A Look at Personal Beliefs of Teaching

When I was immature, I ne'er had a dream to go a instructor. My instruction besides was non in the instruction field. I had ne'er been learning anyplace before I worked at my university. Therefore, instruction is a new thing for me. When I began to learn, I realized that it was non easy to go a good instructor. It was a large duty. What you teach today could impact person ‘s hereafter. Therefore, as a instructor, I need counsel as my foundation to go a good pedagogue. I believe it is of import that personal beliefs about instruction be explored. This should be an on-going and germinating procedure, because constructing up a personal doctrine of instruction has been a journey of hunt and find. It will turn over the clip based on experiences, and besides on personal and educational developments. The challenges that I will run into during the journey excite new demands to go a better pedagogue. As a instructor, it is my desire to link with my pupils. I believe that instructors should give the pupils attending and affect them in learning and larning procedure. This essay is about my doctrine of instruction. It will be organized as follows: first, I will offer my point of position about the purposes of instruction. Second, I will exemplify my beliefs about instruction and larning methods. Third, I will show my positions about curriculum execution. I will so depict my moralss and morality in instruction and acquisition procedure. I will shut by reasonin g my doctrine of instruction that I mentioned before. My doctrine of instruction starts with what I feel about instruction. For me, the purposes of instruction should include and learn rational, personal, civic, cultural, and moral facets of life. This will guarantee all-around and balanced persons. Education is non merely about developing pupils ‘ minds but besides developing pupils ‘ emotional capacities. Education should make people who care for other people. We do non desire create rational but nescient people. Education should besides concentrate on the civic duties of persons beyond the schoolroom. I think pupils should be encouraged to make out in openness and service to the community beyond the school, to go actively involved in their community. Persons should obtain accomplishments through instruction which contribute to autonomy in work outing jobs of mundane life. I feel pupils should develop regard for the usage, civilizations, and beliefs that occur in our diverse universe. Students should develop values that will be good to the common public assistance of society. In add-on, I feel it besides of import for instruction to encompass plans that develop regard for the environment. Students should acknowledge and aware about their environment and how to use sustainable life. I realize that to accomplish those purposes is a challenge. I hope my doctrine of instruction will assist me and pupils to accomplish them. As a instructor in a distance acquisition university, my focal point is on-line learning. It is a bit different from learning in a â€Å" conventional † or face to face university. I normally have a big on-line category for my class. Sometime it is hard to pay attending to every pupil separately, but I do believe that pupils need attending to do them prosecute with the class. They need to be recognized as an person. So, my doctrine of instruction is a student-centered 1. I believe in concentrating on single demands, and affecting pupils in the procedure of their acquisition. It is my belief that single differences need to be respected. I believe that all pupils have strengths, and that is the end of instruction to help pupils in identifying and edifice upon these. These beliefs are stronger after I have been analyzing at Simon Fraser University ( SFU ) . I see that pupils can larn more if they are engaged with the lessons and with the instructors. Therefore, the lessons have t o be interesting and instructors have to give their best attending to the pupils. I besides believe Freire ‘s ( 1970/2000 ) construct about teacher-student with students-teachers. He argued that â€Å" the instructor is no longer simply the-one-who-teaches, but one who is himself or herself taught in duologue with the pupils, who in bend while being taught besides teach. They become jointly responsible for a procedure in which all grow † ( p. 50 ) . I think it can be employed in distance acquisition university, where most of the pupils are big scholars, and parts of the teaching-learning procedure are based on tutorials. In this method, instructor and pupils have chances to develop treatments, and from those, we can larn from each other. For me, the most meaningful acquisition takes topographic point when pupils are motivated and interested. It is my belief that the manner to accomplish this is by giving pupils a voice in the acquisition procedure, and by helping them in happening connexions in the course of study with their ain life and involvements. By