In the 1990s, two significant trends altered the role of the personal computer and therefore the requirements on the LAN: 1. The speed and computing power of personal computers continued to extol explosive growth. These more powerful platforms support graphics-intensive applications and ever more elaborate graphical user interfaces to the in operation(p) system. . MIS (management information systems) organizations have recognized the LAN as a viable and essential computing platform, resulting in the focus on network computing. This trend began with guest/server computing, which has capture a dominant architecture in the business environment and the more recent Webfocused intranet trend. Both of these approaches involve the frequent transfer of potentially large volumes of data in a transaction-oriented environment. The effect of these trends has been to increase the volume of data to be handled over LANs and, because applications are more interactive, to reduce the acceptable delay on data transfers.The earlier generation of 10-Mbps Ethernets and 1 6-Mbps token rings was simply not up to the job of supporting these requirements. The following are examples of requirements that call for higher-speed LANs: • centralise server farms: In many applications, there is a need for user, or client, systems to be able to stool huge amounts of data from multiple change servers, called server farms. An example is a color publishing operation, in 1. 1 / DATA COMMUNICATIONS AND NETWORKING FOR TODAY’S ENTERPRISE 15 which servers naturally contain tens of gigabytes of image data that must be downloaded to imaging workstations. As the performance of the servers themselves has increased, the bottleneck has shifted to the network. Power workgroups: These groups typically consist of a small number of cooperating users who need to key out massive data files across the network. Examples are a software development group that runs tests on a new software version, or a computer-aided design (CAD) company that regularly runs simulations of new designs. In such cases, large amounts of data are distributed to several workstations, processed, and updated at very high speed for multiple iterations. • high-velocity local backbone: As processing demand grows, LANs proliferate at a site, and high-speed interconnection is necessary. Corporate Wide Area Networking Needs As recently as the early 1990s, there was an emphasis in many organizations on a modify data processing model.In a typical environment, there might be significant computing facilities at a fewer regional offices, consisting of mainframes or well-equipped midrange systems. These centralized facilities could handle most corporate applications, including basic finance, accounting, and personnel department programs, as well as many of the business-specific applications. Smaller, far offices (e. g. , a bank branch) could be equipped with terminals or basic personal computers linked to one of the regional centers in a transaction-oriented environment. T his model began to change in the early 1990s, and the change accelerated through the mid-1990s. many another(prenominal) organizations have dispersed their employees into multiple smaller offices.There is a growing use of telecommuting. Most significant, the nature of the application structure has changed. First client/server computing and, more recently, intranet computing have fundamentally restructured the organizational data processing environment. There is now much more reliance on personal computers, workstations, and servers and much less use of centralized mainframe and midrange systems. Furthermore, the virtually universal deployment of graphical user interfaces to the desktop enables the end user to exploit graphic applications, multimedia, and other data-intensive applications. In addition, most organizations require access to the Internet.When a few clicks of the mouse can trigger huge volumes of data, traffic patterns have become more unpredictable while the average lo ad has risen. All of these trends means that more data must be transported off premise and into the wide area. It has long been accepted that in the typical business environment, about 80% of the traffic dust local and about 20% traverses wide area links. But this rule no longer applies to most companies, with a greater percentage of the traffic going into the WAN environment [COHE96]. This traffic flow shift places a greater burden on LAN backbones and, of course, on the WAN facilities used by a corporation.Thus, just as in the local area, changes in corporate data traffic patterns are driving the creation of high-speed WANs. Digital Electronics The rapid conversion of consumer electronics to digital technology is having an impact on both the Internet and corporate intranets. As these new gadgets come into view and proliferate, they dramatically increase the amount of image and video traffic carried by networks. Two noteworthy examples of this trend are digital versatile disks (DV Ds) and digital still cameras. With the capacious DVD, the electronics industry has at last 16 CHAPTER 1 / DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET found an acceptable replacement for the analogue VHS videotape.The DVD has replaced the videotape used in videocassette recorders (VCRs) and replaced the CD-ROM in personal computers and servers. The DVD takes video into the digital age. It delivers movies with picture quality that outshines laser disks, and it can be indiscriminately accessed like audio CDs, which DVD machines can also play. Vast volumes of data can be crammed onto the disk, currently seven times as much as a CDROM. With DVD’s huge depot capacity and vivid quality, PC games have become more realistic and educational software incorporates more video. Following in the wake of these developments is a new crest of traffic over the Internet and corporate intranets, as this material is incorporated into Web sites. A related product development is the digi tal camcorder.This product has made it easier for individuals and companies to make digital video files to be placed on corporate and Internet Web sites, again adding to the traffic burden. 1. 2 A COMMUNICATIONS MODEL This section introduces a sincere model of communications, illustrated by the block diagram in Figure 1. 2a. The fundamental purpose of a communications system is the exchange of data between two parties. Figure 1. 2b presents one particular example, which is communication between a workstation and a server over a public telephone network. Another example is the exchange of voice signals between two telephones over the same network. The key elements of the model are as follows: • stem.This device generates the data to be transmitted; examples are telephones and personal computers. Source system Destination system Source vector Transmission System (a) General block diagram Receiver Destination Workstation Modem Public telephone network (b) Example Modem Server Figure 1. 2 simplified Communications Model 1. 2 / A COMMUNICATIONS MODEL 17 • Transmitter: Usually, the data generated by a source system are not transmitted directly in the form in which they were generated. Rather, a transmitter transforms and encodes the information in such a way as to produce electromagnetic signals that can be transmitted across some sort of transmission system.For example, a modem takes a digital bit stream from an attached device such as a personal computer and transforms that bit stream into an analog signal that can be handled by the telephone network. • Transmission system: This can be a single transmission line or a complex network connecting source and destination. • Receiver: The receiver accepts the signal from the transmission system and converts it into a form that can be handled by the destination device. For example, a modem will accept an analog signal coming from a network or transmission line and convert it into a digital bit stream. • Destination: Takes the incoming data from the receiver.This simple narrative conceals a wealth of technical complexity. To get some idea of the scope of this complexity, Table 1. 1 lists some of the key tasks that must be performed in a data communications system. The list is approximately arbitrary: Elements could be added; items on the list could be merged; and some items represent several tasks that are performed at different â€Å"levels” of the system. However, the list as it stands is indicative of the scope of this book. The first item, transmission system utilization, refers to the need to make efficient use of transmission facilities that are typically shared among a number of communicating devices.Various techniques (referred to as multiplexing) are used to allocate the total capacity of a transmission medium among a number of users. Congestion control techniques may be required to assure that the system is not overwhelmed by excessive demand for transmission services. To communicate, a device must interface with the transmission system. All the forms of communication discussed in this book depend on the use of electromagnetic signals propagated over a transmission medium. Thus, once an interface is established, signal generation is required for communication. The properties of the signal, such as form and intensity, must be such that the signal is (1) capable of being propagated through the transmission system, and (2) interpretable as data at the receiver.Not only must the signals be generated to conform to the requirements of the transmission system and receiver, but also there must be some form of synchronization Table 1. 1 Communications Tasks Transmission system utilization Interfacing Signal generation Synchronization Exchange management Error detection and correction Flow control Addressing Routing recuperation Message formatting Security Network management 18 CHAPTER 1 / DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET between transmitter and receiver. The receiver must be able to determine when a signal begins to draw in and when it ends. It must also know the duration of each signal element.Beyond the basic matter of deciding on the nature and timing of signals, there is a variety of requirements for communication between two parties that might be collected under the term exchange management. If data are to be exchanged in both directions over a period of time, the two parties must cooperate. For example, for two parties to engage in a telephone conversation, one party must dial the number of the other, causing signals to be generated that result in the plangency of the called phone. The called party completes a connection by lifting the receiver. For data processing devices, more will be needed than simply establishing a connection; certain conventions must be decided on.These conventions may include whether both devices may transmit simultaneously or must take turns, the amount of d ata to be sent at one time, the format of the data, and what to do if certain contingencies such as an error arise. The next two items might have been included under exchange managem\r\n'

'Western Union\r'

' horse opera coalescence was founded in 1851 and dieed its consider statement as a telecommunicate and wire run federation. In two hundred6, westerly joint give up its telegraph advantage and tensenesssed exclusively on currency transfers (Pearce & Robinson, 2011). Jorge Ochoa, Vice professorship of Finance and Raul Du any(prenominal), Director of somatic Communication joined The western heart Company (WU) in November 2008. The primary coil customers for silver transfers were immigrants that were pursuit give way opportunities in richer countries forward from their kinsfolk.When immigrants leave their home countries, they a great deal leave behind family members who opine on them for pecuniary support. This is most(prenominal) true in the role of poorer countries. Government regulators scrutinized the trading operations and fee-charging practices of currency transfer takings linees. westward centre is a leader in spheric currency transfer, p roviding pot with fast, reli able and admissionible ways to send bullion slightly the world. The westbound confederacy scrape is spherically recognized.Their run argon available by a network of over 375,000 executeer locations in more than 200 countries and territories ( westerly, 2009). Their consumer-to-consumer change transfer service enables people to send specie around the world in minutes. Their consumer-to- billet enterprise service go outs consumers with flexible and convenient options for making one- measure or happen bill defrayments. occidental confederacy believes that the grime strength, size, and reach of their globose network, along with the gubbins and dependableness to their consumers engage been essential in the ingathering of the business.As they continue to converge the of necessity of their consumers for fast, reliable, and convenient property transfer run, they ar likewise operative to enhance their services and provide their c onsumers with access to an expanding portfolio of payment and opposite fiscal services. The national law known as the Community Reinvestment Act (CRA) obligates federally insured buzzwords and depository institutions to function advert the exacts of communities in which they ope stride (Pearce, & Robinson, 2011). In March 2007, Federal substitute chairman Ben Bernanke stated, â€Å"the CRA reaf starchyed the long-standing principle that monetary institutions must divine service the convenience and needs of the communities in which they argon charted” (Pearce & Robinson, 2011). western sandwich unification serves many of the financial needs of immigrant populations, as a bank might, with a major bearing in poor and racially various(a) neighborhoods. western sandwich coupling is now being held up to the same standards as banks beca rehearse they ar both financial institutions. westerly meat’s customers ar mostly urban and poor.The exemplary len d oneselfr of its remittance service is a rugged-wage immigrant worker who lives in Urban America, pulls $15,600 annually and sends home $293 a month, almost 30% of his or her net periodical income (Pearce & Robinson, 2011). Heavy charges in the money transfer fabrication places economic burden on low-income immigrant families in the United States and in their communities of origin while creating and change magnitude re localiseation risk for Western marriage (Pearce & Robinson, 2011). Western northward has been facing numerous lawsuits, chief(prenominal)ly because of their lack of hearty responsibility.This has affected the partnership’s image and could authorizationly subjoin the risk that Western sodality faces in the competitive market. bodily Social Responsibility integrated social responsibility is chiefly perceive as a positive business political theory in the 21st century, notwithstanding some challenges. A authoritative expansion of basal business ethics, CSR establishes guidelines for ethical and socially liable behavior. It addresses how companies that want to satisfy regime and societal requirements should treat lynchpin stakeholder groups, including customers, suppliers, employees and the community (Mal Warwick Associates, 2008).Pros: One of the elements of CSR is that it causes companies such as Western colligation to reason beyond basic ethics to contract the benefits of combat-ready involvement in communities. In the article â€Å"The 7 Principles of business organization Integrity,” business strategist Robert flash argues that 21st-century companies must prove themselves to customers to physical body long-term relationships (Moment, 2004). Western trades union involves itself in the community by giving cover. Insinuates Western heart and soul to the local markets in which they operate.Cons: The main reason any company would object to participating in CSR is the associated cost. With CSR, c ompanies put one over to pay for environmental programs, more employee training and competent waste management programs. Proponents of CSR check out that any expenses to businesses be ultimately covered by gruellinger relationships with learn customers. However, David Vogel indicates in his Forbes article â€Å"CSR Doesnt afford” that investment in CSR programs may not necessary head in measurable financial results (Vogel, 2008).* corporal Citizenship. Western colligation’s international integrated citizenship is their commitment to enrich the lives of international citizens by expanding economic opportunity. by initiatives like the Western uniting Our World, Our Family program, they ar able to put their values into action (Western core, 2011). Western magnetic north corporate citizenship efforts waying on three primary areas: 1. Supporting Cultural cellular inclusion: Western marrow recognizes the brilliance of abeting individuals and famil ies build strong communities, in which all members privy contri notwithstandinge their distinctive talents and scent at home. . Creating Pathways to Opportunity: Western Union help diverse individuals and communities around the world profit their tremendous potential with scholarships reinforcement financial literacy, entrepreneurship, job training, and different skills necessary on the voyage to a better life. 3. advance Hope in the growing World: Western Union support economic learning and opportunities with infrastructure disclosement, community centers and access to applied science (Western Union, 2011).Western Union’s Current scheme. Currently, Western Union is using the free silver flow that is generated to salvation carnation and acquire rival money transfer firms in sound out to expand. Along with the repurchasing of roues and acquisitions, WU has donated millions of dollars to charitable organizations and some other countries. Their underway strat egy is coaxial diversification because they are getting firms that are related to them in terms of products and markets. They become engage growth of their grass by means of international expansion and the growth in the worldwide immigration population was alike capricious growth in the money transfer business.Although there is a higher risk associated with diversification, correspond to Pearce & Robinson (2011), the distinctive competencies of the diversifying firm are likely to urge on a smooth expansion. globalisation There are virtually s unconstipated factors that make global strategic planning complex. These factors are economic factors, political factors, geographical factors, labor factors, tax factors, superior get-go factors, and business factors (Pearce and Robinson, 2011). When you assure at the economic factors of a arena, you need to look at the GNP for the res publica, and the foreign telephone exchange rate.You as well need to consider the s ize of the market and the markets potential rate of growth. As out-of-the-way(prenominal) as the political factors are implicated, you bring forth to determine whether the country is stable, as well as, the showcase of political structure in the country. It is excessively all-important(a) to commiserate how foreign business is perceived in the country by the government, consumers and competitors. The geographic factors that you should be concerned with is the avail tycoon of raw materials, utilities, and the propinquity to export markets.Other globalization challenges you need to be aware of are the labor factors †whether you willing wee-wee the necessary skills available in the people in the country, tax factors †whether there are any tax breaks for foreign investors or if there is a grand tax rate for the country, groovy source factors †banking systems available in the country, and business factors †current manufacture information for competitors an d competitive situation. variegation There are excessively challenges immanent to diversification.Companies lots mold to diversify so that they erect acquire a rude(a) company that will potentially balance the strengths and weaknesses of the two businesses (Pearce and Robinson, 2011). Companies use diversification as a grand strategy in parliamentary law to increase assembly line value, increase growth rate, better use of investment funds, remedy stability of the company, acquire ask resources quickly, and tax savings, and increase capability and profitability.Trends in the Financial serve Industry. Current veers in the financial services effort is the use of a focus strategy. emphasis strategy, involves concentrating on a event customer, product line, geographical area, channelise of distribution, stage in the production process, or market niche. The underlie premise of the focus strategy is that the firm is better able to serve its limited instalment than compe titors serving a broader surf of customers. Firms using a focus strategy simply accommodate a cost-leader or eminence strategy to a element of the larger market.Firms may be able to differentiate themselves establish on meeting customer needs through specialty or through low costs and competitive set for specialty goods. This strategy is often take away for small, aggressive businesses that do not have the ability or resources to engage in a nation-wide marketing effort. such(prenominal) a strategy may also be appropriate if the buttocks market is too small to support a large-scale operation. Many firms start small and expand into a national organization. The trend in the financial services industry is that consumers are working outdoor(a) of their home countries.Many of these consumers have families back in their home country that they periodically send money to in grade to help them pay their bills. Western Union has a niche with this trend because they provide a nitty -gritty of easily getting the money to their family without having to have a checking account or if they have credit problems and owes the money elsewhere. Western Union guarantees that the money will be secure and delivered to the correct person. intrinsic Environment Financial teaching In 2008, Western Union’s market divide grew and delivered record levels of revenue and cash flow.Revenue was $5. 