leting pupils to convey their ain narratives, experiences, and thoughts into the schoolroom, we provide the pupils with chances to work together, to larn from each other, and to esteem each others ‘ differences. I besides believe that pupils should be given chances to associate their acquisition and critical thought accomplishments to societal challenges and jobs outside of the schoolroom. Not merely do pupils hold the possible to do a difference within the society, they can turn as persons in the procedure. This attack has the benefits of authorising pupils and constructing their ego regard and job resolution accomplishments. Related with course of study, I believe that establishments and instructors still hold the chief function in developing course of study, and instructors can be flexible in the course of study execution. I learned from my experiences in SFU that pupils could be involved in curriculum execution. They are given a opportunity to give their input, so instructors can place their demands. I believe when instructors give the pupils chances like this, it will do them experience challenged to larn and go more interested and satisfied with the acquisition procedure. Analyzing in a distance acquisition university is non easy. Students have to go self directed-learners. They have to be independent. However, sometime they need to inquire and confer with about their survey troubles with instructors. That is why I besides believe that I should be a good facilitator for my pupils. Not merely should I be a good instructor academically, but besides I should be a usher to my pupils. If there are some inquiries and concerns about their survey, I will assist them exhaustively, administratively and academically. My doctrine besides includes respects, kindness, duty, democratic instruction, forbearance, and clip. Even though pupils and teacher hold different functions, I believe that I, as a instructor, have to handle them with regard, because when we respect each other, the learning acquisition procedure will run swimmingly. I besides have duties to give my pupils a good quality of instruction. Students should derive something utile when they study. In add-on, in my experience, because pupils besides need attending, as a instructor I should be patient and give them my clip for listening. My doctrine of instruction has been shaped by experiences within my ain life and my instruction. I feel that attending every bit good as affecting pupils are of import as parts of the instruction and acquisition procedure. As I enter the profession of instruction, my doctrine may germinate as I gain experiences as a instructor. However, the foundations of my educational doctrine will go on to steer me in the manner which I interact with my pupils.

My reasons for applying for admission to Cerritos College

My father, a CEO of a mid-sized logistics company in South Korea, has always stressed the importance of receiving a good education to me. After graduating from high school he did not to go to college because he wanted to earn by building his own small business, instead of spending money on college tuition.For the first few years, his business seemed to run satisfactorily. However, he had a difficult time in managing his business with the lack of education he received. Whenever he had to make some important decisions in operating business he realized that he was not competent enough to make smart and sound decisions.Eventually, his first small logistics business failed. This was a major turning point for my father. He immediately enrolled in college with a major in Business Administration. After graduating and armed with a degree, my father felt empowered with the education he received and set off to try his hand on fulfilling his goals in business. His present success proves that a c ollege education really makes a difference.My dream is to become a CEO of a company like my father. My father encouraged me to study in the United States, where the quality of education is high and where most of the famous and successful CEOS of big corporations have received their education.For one to dream big, one has to start with small steps. Thus, my short-term goal is to be accepted into  Cerritos College and receive both good grades and experience cultural diversity. My mid-term goal is to transfer to Stanford University after completing  an associate  degree at Cerritos College. Lastly, becoming an influential  CEO of a big company is my long-term goal.Recalling the phrase I read from economy section of the newspaper, â€Å"To become a successful CEO of  a company  the person has to be good at making  decisions, both fast and reasonable decisions†.I  already proved that I have an excellent potential  in becoming a successful CEO of a company  by m aking the right decision and that is  choosing Cerritos College, the ideal place to equip myself with  lots of knowledge and valuable experience which are core requisites for accomplishing my dream.

Data and Computer Communications

DATA AND COMPUTER COMMUNICATIONS Eighth Edition William Stallings Upper Saddle River, New Jersey 07458 Library of Congress Cataloging-in-Publication Data on File Vice President and Editorial Director, ECS: Marcia J. Horton Executive Editor: Tracy Dunkelberger Assistant Editor: Carole Snyder Editorial Assistant: Christianna Lee Executive Managing Editor: Vince O’Brien Managing Editor: Camille Trentacoste Production Editor: Rose Kernan Director of Creative Services: Paul Belfanti Creative Director: Juan Lopez Cover Designer: Bruce Kenselaar Managing Editor,AV Management and Production: Patricia Burns  ©2007 Pearson Education, Inc.Pearson Prentice Hall Pearson Education, Inc. Upper Saddle River, NJ 07458 Art Editor: Gregory Dulles Director, Image Resource Center: Melinda Reo Manager, Rights and Permissions: Zina Arabia Manager,Visual Research: Beth Brenzel Manager, Cover Visual Research and Permissions: Karen Sanatar Manufacturing Manager, ESM: Alexis Heydt-Long Manufacturing B uyer: Lisa McDowell Executive Marketing Manager: Robin O’Brien Marketing Assistant: Mack Patterson All rights reserved. No part of this book may be reproduced in any form or by any means, without permission in writing from the publisher.Pearson Prentice Hallâ„ ¢ is a trademark of Pearson Education, Inc. All other tradmarks or product names are the property of their respective owners. The author and publisher of this book have used their best efforts in preparing this book. These efforts include the development, research, and testing of the theories and programs to determine their effectiveness. The author and publisher make no warranty of any kind, expressed or implied, with regard to these programs or the documentation contained in this book. The author and publisher shall not be liable in any event for incidental or consequential amages in connection with, or arising out of, the furnishing, performance, or use of these programs. Printed in the United States of America 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, Tokyo Pearson Education Malaysia, Pte. Ltd. Pearson Education, Inc. , Upper Saddle River, New Jersey For my scintillating wife ATSWEB SITE FOR DATA AND COMPUTER COMMUNICATIONS, EIGHTH EDITION The Web site at WilliamStallings. com/DCC/DCC8e. html provides support for instructors and students using the book. It includes the following elements. Course Support Materials The course support materials include †¢ Copies of figures from the book in PDF format †¢ A detailed set of course notes in PDF format suitable for student handout or for use as viewgraphs †¢ A set of PowerPoint slides for use as lecture aids †¢ Computer Science Student Support Site: contains a number of links and documents that the student may find useful in his/her ongoing computer science education.The site includes a review of basic, relevant mathematics; advice on research, writing, and doing homework problems; links to computer science research resources, such as report repositories and bibliographies; and other useful links. †¢ An errata sheet for the book, updated at most monthly T DCC Courses The DCC8e Web site includes links to Web sites for courses taught using the book. These sites can provide useful ideas about scheduling and topic ordering, as well as a number of useful handouts and other materials. Useful Web Sites The DCC8e Web site includes links to relevant Web sites, organized by chapter.The links cover a broad spectrum of topics and will enable students to explore timely issues in greater depth. iv WEB SITE FOR DATA AND COMPUTER COMMUNICATIONS, EIGHTH EDITION v Supplemental Documents The DCC8e Web site includes a number of documents that expand on the treatment in the book. Topics include standards organizations, Sockets, TCP/IP checksum, ASCII, and the sampling theorem. Internet Mailing List An Internet mailing list is maintained so that instructors using this book can exchange information, suggestions, and questions with each other and the author.Subscription information is provided at the book’s Web site. Simulation and Modeling Tools The Web site includes links to the cnet Web site and the modeling tools Web site. These packages can be used to analyze and experiment with protocol and network design issues. Each site includes downloadable software and background information. The instructor’s manual includes more information on loading and using the software and suggested student projects. This page intentionally left blank CONTENTS Web Site for Data and Computer Communications Preface xv 1 iv Chapter 0 Reader’s and Instructor’s Guide 0. Outline of the Book 2 0. 2 Roadmap 3 0. 3 Internet and Web Resources 5 0. 4 Standards 6 PART ONE OVERVIEW 9 Chapter 1 Data Communications, Data Networking, and the Internet 10 1. 1 Data Communications and Networking for Today’s Enterprise 12 1. 2 A Communications Model 16 1. 3 Data Communications 19 1. 4 Networks 22 1. 5 The Internet 25 1. 6 An Example Configuration 29 Chapter 2 Protocol Architecture, TCP/IP, and Internet-Based Applications 2. 1 The Need for a Protocol Architecture 33 2. 2 The TCP/IP Protocol Architecture 34 2. 3 The OSI Model 42 2. 4 Standardization within a Protocol Architecture 44 2. Traditional Internet-Based Applications 48 2. 6 Multimedia 48 2. 7 Recommended Reading and Web Sites 53 2. 8 Key Terms, Review Questions, and Problems 54 Appendix 2A The Trivial File Transfer Protocol 57 PART TWO DATA COMMUNICATIONS 62 Chapter 3 Data Transmission 65 3. 1 Concepts and Terminology 67 3. 2 Analog and Digital Data Transmission 78 3. 3 Transmission Impairments 86 3. 4 Channel Capacity 91 3. 5 Recommended Reading and Web Si te 96 3. 