3 billion; $1. 25 billion was generated in cash flow from operations and WU handled $67 billion in cross-border consumer-to-consumer remittances. They also delivered an operating income margin of 26% for the year. Western Union and its consumers are feeling the impact of the global economic recession. They have trust in their strategy. Their plan is to focus on what they endure run and influence. They have a denounce that is recognized around the world. Their business generates significant cash flow.They have created a business place that consistently delivers strong margin s. They have built a distribution channel that is second to no(prenominal) and their global squad is focussed on a misfortunate list of priorities to poke growth. They provide vital services to consumers in more than 200 countries and territories. These services not only make a tremendous going in the individual lives of their customers, but the volume of remittances sent through Western Union helps demand many national economies, sidewalk the way for long-term growth.They also have the advantage of a globally recognized brand and unmatched worldwide distribution. Western Union plans to continue investment funds in their brand even in these tough times. Their brand represents speed, trust and reliability to their consumers worldwide. WU has launched a comprehensive new global brand initiative that embodies an compulsive and forward-looking fantasy for the company. Their vision is of optimism for their customers, company, agents and, employees. This vision shows their commitm ent to help people who are on the exit, pursuing their dreams.At a time when there is so overmuch pessimism in the world, it is believed that this Western Union message will serve as a source of positive energy in the marketplace, which should ultimately translate into hear appropriate and market share for the company. They will increase their technology spend to further develop tools that allow them to perform deeper synopsis on their customers. Western Union is sharpening their focus and directing investments to meet market share opportunities. They have demonstrated that their global team working together has helped them evolve market share in 2008.These employees were using Western Union’s four let out strategiesâ€strategies that will continue to drive their business forward: * despatch profitable growth in the global cash money transfer business * stretch out and globalize the consumer-to-business payments business * disturb in new products and services for target customers * Improve profitability by leveraging scale, reducing costs and effectively using smashing During 2009, Western Union will increase investment in technology and systems.They want to update their systems in order to move traditional and new services from virtually anywhere in the world, with exceptional speed. Western Union has a proven business model with significant financial strength. Alternatives and Recommendations Strategic Alternatives In order to publicize their commitments to social responsibility, Western Union should consistently re-evaluate their operations and look for areas of improvement. They can also look at what other companies in the industry are doing to be socially answerable and implement such procedures to their company.Because of the challenges inherent in globalization and diversification, it is important for Western Union to perform due diligence when introduction foreign markets. One of the challenges when globalizing may be the exchang e rate in different countries. Western Union may have to charge different fees depending on where they are and who their competition is. Recommended Strategy We believe that the company should stick with what they know and continue to repurchase shares and acquisitions. Repurchasing shares can generate a higher EPS and help use up excess cash.It can also increase the roe and raise demand for the stock on the open market. Their current strategy seems to be working for them and as long as they continue to re-evaluate their operations and stay put socially responsible, their strategy will be a success. The dirty dog line is that Western Union wants to pursue mergers in order to make money for the company and for shareholders.ReferencePearce, J. A, & Robinson, B. R. (2011). Strategic Management- Formulation, Implementation, and Control. (12ed) raw York, NY: McGraw-Hill/Irwin. Mal Warwick Associates, Initials. (2008). The Five Dimensions of CSR. Retrieved from http://www. malwarw ick. com/ Moment, R. (2004). The 7 Principles of profession Integrity . Retrieved from http://www. webpronews. com/the-principles-of-business-integrity-2004-07 Vogel, D. (2008). CSR Doesnt Pay. Retrieved from http://www. forbes. com/2008/10/16/csr-doesnt-pay-lead-corprespons08-cx_dv_1016vogel. html Western Union. (2011). Corporate Citizenship. Retrieved from http://corporate. westernunion. com/corporate_responsibility. html\r\n'

'The Strategy for Food Waste in Hk\r'

'Catalogue 1 Introduction ………………………………………………………………………………………………………………………… 1 1. 1 The definition of nutriment for thought flagellate ……………………………………………………………………………………………… 1 1. 2 The a lifts/generators of sustenance snitch…………………………………………………………………………………. 3 1. 2. 1 The witnessers of squ atomic do 18(a) cave in h arry in Hong Kong ………………………………………………………………………… 1. 2. 2 The seminal fluids of nutrient nullify in abroad countries/regions…………………………………………………….. 6 1. 3 The function in Hong Kong and solely overseas countries………………………………………………………………….. 7 1. 3. 1 The shoes in Hong Kong………………………………………………………………………………………….. 7 1. 3. 2 nourishment snitch situation in oversea countries and regions …………………………………………………….. 0 2 determination ……………………………………………………………………………………………………………………………… 13 2. 1 geek study of HK ………………………………………………………………………………………………………….. 13 2. 1. 1 minimization approaches for regimen for thought for thought coursen in Hong Kong ……………………â₠¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦. 14 2. 1. 2 utilise/ cycle approached of victuals wipe protrude in Hong Kong …………………………………………………. 7 2. 1. 3 moorage of minimisation and cycle of fodder knock off in schools……………………………………………… 24 2. 1. 4 finale of st straddlegies in HK …………………………………………………………………………………….. 27 2. 2 Minimization and st prescribegies in oversea countries …………………………………………………………… …….. 27 2. 2. 1 youthful Zealand…………………………………………………………………………………………………………… 27 2. 2. Korea ……………………………………………………………………………………………………………………. 28 2. 2. 3 chinaw atomic number 18 …………………………………………………………………………………………………………………. . 32 2. 2. 4 nerve of The vitamin E verbalize municipal public- re bias corporation territorial dominion………………………………………………………………… 34 3 Critical comparability……………………………………………………………………………………………………………… 7 3. 1 Comparisons ………………………………………………………………………………………………………………… 37 3. 1. 1 Recycle/ apply qualification ………… ………………………………………………………………………………… 37 3. 1. 2 distinct campaigns and police forces in approaches to forage downs in una a same(p) countries ………………… 39 3. 1. 3 Technologies utilise in sustenance negate……………………………………………………………………………… 41 3. 1. Barriers in f ar shove off employ/ re determination in Hong Kong………………………………………………………….. 45 3. 2 Recomm closeations …………………………………à ¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦Ã¢â‚¬Â¦. 47 4 Conclusion…………………………………………………………………………………………………………………………. 50 References …………………………………………………………………………………………………………………………… 1 1 Introduction 1. 1 The definition of intellectual nourishment for thought molder fit to the forge of nutrient for thought and Agriculture Organization of the join Nations (FAO, 2012), global provender payoff hold back out attach 70% by 2050 on the usance of meeting the demands of the ripening adult male population under menstruum harvest- measureion and inlet. However, thither argon to a greater extent(prenominal)(prenominal) than than wiz terce of the fodder fictive to mean solar day beingness superabundanced or lose. f atomic number 18 dissipationd or intellectual nourishment passage whitethorn subject a range of issues not l champion around(prenominal) on the surroundings however withal on society and economy.Therefore, both veritable countries and stopment countries dedicate to vitiate and slew forage pine. In ordinary, viands barbaric or nutrient loss refers to the f ar that is discarded or lost uneaten. It occurs on all step in the forage range of mountains ( mental image 1). In veritable countries, closely victuals disroot occurs a t the usance stage, duration in ontogeny or low-in count countries, intellectual nourishment for thought for thought is boastd during proceeds. Diffe hold countries or regions stick their own definitions of aliment redundance, relating to provender furious sources, the situation of countries, their population and so on. 1 form. 1. The steps where regimen wild occurs (Heta-Kaisa Koivupuro, 2011) ? coupled Nations nourishment exorbitance is victuals loss which occurs at the sell and final inlet stages because of the behavior of throwing a federal agency of diet by the retailers and consumers ( Gustavsson, J. , 2010). The loss entangles biomass which is in the stolon place meant for human aspiration spartanly withaltually employ for whatever early(a) purpose, much(prenominal) as arouse or puppet scarper. Mean enchantment, f be wild in United Nations scarcely consists of decline in viands regimen mass during the doing, raiseharvest and to uch on stages tolerant of of the in tender spark off. Hong Kong The definition of solid viands for thought pine a substance in Hong Kong fluent privy not be unified, notwithstanding f ar molder dejection be split into cardinal kinds at least. They ar uncooked forage and pointless cooked nutrition. The first kind of diet shove along whitethorn be easily dealt with comp atomic number 18d with the atomic number 42 kind, because it normally embroils the s cigargontty fond regimen such as re parade peel, kernel and eggshell, while the excess cooked sustenance whitethorn intermingle up with oil, tissue and besidesthpick which take up the handling methods for f are intemperance. ? Australia 2In Australia, intellectual nourishment for thought reign off means an thrown-a elan(prenominal) stabbing or cooked nutriment discarded during or aft(prenominal) nutrition forwardness that is no longer fit for consumption or desirable (Nathalie Jean-Bapti ste, dickens hundred9). It includes spoilt cooked menstruate, excess cooked forage, vegs and fruits peelings, beverage, undesirable crude(a) intellectual nourishment and meat throw away. ? atomic number 63an Union In European Union, viands neutralise is be as any nutrition substance, raw or cooked, which is discarded, or intended or require to be discarded. ? United States In United States, the intellectual nourishment muck up is defined by the United States environmental Prottection Agency.The definition is uneaten pabulum and regimen preparation eats from residences and mercenary establishments such as bleed market stores, peacefulnessaurants, and upgrade stands, institutional cafeterias and kitchens, and indus visitation sources give care employee tiffinrooms ( United States environmental tax shelter Agency, 2006). Although the definitions of viands fumble vary in polar countries and regions, the adverse impacts that fare burn out ca utilise a re so flagitious that more financial aid should be nonrecreational and mo re fills should be taken to reverse and treat it. . 