6 Key Terms, Review Questions, and Problems Appendix 3A Decibels and Signal Strength 99 Chapter 4 Transmission Media 102 4. Guided Transmission Media 104 4. 2 Wireless Transmission 117 4. 3 Wireless Propagation 125 32 96 vii viii CONTENTS 4. 4 4. 5 4. 6 Line-of-Sight Transmission 129 Recommended Reading and Web Sites 133 Key Terms, Review 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 Reading 175 5. 6 Key Terms, Review Questions, and Problems 175 Chapter 6 Digital Data Communication Techniques 180 6. Asynchronous and Synchronous Transmission 182 6. 2 Types of Errors 186 6. 3 Error Detection 186 6. 4 Error Correction 196 6. 5 Line Configurations 201 6. 6 Recommended Reading 203 6. 7 Key Terms, Review Questions, and Problems 204 Chapter 7 Data Link Control Protocols 207 7. 1 Flow Control 209 7. 2 Error Control 216 7. 3 High-Level Data Link Control (HDLC) 222 7. 4 Recommended Reading 228 7. 5 Key Terms, Review Questions, and Problems 229 Appendix 7A Performance 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 Spread 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 Access 287 9. 5 Recommended Reading and Web Site 290 9. 6 Key Terms, Review Questions, and Problems 291 CONTENTS ix PART THREE WIDE AREA NETWORKS 295 Chapter 10 Circuit Switching 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 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 ATM Logical Connections 331 11. 3 ATM Cells 335 11. 4 Transmission of ATM Cells 340 11. 5 ATM Service 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 Traffic Management 386 13. 4 Congestion Control in Packet-Switching Networks 13. 5 Frame Relay Congestion Control 388 13. 6 ATM Traff ic 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 Generation Analog 427 14. 3 Second Generation CDMA 429 14. 4 Third Generation Systems 437 14. 5 Recommended Reading and Web Sites 440 14. 6 Key Terms, Review Questions, and Problems 441 387 x CONTENTS PART FOUR LOCAL AREA NETWORKS 444 Chapter 15 Local Area Network Overview 446 15. 1 Background 448 15. 2 Topologies and Transmission Media 451 15. 3 LAN Protocol Architecture 457 15. 4 Bridges 465 15. 5 Layer 2 and Layer 3 Switches 473 15. Recommended Reading and Web Site 478 15. 7 Key Terms, Review Questions, and Problems 479 Chapter 16 High-Speed LANs 482 16. 1 The Emergence of High-Speed LANs 483 16. 2 Ethernet 485 16. 3 Fibre Channel 500 16. 4 Recommended Reading and Web Sites 504 16. 5 Key Terms, Review Questions, and Problems 506 Appendix 16A Digital Sig nal Encoding for LANs 508 Appendix 16B Performance Issues 514 Appendix 16C Scrambling 518 Chapter 17 Wireless LANs 522 17. 1 Overview 523 17. 2 Wireless LAN Technology 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 Considerations 549 Recommended Reading and Web Sites 550 17. 7 17. 8 Key Terms, Review Questions, and Problems 551 PART FIVE INTERNET AND TRANSPORT PROTOCOLS Chapter 18 Internetwork Protocols 556 18. 1 Basic Protocol Functions 558 18. 2 Principles of Internetworking 566 18. 3 Internet Protocol Operation 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 TCP 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 SIX Chapter 21 21. 1 21. 2 21. 3 21. 4 21. 5 21. 6 21. 7 21. 8 21. INTERNET 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 Digital 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 Applications—Electronic Mail and Network Managemen t 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 Applications—Internet Directory Service and World Wide 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 Applications—Multimedia 799 24. 1 Audio and Video Compression 800 24. 2 Real-Time Traffic 808 24. 3 Voice Over IP and Multimedia Support—SIP 811 24. 4 Real-Time Transport Protocol (RTP) 820 24. 5 Recommended Reading and Web Sites 831 24. 6 Key Terms, Review Questions, and Problems 832 773 ii CONTENTS APPENDICES 835 Appendix A Fourier Analysis 835 A. 1 Fourier Series Representation of Periodic Signals 836 A. 2 Fourier Transform Representation of Aperiodic Signals 837 A. 3 Recommended Reading 840 Appendix B Projects for Teaching Dat a and Computer Communications B. 1 Practical Exercises 842 B. 2 Sockets Projects 843 B. 3 Ethereal Projects 843 B. 4 Simulation and Modeling Projects 844 B. 5 Performance Modeling 844 B. 6 Research Projects 845 B. 7 Reading/Report Assignments 845 B. 8 Writing 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 Execution 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 International 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 Ones-Complement Addition K. 2 Use in TCP and IP Appendix L TCP/IP Example Appendix M Uniform Resource Locators (URLs) and Uniform Resource Identifiers (URIs) M. 1 Uniform Resource Locator M. 2 Uniform Resource Identifier M. 3 To Learn More Appendix N Glossary Augmented Backus-Naur FormThis page intentionally left blank PREFACE Begin at the beginning and go on till you come to the end; then stop. —Alice in Wonderland, Lewis Carroll OBJECTIVES This book attempts to provide a unified overview 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 piec e, a survey of the state of the art. The book emphasizes basic principles and topics of fundamental importance concerning the technology and architecture of this field and provides a detailed discussion of leading-edge topics.The following basic themes serve to unify the discussion: †¢ Principles: Although the scope of this book is broad, there are a number of basic principles that appear repeatedly as themes and that unify this field. Examples are multiplexing, flow control, and error control. The book highlights these principles and contrasts their application in specific areas of technology. †¢ Design approaches: The book examines alternative