2 The sources/generators of nutriment liquidate Developed and developing countries actually devastate roughly the same tally of forage (670 and 630 trillion tonnes, respectively). The difference is at what impart in the nourishment hand over chain the muff occurs. In eminently-developed countries, the spunkyest raft of permissive drive out is at the retail and consumer level; in developing countries it occurs roughlyly at the post-harvest and processing level due to limitations in transit, store and processing.Therefore, HK, as wholeness of the approximately developed commonwealths in the orbit, its nutrient raging in the main comes from the retail and final consumption stages. 3 In station to p operatee or throw outcel nourishment eat up usefully, the ruff way is to learn close to the sources or generators of diet sn itch. Because if we try out scoop to avoid solid intellectual nourishment louse up or aliment loss from its sources, the anformer(a)(prenominal) processes for decrease counterbalance or loss during the pass offing stages peck be avoided, so that we empennage fulfil currency and resources. The sources of intellectual nourishment macerate of contrary countries and regions are illustrated under. . 2. 1 The sources of feed emaciate in Hong Kong The sources of sustenance wase in Hong Kong commode be divided into both parts, major source and separate sources. hedge 1 shows the contrary sources and their components and characteristics. The major source is internal or residential. According to the statistic of Friends of The nation, municipal aliment lay expend tofulness accounts for 70% of all victuals pay off stimulated in Hong Kong, with an measuring of 2,300 tonnes per day (Friends of The globe, 2009). The motives for substructure(prenominal) nu trition thieve are various.For fount, diet is meretricious or close to citizenry may curtail the intellection that when inviting others to dinner, they collect to parade more than rich so that they would not lose face. Table 1. 1 descents of solid nutriment licentiousness harvesting in HK Amount of thriftlessness Source Major Components Characteristic (hemorrhoid/day) bobble cooked fodder Supermarkets and drinking stores Undes irable raw sustenance Spoiled cooked intellectual nourishment tautological cooked nourishment Including evitable and Residential/Domestic Vegetables & fruits peelings requi come in Beverage Undes irable raw regimen 4 Most are Avoidable 90 2,300 spunk put away Excess cooked fare Vegetables & fruits peelings Restaurants and Beverage hotels Undes irable raw sustenance warmheartedness scraps Vegetables & fruits peelings Beverage intellectual nourishment pains Undes irable raw victuals Meat scraps Excess cooked victu als Beverage Schools Vegetables & fruits peelings Meat scraps Avoidable are edible or edible before spoilage/damage) indispensable are inedible victuals material like veggie peels, bones, etc. un evitable Including avertable and 41 unavoidable Including avoidable and 900 unavoidable Including avoidable and 964 The major source is domestic or residential.According to the statistic of Friends of The Earth, domestic forage wild accounts for 70% of all sustenance macerate captured in Hong Kong, with an get of 2,300 tonnes per day (Friends of The Earth, 2009). The reason outs for domestic nutrition tempestuous are various. For standard, viands is cheap or slightly right-hand(a) deal may hold the idea that when inviting others to dinner, they confuse to dedicate more than luxuriant so that they would not lose face. The other sources are supermarkets and stores, nutrient industry and schools. The nutrition industry consists of nourishment chains, Chinese restau rants, hotels, bakeries, supermarkets, markets, intellectual nourishment kindlers and so on.The industry produces 900 tonnes of pabulum eat per day (Friends of The Earth, 2009). And schools impart 15,000 tonnes of aliment gaga per course of study. Meanwhile, nutrition nullify in Hong Kong hobo be mark off-apart into two kinds at source, they are 5 non- serviceable kind which includes glasses, tinfoil, cling film, carton boxes, tensile bottles, aluminum only whent ends and tin stomachs, and recyclable kind, including meat, bones, bread, rice and noodles, vegetable, fruit and egg shells ( physical bodyure 2). soma. 1. 2 Separation of viands for thought for thought exorbitance at source (EPD, 2011) 1. 2. 2 The sources of fodder blow in oversea countries/regionsIn Australia, the victuals burn out mainly comes from nursing home or residential with an gist of rough 3 cardinal tonnes per socio-economic class. Approximately 20% of forage go forth b e thro wn away subsequently its bargain for in Australia In European Union, diet ravage are from family units, supermarkets, restaurants and the aliment supply chain. Over 50% of edible and healthy viands in EU is scratch offd individually class and the follow is 89 one gazillion zillion million tonnes per course of study. 6 digit. 1. 3 Sources of pabulum take in fir cereals, by region (Agree, 2011) unalike the developed countries, food extravagance in developing countries is motherd at lower levels.numberure 3 uphold identified the source level of food moulder. From it, we mess fit that in the developed countries like Europe and labor union America, nigh 60% of the food fuck up in cereal jot products occurs at consumption stage. Conversely, in the developing regions, like southernmost Asia and sub-Saharan Africa, more than 60% of food ball up 1. 3 The situation in Hong Kong and oversea countries 1. 3. 1 The situation in Hong Kong According to the statistic o f EPD, in Hong Kong, well-nigh 3,584 tonnes food be adrift are produced e preciseday, accounting for a third of all self-colored looseness in Hong Kong.One third of them originates from 7 commercial messageised and industry (C&I) sector, and the stay comes from households. So households produce big touchstone of food go off in Hong Kong. The meretriciousness of food mess up from C&I sectors has increases more than double in the last decade, from 400 tonnes in 2002 to 1,056 tonnes in 2011 (numberure 4). Also, we back let on from flesh. 2 that supermarket jail 29 tonnes edible food all(prenominal)day. piss. 1. 4 Basic food abscond situation in HK (EPD, 2012) bodure 5 futher illust rank a conferty issue in Hong Kong.About 3,200 tonnes of food are direct to landfill e rightfully day, which equals to the capa city of 126 double buses, and the equal for deal with food wipe out is more than 2 million per day. What‘s more, if the rate continues to i ncrease, the landfills in Hong Kong could bring in mental object in 2013. Therefore, the situation of food raving mad in Hong Kong is not comfortable and the rouses of Hong Kong‘s landfill are too heavy. Every whateverone in Hong Kong should realize this disassemble situation and try best to minimize food dispel in daily life. 8 Fig. 1. The situation of food elope in Hong Kong (Hong Kong Stories, 2011) General crusade of food xerox in Hong Kong is illustrated in throw 6. In realise 6, Line 1 repre directed commercial and industrial food fling off, Line 2 represended domestic food louse up and Line 3 represented municipal solid brag. From the figure below, we advise break up that in Hong Kong, the sight of domestic food countervail has been minify in the past 10 years, while the commercial and industrial food risky has unploughed going up importantly and accounted for 30% of municipal solid unwarranted in 2009, which is 20% more than that in 1999.The r ising rate is really a serious problem and more attention should be paying(a) in aver to condense food take in material and the taste of landfill. 1 2 3 Fig. 1. 6 Volume of municipal solid drive off in Hong Kong (FoE, 2010) 9 The reasons why the come up of food raving madfulness is slightly prodigious and why it becomes a severe issue are listed below: ? many a(prenominal) diners energize more food on the nursing home than they apprise eat. According to parkers attain‘s thought: only 13 part of responders pile finish allthing in their plates and close 87 pct of them always odd approximately food behind, 44 per centum of these respondents say that they much cadences left over 30 part or more.Especially, at buffets and all- you- buns-eat sushi or hot pot restaurants, patrons crumb be tempted to pile too oftentimes on their plates. ? Disposing is cheaper than use or re- using. For example, the unsold vegetable and fruit ordain be dumped cursory even around of them are still impertinent in the undermentioned day, because the wear upon toll of picking is blueer(prenominal) than the benefit of selling. 1. 3. 2 feed untamed situation in oversea countries and regions ? Global Fig. 1. 7 Global food godforsaken (PWC, 2012) 10In Global, fairish like the per centum of food bollix in Hong Kong, one third of the food is flubd or discarded. nutrition drive out in industrialised countries is as spirited as in developing countries, merely in developing countries more than 40% of the food losings occur at post harvest and processing levels, while in industrialized countries, more than 40% of the food losses occur at retail and consumer levels.. normal 8 shows that the per capita food loss in Europe and North-America is 280-300 kg/year.In sub-Saharan Africa and sulphur/ southeastward Asia it is 120- clxx kg/year. The union per capita production of edible parts of food for human consumption is, in Europe and North-Ame rica, astir(predicate) 900 kg/year and, in sub-Saharan Africa and South/Southeast Asia, 460 kg/year (Jenny Gustavsson, 2011). Fig. 1. 8 fodder lavishness in divergent regions (Jenny Gustavsson, 2011) ? Korea Korea has a very short history (less than 10 years) for food go off cycle by its own way. In Korea, the division of food unfounded which is separately cacheed is over 80%.Although the bemuse-and-take techniques are forward-looking and over 80% of collected food blow is carrying to feedstuff and modify, the demand of the products is low in the whole society and the product situation is difficult. Nowadays , Korea has reconsidered its recycle carcass to construct a new and sustainable structure. ? mainland China 11 The food bumble recycle technology in mainland China is excessively comparatively mature with an eight-year history. Now chinaware recycles an amount of food bluster equivalent to the tidy sum of drift processed daily in two 900-tonne incineration kit and boodles.The food forsake which accounts for 75% of total food unfounded collected is born-again into copper feed and 24% food run off is converted. The rest 1% is inured for other uses. ? U. S. In the U. S. , more than 34 million tonnes of food chase away was generated in 2010 (U. S. environmental resistance Agency, 2012). viands attracts up the largest partage of idle going into municipal landfills and combusted for dynamism recovery in the U. S. (Fig. 9). Fig. 1. 9 forage intemperance in the U. S. (U. S. Environmental Protection Agency, 2012) ? AustraliaIn Australia, the amount of food looseness discarded per year is most 3 million tonnes and 95% of compostable items are food barbarian (Australia Institute, 2005). The food languish production increased by 0. 5kg/w in 2007 compared to that in 2004 (3. 7kg/w). Sydney, the city with the larest population in 12 Australia, gene pass judgment a high field of food hazardous in their world(a) bins with clo se to 50%. Another study is engraft to analyze the cost of food burn out in Australia. Australia dispels more than $5. 2 billion in food a year (Penny Pryor, 2011).This is quite a kettle of weight of money and it suggests that the situation of food risky in Australia is to a fault serious. The study reasons that t he biggest and most self-make motivator to trim down food angry in Australia is economy money. Fig. 1. 10 Cost of food chase away in Australia (Penny Pryor, 2011) ? Europe Excluding untaught food ball up and fish discards, somewhat 90 million tonnes of food is neutralized yearly or 180 kg per capita per year in Europe. It has been communicate that if no action is taken, the amount of food unwarranted in Europe testament r all(prenominal) 126 milling tonnes by 2020. 2 Finding 2. 1 causa study of HK 13 2. 1. Minimization approaches for food emaciate in Hong Kong There are legion(predicate) an(prenominal) another(prenominal) approaches are proposed fo r the minimization of provender waste in Hong Kong. exclusively most of them are proposed by volunteer establishment. And a general guideline for decline and care of food waste for food service institutions are proposed by parking areanesser Action: Fig 2. 1 The guideline for food waste decrease and management from chiliadser Action And other approaches or brass sections for lessening of food waste include: nutriment Bank victuals Hong Kong is the only food slang in Hong Kong dedicated to redistributing trim food to throng in need.By providing a bridge among the food industry and the sharp-set of Hong Kong, they provide a solution that simultaneously cuts food waste and feeds those most in need. Fig 2. 2 The mission of victuals Hong Kong from the website of pass Hong Kong 14 food for thought nonesuch Besides, sustenance Angel is a food bear and assistant syllabus which dish up to knock down the generation of food waste in Hong Kong. They merge food produ cers and charitable plaques in topical anaesthetic anaesthetic communities to ensure transactionual food provision to the underprivileged. nutriment cycle Sche me sustenance cycle constitution is a cow come acrosser food assembling program operated by CTU Education earthing Ltd.The scheme is aim to collect and process unsold sweet-scented food from market and make delicious vegetarian lunch which offers to sluggish trainees in readying center field at lower price. It can save over 30,000 kg of wasted food yearly. nutrientlink world Limited is a registered non-profit organization which is aim to fight hunger and poverty by minimizing food wastage. The organization collects surplus and donated food from various hotels and F&B outlets and delivers it to shelters and to the needy, thereby generating a sustainable food- cycle strategy. The fodderlink carrying out is as follows: Fig 2. 3 The intellectual nourishmentlink operation from foragelinkThe unbidd en organizations in addition launched several activities to enkindle public awareness of reduction of food waste, like the ? exempt Food Day on Wednesday? proposed by putting surfaceers Action and ? exhibition slight yearn Less? proposed by Friends of the Earth. 15 Fig 2. 4 The notification of but Food Day on Wednesday from Save Greeners Action Fig 2. 5 The photo from the website of Friends of the Earth carrying into action: These actions are accommodating to cut off the generation of food waste, but there is no real figure of the reduction amount of food waste by these actions, and without the assistant of organisation, the outlet is limited. 16 2. . 2 Reuse/recycle approached of food waste in Hong Kong Kowloon mouth retain converting Plant To gather go through with(predicate) and information on aggregation of source conf employ food waste and the practise of biologic technology to recycle food waste in Hong Kong, the Environmental Protection incision dev eloped the Pilot converting Plant (KBPCP) at the Kowloon utter suck cycle Centre (KBWRC) in mid-2008. writ of execution: The total discourse capacity of the KBPCP is 500 tonnes of food waste feedstock per year and more or less nose candy tonnes of compost product will be produced. Fig 2. 6 Treatment Process of KBPCP from website of EPDFood cop recycle confederation Scheme EPD launched the ? ‘Food redundance cycle Partnership Scheme‘‘ unitedly with commercial & industrial (C&I) sectors in 2009 to promote good food waste management place and to gain experience on food waste source separation and cycle. Implementation: During the operation of the ? Food muck up recycle Partnership Scheme‘, 17 participants practised food waste source separation and dictated the separated food waste in the designated array bins provided by EPD at the assigned accumulation points for collectio n by EPD to the KBPCP for cycle.EPD was trustworthy for k illing the charm bins. At present, the participants of the scheme already increase to 70. Fig 2. 7 handbill of Food counteract Recycling Partnership Scheme from website of EPD essential tout Treatment Facilities The Environmental Protection Department (EPD) has discrete to develop the fundamental superabundance Treatment Facilities (OWTF) which will be developed in two grade. The OWTF will postulate biological technologies †composting and anaerobiotic digestion to stabilize the ingrained waste and turn it into compost and bio accelerator for recovery.The bio accelerator produced in all(prenominal) phase of the OWTF could be utilise as renewable energy. A site search to locate commensurate sites for the OWTF was completed. The proposed sites for the first phase and back phase of the OWTF are turn up at Siu Ho grim of North Lantau and Shaling at North soil respectively. 18 Fig 2. 8 Artists Impression of the perfect brag Treatment Facilities from website of EPD Implementation: The total daily discourse capacity of OWTF is 400-500 tonnes of original waste per day, and some 28 million kWh of surplus electricity can be supplied to the index finger storage-battery grid per year.The first phase of the OWTF may be accomplished in 2 or 3 years, it can treat 200 tonnes of fundamental waste (mostly food waste) per day. 19 Fig 2. 9 The process of anaerobiotic digestion from website of EPD electric converter Some of the bes in commercial & industrial sectors are forthwith slip awayd in situ by galvanising composter proposed by EPD. Food waste is putted into a mechanical digester †through fermentation and other processes to turn most of it into wet and carbon dioxide within one day. And the eternal rest will be sent to landfill.Implementation: The composter can descend the intensity of food waste sent to landfill in some extent, but there is not authoritative data for the reduction slew as the composter can be purchased from private producer. 20 Fig 2. 10 The electrical composterâ€Gomixer from Hong Kong chocking on food waste Food bollix up Recycling Projects in lodging Estates Environment and preservation Fund (ECF) has allocated $50 million as support and has launched a sustenance intercommunicate, ? Food uncivilised Recycling Projects in lodgment Estates? , to get ahead the separated ingathering and cycle of food waste from households in July 2011.Implementation: 11 nations were prone funding support in the first phase with a total allocation of rough $9 million. The participating acress have received subsidies to undertake on-the-spot(prenominal) treatment of source separated food waste and to march on households to reduce food waste. And it is estimated that close 45 additional estates could be covered in the cooperate phase. Besides, EPD has overly commissioned the Hong Kong productivity Council (HKPC) to operate a help-desk service for the potential drop housing estate applicants and those participating food waste separation, compendium and recycle political sympathies departments.The services include: ? assisting in identification of a fitting site for installing the food waste treatment installation within the housing estate prior to formal application; ? providing headmaster and technical advices to potential applicants or participating disposal departments during planning and, implementation stages; and ? conducting valuation of performance, effectualness and outcomes. 21 Fig 2. 11 The poster of Food botch Recycling Projects in Housing Estates from website of help-desk service for food waste recycling project in housing estateFood waste recycling technology-Bokashi Greeners Action introduced the food waste recycling technology-Bokashi from forward-looking Zealand in 2010, this technology can help pack dispose their food waste at home. Implementation: More than 170 households has bought this food waste recycling t dok, and some pilo t projects have been launched in schools and residential area in these two years. 22 Fig 2. 12 The poster of Bokashi from website of Greeners Action Individual recycling confederation Green supposition is a recycling fellowship in Yeun Long which collects utilise school lunch boxes and separates and recycles both the food waste and plastic container.Generally, they can recycle about 800 thousands of school lunch boxes every day, which can reduce the food waste in some extent. Fig 2. 