approaches to meeting specific communication requirements. †¢ Standards: Standards have come to assume an increasingly important, indeed dominant, role in this field.An understanding of the current status and future direction of technology requires a comprehensive discussion of the related standards. INTENDED AUDIENCE The book is intended for both an academic and a professional 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 used for a one-semester or two-semester course. It covers the material in Networking (NET), a core area in the Information Technology body of knowledge, which is part of the Draft ACM/IEEE/AIS Computing Curricula 2005.The book also covers the material in Computer Networks (CE-NWK), a core area in Computer Engineering 2004 Curriculum Guidelines from the ACM/IEEE Joint Task Force on Computing Curricula. PLAN OF THE TEXT The book is divided into six parts (see Chapter 0): †¢ Overview †¢ Data Communications †¢ Wide Area Networks xv xvi PREFACE †¢ Local Area Networks †¢ Internet and Transport Protocols †¢ Internet Applications In addition, the book includes an extensive glossary, a list of frequently used acronyms, and a bibliography. Each chapter inc ludes problems and suggestions for further reading.The chapters and parts of the book are sufficiently modular to provide a great deal of flexibility in the design of courses. See Chapter 0 for a number of detailed suggestions for both 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 Slides: A set of slides covering all chapters, suitable for use in lecturing. †¢ PDF files: Reproductions of all figures and tables from the book. Projects Manual: Suggested project 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 i nformation for an Internet mailing list for instructors INTERNET SERVICES FOR INSTRUCTORS AND STUDENTS There 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 Communications, preceding the Table of Contents, for more 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 soon as typos or other errors are discovered, an errata list for this book will be available at WilliamStallings. om. PROJECTS AND OTHER STUDENT EXERCISES For many instructors, an important component of a data communications or networking course is a project or set of projects by which the student gets hands-on experience to reinforce concepts from the text. This book provides an unparalleled degree of support for including a projects component in the course. The instructor’s supplement not only includes guidance on how to assign and structure the projects but also includes a set of User’s PREFACE xvii Manuals for various project types plus specific assignments, all written especially for this book.Instructors can assign work in the following areas: †¢ Practical exercises: Using network commands, the student gains experience in network connectivity. †¢ Sockets programming projects: The book is supported by a detailed description of Sockets available at the book’s Web site. The Instructors supplement 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 behavior of protocols. Simulation projects: The student can use the simulation package cnet to analyze network behavior. †¢ Performance modeling projects: Two performance modeling 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 searches. †¢ 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 facilitate learning the material. †¢ Discussion topics: These topics can be used in a classroom, chat room, or message board environment to explore certain areas in greater depth and to foster student collaboration. This diverse set of projects and other student exercises enables the instructor to use t he book as one component in a rich and varied learning experience and to tailor a course plan to meet the specific needs 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 after the publication of the seventh edition. During that time, the pace of change in this field continues unabated. In this new edition, I try to capture these changes while maintaining a broad and comprehensive coverage 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 have 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 substantive changes throughout the book . Every chapter has been revised, new chapters have been added, and the overall organization of the book has changed. Highlights include: †¢ Updated coverage of Gigabit Ethernet and 10-Gbps Ethernet: New details of these standards are provided. †¢ Updated coverage of WiFi/IEEE 802. 11 wireless LANs: IEEE 802. 11 and the related 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 most commercial implementations. †¢ Expanded coverage of security: Chapter 21 is more 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 scheme is now covered. †¢ New coverage of multimedia: Introductory section in Chapter 2; detailed coverage in Chapter 24. Topics covered include video compression, SIP, and RTP. †¢ Online appendices: Fourteen online appendices provide additional detail on important topics in the text, including Sockets programming, queuing models, the Internet checksum, a detailed example of TCP/IP operation, and the BNF grammar.In addition, throughout the book, virtually every topic has been updated to reflect the developments in standards and technology that have occurred since the publication of the seventh edition. ACKNOWLEDGMENTS This new edition has benefited from review by a number of people, 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. Jingxi an Wu (Sonoma State University), G. R.Dattareya (UT Dallas), Guanling Chen (Umass, Lowell), Bob Roohaprvar (Cal State East 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 detailed 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 Southern California provided some homework problems.Thanks also to the following contributors. Zornitza Prodanoff of the University of North Florida prepared the appendix on Sockets programming. Michael Harris of the University of South Florida is responsible for the Ethereal exercises and user’s guide. Lawrie Brown of the Australian Defence Force Academy of the University of New South Wales produc ed the PPT lecture slides. Finally, I would like to thank the many people responsible for the publication of the book, all of whom did their usual excellent job.This includes the staff at Prentice Hall, particularly my editor Tracy Dunkelberger, her assistants Christianna Lee and Carole Snyder, and production manager Rose Kernan. Also, Patricia M. Daly did the copy editing. CHAPTER READER’S AND INSTRUCTOR’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,† demanded Li-loe, â€Å"relate to me the story to which reference has been made, thereby proving the truth of your assertion, and at the same time affording n entertainment of a somewhat exceptional kind. † â€Å"The shadows lengthen,† replied Kai Lung, â€Å"but as the narrative in question is of an inconspicuous span I will raise no barrier against your flatter ing request, especially as it indicates an awakening taste hitherto unexpected. † —Kai Lung’s Golden Hours, Earnest Bramah This book, with its accompanying 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 organized into five parts: Part One. Overview: Provides an introduction to the range of topics covered in the book.This part includes a general overview of data communications and networking and a discussion of protocols, OSI, and the TCP/IP protocol suite. Part Two. Data Communications: Concerned primarily with the exchange of data between two directly connected devices. Within this restricted scope, the key aspects of transmission, interfacing, link control, and multiplexing are examined. Part Three. Wide Area Networks: Examines the internal mechanisms and user-network interfaces that have been developed to support voice, data, and multimedia communications over long-distance ne tworks.The traditional technologies of packet switching and circuit switching are examined, as well as the more recent ATM and wireless WANs. Separate chapters are devoted to routing and congestion control issues that are relevant both to switched data networks and to the Internet. Part 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 key ingredients of a LAN design are explored and specific standardized LAN systems examined.Part Five. Networking Protocols: Explores both the architectural principles and the mechanisms required for the exchange of data among computers, workstations, servers, and other data 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 applications that operate over the Internet. A more detailed, chapte r-by-chapter summary of each part appears at the beginning 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 three different course designs: †¢ Fundamentals of Data Communications: Parts One (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 Parts One (overview), Three (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 possible by eliminating certain chapters that are not essential on a first reading.Chapters that could be optional 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. After reading Part One, the other parts can be read in a number of possible sequences.Figure 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 clear how a given layer of functionality is supporte d from below. There is more material than can be comfortably covered in a single semester, but the book’s organization makes it easy to eliminate some chapters and maintain the bottom-up sequence. Figure 0. 1b suggests one approach to a survey 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 most visible part of the material, the applications, and then seeing, progressively, how each layer is supported by the next layer down. Figure 0. 1c is an example of a comprehensive treatment and Figure 0. 1d is an example of a survey 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 and Transport Protocols Part Six Inter net 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 possible to select chapters to reflect specific teaching objectives 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); Cha pter 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 / INTERNET 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 INTERNET 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 detailed description of that site. As soo n 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 computer science students and professionals.Links and documents are organized into four categories: †¢ Math: Includes a basic math refresher, a queuing analysis primer, a number system primer, and links to numerous math sites †¢ How-to: Advice and guidance for solving homework problems, writing technical reports, and preparing technical presentations †¢ Research resources: Links to important collections of papers, technical reports, and bibliographies †¢ Miscellaneous: A variety of useful documents and links Other Web Sites There are numerous Web sites that provide informa tion 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 thousands of hardware and software vendors who currently have Web sites, as well as a list of thousands of computer and networking companies in a phone directory. †¢ IEEE Communications Society: 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. †¢ International Telecommunications Union: Contains a listing of ITU-T recommendations, plus information on obtaining ITU-T documents in hard copy or on DVD. †¢ 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 bit hard to navigate, but worthwhile. USENET Newsgroups A number of USENET newsgroups are devoted to some aspect of data communications, networks, and protocols.As with virtually all USENET groups, there is a high noise-to-signal ratio, but it is worth experimenting to see if any meet your needs. The most relevant are as follows: †¢ comp. dcom. lans, comp. dcom. lans. misc: General discussions of LANs †¢ comp. dcom. lans. ethernet: Covers Ethernet, Ethernet-like systems, 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-management: Discussion of network management applications, protocols, and standards †¢ comp. rotocols. tcp-ip: The TCP/IP protocol suite 0. 