13 The head discoverer from we bsite of Green Idea Kowloon ergonomics Ltd is a recycling company using the food waste to produce feedstuff. It can recycle about 50 tons every day to produce different kind of feedstuff. Hong Kong native Waste Recycling reduce is a company which can offer a serial of recycling service for constitutive(a) waste. They use the advanced technology combing the experiences from local keen and oversea countries to provide a help in recycling of food waste in Hong Kong . 23 Fig 2. 4 The heading from website of HKOWRC 2. 1. 3 Case of minimization and recycling of food waste in schools 2. 1. 3. 1 The situation of food waste in schools Solid waste is divided into some 60 categories at present, of which the ? dining wares do of plastic/poly- foam? covers essentially all types of disposable food and drink containers and eating utensil. In 2007, the volume of such waste we wedded of amounted to about 199 tonnes per day. Disposable food containers are unremarkably do of non-degradable materials that will stay in earth forever and tarnish the environment, which increases the difficulty of recycling of food waste. . 1. 3. 2 The objective of Green luncheon scheme To reduce the generation of food waste and protect our environment, schools can help by drawing up and adopting a suitable unfledged lunch polity base on the principle of ? Reduc ing taint and Minimizing Wastage?. 2. 1. 3. 3 Analysis of repast grade in schools repast arrangements in s chools can be mainly divided into two types by the containers they utilise: useful or disposable containers. recyclable containers mean those are hardy and durable enough for ingeminate washing and use.Meals served in useful containers may be portioned both on-the-spot(prenominal) or off-site, namely, important/On-Site Portioning and Off-site Portioning. aboriginal/On-Site Portioning Cooked food is delivered by lunch suppliers to schools in bulk, and and thus re- conflagrateed and portioned in-situ for dissemination to students. 24 Fig 2. 15 Central/On-Site Portioning from Green Lunch road map off-site Portioning Cooked food is constituted and portioned at the kitchens of lunch suppliers and delivered to schools in lunch boxes consort to the amount ordered. Fig 2. 16 Off-Site Portioning from Green Lunch Guideline . 1. 3. 4 Proposal for central/ on-the-scene(prenominal) portioning in schools The central/ on-the-scene(prenominal) portioning is better than off-site po rtioning in many aspects. Therefore, schools are proposed to utilize central/ on-the-scene(prenominal) portioning in order to reduce contamination and minimize wastage. The benefits of central/on-site portioning in schools include: 25 ? All dining wares employ including trays, dishes, bowls, chopsticks, knives and forks, etc. are washable and reusable. Basically, no disposable containers and cutlery are employ, which increases the potential of recycling of food waste.The amount of food portioned can be flexibly adjusted on petition by students, which can reduce the potential of generation of left over by student. And the volume of lunch supplied can be adjusted according to the remnant generated, which reduce the food waste and wastage considerably. According to t for each oneers and students, eating at canteens is much more overjoyed and exciting than in classrooms, providing a unique social action mechanism for students. ? ? Fig 2. 17 word picture from Green Lunch Guidelin e 2. 1. 3. 5 Implementationâ€an example of school of central/on-site portioning St.Edward‘s Catholic indigenous School is a successful example applying central/on-site portioning. The school played out more or less a year for the arrangement of central/on-site portioning; the preparation works include the excerption of proper place for central/on-site portioning and the lunch supplier, and communication with the student‘s arouses. subsequently the application of central/on-site portioning, the volume of food waste has been reduced and most of them can be recycled. Besides, the food waste separation and assembly processes set up the environmental awareness of students, and the 26 isposable lunchbox is not used for lunch anymore. Fig 2. 18 The situation of central/on-site portioning in St. Edward’s Catholic native School from Green Lunch Guideline 2. 1. 4 Conclusion of strategies in HK The EPD has proposed several schemes for the recycle or recycling of food waste in late years, including strategies of collection and recycling facilities. Therefore, we may forecast that the change magnitude volume of food waste will be turn into useful product or renewable energy by stiff separation.But for the strategy of minimization of food waste, most of them are proposed by voluntary organization without the political help. 2. 2 Minimization and strategies in oversea countries 2. 2. 1 New Zealand The disposal supports and subsidizes households to employ/recycle the food waste on-site. Non-edible food waste is regularly composted both through a collection service, with home composting or with a worm farm. A mint of households in 2007showed that 79% shit in a way to go along food wastage, 63% carry out home composting and 10% have a worm farm. And one 27 f the ways to prevent food wastage for supermarkets and grocery stores is donating the food to the voluntary organizations, like Food not Bombs which uses their discarded food to feed large number at film nights and markets. Kai to convert is a food waste collection scheme for restaurants and businesses. The scheme collects food waste from restaurants and takes it to the Living Earth plant at the grey Landfill, where the material is mixed with green waste and used to produce compost. It was initially a trial scheme with governing funding but is now a user pays scheme involving 50 businesses.Up until the end of 2006, the Council had collected 456 tonnes of food waste. Fig 2. 19 Kai to compost collection truck 2. 2. 2 Korea Korea government has forbidden direct landfill of the food wastes in 2005 and has paid much causal agency to build up the collection system and utilize/recycling facilities for food waste: a. The reuse/recycling methods of food waste: illogical collection method of food wastes at source: 28 b. Dry Feedstuff Production: c. unwavering Feedstuff Production: 29 d. compost: e. Anaerobic Digestion Facility: 30 Besides, Separated disposal of fo od waste is now legally mandatory.The waste collectors can avert to collect the food tripe or fine the tipper if the trash was not separated well. Through this comprehensive food wastes reduction plan and fiscal support for installing food wastes recycling facility, the recycling rate of food waste is already up to 94% in 2005, from 45. 1% in 2002. And in Seoul, the collecting rate of food waste is up to century% in 2008. For the reduction of food waste, Seoul is about to pop a trial run of large automatic receptacles that weigh the amount of food protest deposited into them by each household and charges accordingly.Fig 2. 20 â€Å"Pay-by-volume” white-hot Q system for food waste 31 And the dumping of waste pissing generated by the processing of left over(predicate) food into the sea will be ban from 2013, according to the Ministry of Land, Transport, and Maritime affairs. The Ministry of Environment buy the farmed to reduce on the bio shoot a line plant which can turn the waste water system into clean fuel in new years. 2. 2. 3 mainland China Since the fiscal year 2001, the EPA has been subsidizing the local town, county and city governments to establish their kitchen waste collection and recycling programs.In 2007, the kitchen waste recycling program has been integrated into EPAs â€Å"2007-2012 mankind training architectural plan-General Waste alternative Recycling progress Program”, in order to achieve proper treatment of all collected kitchen waste and to complement the ? slide fastener Waste? policy. The schemes for reuse or recycling of food waste include: [1] Education and Promotion of Kitchen Waste Recycling Program push â€Å"Green Eating Habits †Kitchen Waste Reduction Campaign”; drill kitchen waste recycling training seed instructors, and conduct on the job training for implementation organizations responsible mortalnel; ? ? ? trim with schools, communities and environmental groups to conduct educ ation, promotion, evidence and training activities; ? Prepare promotional brochures and handbooks to teach residents how to conduct kitchen waste sorting, collection and reuse; ? ? Promote kitchen waste recycling on the radio, rail line TV and news media; build up kitchen waste recycling webpages on central, county and city governments websites. [2] bring Kitchen Waste Collection and Transportation musical arrangement ? Implement kitchen waste collection and transportation from households, schools, military bases and punitory facilities; 32 ?Modifications or purchases of slobber trucks for use in kitchen waste recycling, and purchases of kitchen waste recycling buckets; ? ? devise collection zones, routes, transportation modes, and develop collection goals; Establish temp storage sites for collected kitchen waste, purchase transfer mac hinery and cleaning equipment; ? Organize demonstration of a better-performing local government program, mitigate collection system and man - fountain input. [3] Establish modes of kitchen waste reuse ? Reuse of kitchen waste as pig feed later high temperature sterilization, or use as organic fertiliser after composting; Inspect pig farms permitted to use recycled kitchen waste as feed to ensure proper feed sterilization and pig immunization; ? Establish regional kitchen waste reuse factories/sites, such as high temperature sterilization facilities, composting sites, anaerobic digesters etc. ; ? ? Transport kitchen waste to spread out and compost manufacturers to produce organic fertilizers; Enhance the fiber and technologies of the compost produced by local governments‘ composting plants; ? Provide incentive attention and subsidies to private sector to aid establishment of kitchen waste recycling and reuse facilities. 4] Develop markets for recycled kitchen waste products ? ? ? Establish long-term flavor and quantity data for recycled kitchen waste; Develop and guess pencil eraser inspection and tests for kitchen waste recycling and reuse products; Develop and evaluate other feasible kitchen waste reuse options, such as number into feedstuff or adopt anaerobic fermentation; ? Work with Council of Agriculture and other local governments agriculture competent governing or associations to jointly promote kitchen waste reuse means. 33 Fig 2. 21 Compost Plant in TaiwanBesides, in order to continue the kitchen waste recycling efforts and assist the local governments in establishing diversified kitchen waste reuse system, the following kitchen waste daily collection and reuse goals have been set among 2007 and 2012: Table 2. 1 kitchen waste daily collection and reuse goals Implementation: At present, all 319 local town and township governments nationwide are implementing the kitchen waste recycling program. Through the unite efforts of EPA and local governments, the recycling rate of food waste is up to 36% in 2008 and 1977 tonnes of kitchen waste in Taiwan is recycled every day in 200 9.Of the methods used to treat food waste, about 75% undergoes steam treatment to make pig feed, while 24% enters composting systems and 1% undergoes other processes, like incineration. 2. 2. 4 Case of The East alcove municipal Utility district 34 The East Bay Municipal Utility District (EBMUD) of the San Francisco Bay Area has done a great job in converting food waste to methane gas and later to energy. The East Bay Municipal Utility District‘s food waste energy project turns order of food waste to energy through all in all inwrought process. The eco friendly method helps pile convert their food waste to methane gas.EMBUD utilize the instinctive process like the Muckbuster to turn the raw food waste to clean energy. Muckbuster is an anaerobic digester from a green firm called the SeaB and turns deserted food items into clean energy. The container like system has the capability to recycle half(a) a ton of food waste to generate the amount of energy required to run 150 c omputers. Muckbuster is outfitted with advanced technologies to derive methane from food waste through a biological process. The methane is later flowed through a heat and magnate system to produce electricity. Fig 2. 22 Muckbuster Anaerobic Digester from EcofriendBesides, the East Bay Municipal Utility District (EBMUD) collects and carries the autumn pumpkin waste into its plants to produce energy. Every year in the U. S. , after the Halloween, heaps of pumpkins will move to the landfalls. This food waste is also recycled in EBMUD. The bacterium breakdown of the pumpkin waste along with other food waste will produce methane gases, which can be used to produce energy. 35 Fig 2. 23 Pumpkin great power from Ecofriend The EBMUD was honored in 2007 with a grant of $50,000 by the EPA to march on it develop new methods for digesting food waste to produce methane gas.The power produced by the EBMUD is used to run the regional waste water treatment plant. Fig 2. 24 EBMUD’s exampl e of turning waste into energy from Ecofriend 36 3 Critical Comparison 3. 1 Comparisons Mountains of food waste are a growing problem in many affluent countries. In Hong Kong, where people love to eat out, leftover food takes up much of the limited station in city landfills. So the sound judgment for Hong Kong recycle/reuse energy, technologies employ and strategies or policies conducted with overseas countries is very prodigious. 3. 1. Recycle/Reuse power In fact, the data of food wastes generation per person per year in different countries are different. In New Zealand, about 258,886 tonnes of food waste goes to landfill each year. That works out to be 64kg per person per year. And thats just in New Zealand. At the meanwhile, it‘s about 70kg per person per year of food waste in UK. And the US gets a number of approximately 82kg per person per year dumped into the landfill. In addition, there are several data about food waste by different country shown in ascertain 3. 1. go into 3. Food waste in different countries (kg/cap/year) In affection of the population in HK, we can calculate the food wastes per person per year. According to the Census and Statistics Department in HK, the population of HK is 7,136,300 by 37 Mid-2012. By the probe of EPD website, there is approximately 3,584 tonnes food waste produced in Hong Kong every day. And 3200 tonnes of food among it is sent to landfill each day. So 3584tonnes ? ascorbic acid0kg /tonnes 7136300 3584tonnes ? 1000kg /tonnes 7136300 3200tonnes ? 1000kg /tonnes 7136300 3200tonnes ? 1000kg /tonnes 7136300 ? 365 = 197kg person /year, = 0. 0kg person /day of food waste generation and ? 365 = 164kg person /year , = 0. 45kg person /day of food waste dumped into landfill would be the results. From the e property of the data above, we can conclude that HK is one of the largest generation areas of food waste in the world and that the most important and expeditious way is reducing the food waste generation kind of than recycling and reusing approaches which are also indispensable. We assume that the equipoises are all recycled or reused in a sustainable way. The recycle/reuse efficiency would be like that: 3584 ? 200 ? 100% = 11% 3584 That is to say the recycle/reuse efficiency of food waste in HK is 11% at most. Table 3. 1 Food waste recycling rates in developed Asiatic nations. artless Korea (2005) japan (2007) Taiwan (2008) Singapore (2008) annual Food Waste Generated (ton) occasional Food Waste Generated 4,755,220 20,000,000 1,899,379 568,000 13,028 54,795 5,190 1,556 38 (ton/d) Annual Food waste recycled (ton) Daily Food waste recycled (ton/d) Food waste recycling rate, % macrocosm (million) Daily Food Waste Generated per capita(kg/d/ca) Daily Food Waste Recycled per capita(kg/d/ca) 0. 6 0. 09 0. 08 0. 04 0. 27 0. 43 0. 23 0. 31 48 127 23 5 94 20 36 12 12,246 10,956 1,889 186 4,469,907 4,000,000 691374 68000 Whereas, Table 3. 1 in the main illustrates the food waste rec ycling rates in developed Asian nations. With the observation of this figure and the assumed recycle/reuse efficiency in Hong Kong, we can get the idea that the gang of strategies employ and the technologies applied processes better in a country order: HK, Singapore, Japan, Taiwan, and Korea. 3. 1. Different campaigns and laws in approaches to food wastes in different countries 39 3. 1. 2. 1 Korea 1994: Start composting demonstration projects in 12 cities. 1995: Korean government established the ? committee for the Management of Food Waste‘ 1996: Kyonggi Province declares ? War against food waste? 1999: Food waste collection in Suwon metropolis (Kyonggi Province) 2002: Establish a voluntary agreement for food waste reduction ( in confederation with FIFA world cup) 2005: Direct land- fill up of food waste has been banned 2006: 2,520 tons of bloodline and food waste per day was dumped into the ocean 3. 1. 2. 2 Japan 2001: Food waste recycling law 2004: Regional food waste composting in Sendai 2006: Recycling of Organic Waste in Aya town †reached 20%, food-related business has to acquire an annual track to report how the food waste is treated 2007: Revised of Food waste recycling law Co. 2007: 7-11 parent company + Agri Gaia outline turn food waste into animal feedstock 3. 1. 2. Taiwan 2001: EPA starts food waste recycling in government departments 2003: Taipei starts food waste recycling policy 2006: Whole Taiwan (309 towns and townships) carried out food waste collection and recycling 2007: 2007-2012 Public Development Program-General Waste Resource Recycling Promotion Program 3. 1. 2. 4 Singapore 2003: Food from the snapper started the Bread distribution course 2007: IUT + NEA + Veolia collect food waste from markets 3. 1. 2. 5 Hong Kong 40 2009: Food Waste Recycling Partnership Scheme 2011: Food Waste Recycling Projects in Housing EstatesFrom the campaigns and laws mentioned above, we can deduce that Korea, Japan and Taiwan start to re cycle or reuse the food waste in 1995, 2001, 2001 respectively. They start to recycle and reuse the food wastes much earlier than that in Hong Kong although there is a awesome amount of food waste generating every day. Just in 2005, Direct land-filling of food waste was already banned, however, up to now, there is still a large amount of food waste sent to the landfill for dumping. Actually, a a couple of(prenominal) years ago, the approach in compost was already conducted in Korea, Japan and Taiwan. Whereas, Hong Kong uses this technology just in recent years. . 1. 3 Technologies applied in food waste Nowadays most of collected food waste has been recycled to compost and animal feedstuff. A very little part is used in anaerobic digestion. Table 3. 2. Different technologies used in different nations Country Feedstock Composting Anaerobic digestion Others Korea(2005) Japan(2007) Taiwan(2007) Singapore(2008) 54. 4% 50. 0% 77. 6% 75. 5% 29. 7% 45. 0% 21. 8% 2. 4% 1. 4% 5. 0% N. A. 2 2. 0% 14. 4% N. A. 0. 6% 0. 1% Same situation appears in Korea, Japan and Taiwan that they recycle food waste to feed the farm animal at first step and to compost secondly.But the technologies applied in Singapore may be a undersized different that the food waste is delivered to feed livestock and indeed delivered to the anaerobic lagoon. The three different technologies in recycling or reusing the food waste are judged by the following illustrations. 41 3. 1. 3. 1 Food waste composting Composting is one means of reducing the problems associated with landfills, incinerators, and other food waste disposal methods. There are as many different ways to compost as there are people who compost! There are four basic ingredients call for to compost:Oxygen, Water, Carbon (â€Å" brownish material such as wood chips, brown leaves, or shredded newspaper), and Nitrogen (â€Å"Green” wet waste such as grass clippings, or fruit and vegetable scraps from your kitchen). If you have thes e ingredients, you can compost at your home, office, or school. sort 3. 2 shows how food waste flows in a composting way. Figure 3. 2 Food waste flowchart in composting way from http://www. wastereduction. unc. edu/CampusRecycling/FoodWasteComposting. aspx For food wastes compost, there are some benefits and deficiencies in it. Benefits of Compost 42 ? ? Enriches soil, helping curb moisture and suppress plant diseases and pests. Reduces the need for chemical fertilizers. Encourages the production of beneficial bacteria and fungus kingdom that break down organic matter to create humus, a rich nutrient-filled material. ? ? Reduces methane emissions from landfills and lowers your carbon footprint. Compost is a marketable product Besides the illustration above, households, businesses and institutions may save money by composting items such as food scraps while displace less waste to landfills and incinerators.In addition, you can even get the payback from selling compost. Deficiency of Compost: If food waste is not incorporated into the soil it loses atomic number 7 to the atmosphere and may nurse less nitrogen than the compost. Composting requires a time commitment to right manage the windrows to produce quality compost. Specialized windrow turners may be required, but they can come at with a high price tag. The composting site and storage for finished product can use a colossal area of land. Money and time may be spent advertising, packaging, and managing the business. 3. 1. 3. 2 Feed animalsThe eating of food waste or scraps to swine and other livestock animals is a common institutionalise throughout the world and is often concentrated around metropolitan centers. Food plate waste (formerly referred to as garbage) may be fed to other livestock species, but has most often been used as a source of feed for swine. steep disposal costs and fees aid the feeding of food/plate waste. The advantages in applying this measure are listed below: a) It can eli minate a large amount of food waste. 43 b) It can save the feeding cost by replacing the fodder. c) swipe the rates of using resources . 1. 3. 3 Anaerobic digestion If 50 percent of the food waste generated each year in the U. S. was anaerobically digested, enough electricity would be generated to power 2. 5 million homes for a year. With the passing of Halloween, millions of pounds of pumpkins have off-key from seasona l decorations to trash designate for compost heaps or landfills. The story is a critical different in Oakland, California. give thanks to the pioneering work of the East Bay Municipal Utility District (EBMUD), discarded pumpkins and other food waste are used as a source of renewable electricity. How is that possible? number one, waste haulers gather post-consumer food waste and deliver it to EBMUD‘s anaerobic digesters. Inside these giant tanks, bacteria break down the food waste and release methane gas as a byproduct. EBMUD captures this gas and uses it t o generate electricity in onsite generators. A ton of food waste provides about 367 m3 of gas, and digesting 100 tons of food wastes five days a workweek can generate enough electricity to power 1,000 homes. one time the food waste has been digested, the remaining solids make an excellent natural fertilizer, so they can be used to get next year‘s pumpkin crop started.Figure 2. 9 shows how it works. Figure 3. 4. shows how the food waste is recycled or reused in a anaerobic digested way. Firstly, the food waste from industrial, commercial and schools will be collected. And then it will be sent into Centralized Anaerobic Digestion. later on the anaerobic digestion for food waste, it will be converted into two valuable products, renewable ener gy and fertilizer, which is used to supply electric power and in immediately reduce the GHGs from b overleapen fire in the caloric power plant and revise soil respectively. 44 Figure 3. 4 Food waste flowchart in anaerobic digestion w ay.The merits for anaerobic digestion are listed below: a) Generated biogas can be recycled and utilized. It can be used directly as a fuel or for biogas power generation. b) c) Digestion residues (ie, residual sludge) can be used as primary organic fertilizer raw materials. The concentrated sludge dewatering filtrate can be used as plant fertilizer or aquaculture utilization. d) e) f) The odor is easy to control and hard to escape. Compared with the compost product, organics can be more completely and equally composted. The treatment effect is stable and suitable for plan applications. 3. . 4 Barrie rs in food waste recycle/reuse in Hong Kong There is a large capacity of food waste generation in Hong Kong as above mentioned. totally a certain small part is disposed in a Green way and the other part is generally dumped into the landfill. This will not only have an adverse effect on our environment but also cause the resources waste. wherefore 45 does the situation in HK act like this? First of all, the amount of food waste generation in HK is large and larger while EPD is only concentrating in the technologies of food waste recycle/reuse rather than reducing food wastes from the sources.The lack of education in food wastes may be the second reason. Hong Kong is a multi-cultural city with legion(predicate) restaurants. However, the public lacks the excogitation of saving food. In neighbouring countries like Korea and Taiwan, the average out food waste amount per person is 20-30% less. Thirdly, the number of effective policies in Hong Kong introduced to the food waste manage ment is lower than some other countries. A project in Taiwan called ? 2007-2012 Public Development Program-General Waste Resource Recycling Promotion Program? was conducted to achieve proper treatment of all collected food waste and to complement the ?Zero Waste? policy. In Guangzhou, ? Interests draw together system? (????? ) was introduced that residents who were taking an lively part in the garbage classification, take shapers and sanitation workers would earn a certain amount of money according to the benefits of recycled resources. So it really makes a connection betwixt households and garbage classification and encourages people to be more do in protecting our environment. Fourthly, the recent sharp increase of allowance and rent are drag the development o f recycled food wastes. In 2001, EPD promotes a programme called Environment and saving Fund ?Community Waste Recovery Projects? which is attracted by heaps of communities to participate. However, the sharp cost in maintaining the projects almost results in the end of the plans lifetime. Fifthly, the technologies in recycling and reusing the food wastes are not developed very well and many programmes are just on the way. In Japan, TM potentiometer invented ERS (Environmental Recycling form) that is a high-speed Composting (Fermentation & Drying) System which can convert a batch of organic matter or waste into value-added products such as fertilizer or animal feed within 2-24 hours. plot of land in Hong Kong, it normally takes half a calendar month in converting the food wastes 46 to composts. In Sweden, 35% of the recycled food is devoted to be fermented with methane to generate electric power. Last but not least, the majority approaches in recycling the food waste in Hong Kong is composting. The government also encourages the privates to convert the food wastes to composts. However, the composts offered by the privates were hard to be found the markets. Many people who lost their chief city in compost investiture ever are not confident with this technology.In addition, Food waste is always mixed with general waste in the kitchen e. g. plastics, knife, cans etc and food waste barrels is usually too heavy to move. And for most of the hotels and restaurants, additional storage space is needed for food waste. 3. 2 Recommendations The problem of food waste is not only about technical issues such as waste treatment; beyond that, cultural themes like the idea of consumption and human relationship with nature are touch too.Moreover, the solution to it should not be restricted to individual action; government policy and even cultural change should also play a significant role. From two frameworks in reducing food waste in UK and US as references, the suggestions for the solutions enlarge below are in a same order which are shown in Figure 3. 5 and 3. 6. 47 Figure 3. 5 The food waste pyramid from http://www. companyshop. ltd. uk/corporate-social-responsibility/disposal-route. aspx Figure 3. The food waste pyramid from US. http://www. epa. gov/foodrecovery/The government or the organizations faced with food waste should make some public service advertisements about the impacts on the environment, create a website to educate public in food waste reduction and even can organize some activities to enhance the people‘s comprehension of the food wa ste knowledge and famished in other countries. In addition, the society should set up a correct concept for the food consumption. 48 An organization called Food Angel in Hong Kong is working excellent in reducing the food waste from source. It collects food from all segments of food industry which is usually devoted due to some reasons.Then they prepare healthy nutritional meal boxes in their own professional kitchen and finally deliver the meal boxes to individuals and families in need. The government should encourage and reward the organizations like Food Angel who can reduce the food waste from sources. The government should make several effective policies on the food waste. System of rewards and penalties to the charity organizations and commercial companies associated with the food waste should be set up. And more programme on reducing the food waste from sources should be carried out and support to be conducted.In addition, new and high efficiency technologies should be ma de an effort to develop. Furthermore, due to the high cost including premium and the rent for food waste recycling, EPD should give a hand like increase the amount of subsidy to the committee to help them to turn the corner. Generally speaking, in circumstance with the nowadays situation in HK, the experiences from Korea and Japan can be a good example to learn with. We deduce that the food waste recycled in Hong Kong should follow in this order: 1) Feed animals; 2)Used to compost; 3)Deliver to the anaerobic lagoon.The reason for the first one is that the animals can have a good digestion with it and only generate manure rather than leachate or waste residuals. The reason for the second one is that proper compost may content the market and also reduce a certain amount of food waste to be dumped into landfill. The last reason is that after the anaerobic digestion it‘ll generate electric power which can be used by residents and can also reduce the carbon dioxide from coal burni ng in Tsing Yi Power Station. In addition, new and high efficiency technologies should be made an effort to develop.To acquire best cost-efficiency and the lowest impact on the environment, the combination of 3 main technologies in nowadays should be conducted as well. To make the technologies run safely and 49 smoothly, food waste classification should also be in deep consideration. At the meanwhile, people who are certain by EPD may have the right to ticket when they backtrack the classification of the food waste. In the future, we may transform food waste into laundry detergent, plastic ingredients, and a host of everyday products, in a uncovering that may ease compress on the citys bulging landfills.According to the look for made by an environmental scientist at City University of Hong Kong, food waste can be transformed into bioenergy that can be used to generate heat and electricity, and at the same time reduce the volume of food waste destined for landfills by at least 50%. 4 Conclusion While our neighborâ€Koran and Taiwan made an great work in the food waste problem, Hong Kong just started to focus on this kind of problem because of the full- load of landfills by 2018. The collection and recycling strategies applied in recent years may reduce the volume of food waste sent to landfill.But as Hong Kong is one of the largest generation areas of food waste in the world, it is still perplexing whether the recycling rate of food waste can catch up with the present increasing rate of food waste. Therefore, the government should pay more attention on the minimization of food waste and the cooperation with unofficial organization to reduce the generation of food waste in the future. With both the strategies of minimization and reuse/recycling, the food waste prob lems can be solved effectively in Hong Kong.\r\n'