4 STANDARDS It has long been accepted in the telecommunications industry that standards are required to govern the physical, electrical, 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 communicate 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 must communicate with each other and, with the ongoing evolution of protocol standards, customers will no longer accept special-purpose protocol conversion software development. The result is that standards now permeate 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 most 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. Thi s 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 recent years the various standards-making organizations have begun to cooperate more closely. Nevertheless, there are still areas where multiple conflicting standards exist.Throughout this book, we describe the most important standards in use or being developed for various aspects of data and computer commun ications. Various organizations have been involved in the development or promotion of these standards. The following are the most important (in the current context) of these organizations: †¢ Internet Society: The Internet SOCiety (ISOC) is a professional membership society with more than 150 organizational and 6000 individual 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 Task Force (IETF) and the Internet Architecture Board (IAB).All of the RFCs and Internet standards are developed through these organizations. †¢ IEEE 802: The IEEE (Institute of Electrical and Electronics Engineers) 802 LAN/MAN Standards Committee develops local area network standards and metropolitan area network standards. The most widely used standards are for the Ethernet family, wireless LAN, bridging, a nd 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 international 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 Forum: The ATM Forum is an international nonprofit organization formed with the objective of accelerating the use of ATM (asynchronous transfer mode) products and services through a rapid convergence of interoperability 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 bod ies from more than 140 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 published 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, meaning equal. PART ONE Overview The purpose of Part One is to provide a background and context for the remainder of this book. The broad range of topics that are encompassed in the field of data and computer communications is introduced, and the fundamental concepts of protocols and protocol architectures are examined.ROAD MAP FOR PART ONE Chapter 1 Data Communicati ons, Data Networks, and The Internet Chapter 1 provides an overview of Parts Two through Four of the book, giving the â€Å"big picture. † 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 exactly 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 reliable and efficient manner. Topics covered include signal transmission, transmission media, signal encoding, 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 1980s 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 revolution 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 these trends has been a growing overlap of the computer and communications industries, from component fabrication to system integration. Another resul t 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 driving 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. Then 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, AND THE INTERNET 1. 1 DATA COMMUNICATIONS AND NETWORKING FOR TODAY’S ENTERPRISE Effective and efficient data communication and networking facilitie s are vital to any enterprise. In this section, we first look at trends that are increasing the challenge for the business manager in planning and managing such facilities. Then we look specifically at the requirement for ever-greater transmission speeds and network capacity. TrendsThree different forces have consistently driven the architecture and evolution of data communications and networking facilities: traffic growth, development of new services, and advances in technology. Communication traffic, 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 emphasis on office 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 minimize transmission costs. As businesses rely more and more on information technology, the range of services expand s. This increases the demand for high-capacity networking and transmission facilities.In turn, the continuing growth in high-speed network offerings with the continuing drop in prices encourages the expansion of services. Thus, growth in services and growth in traffic capacity go hand in hand. Figure 1. 1 gives some examples of information-based services and the data rates needed 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 capable of supporting more demanding applications, such as multimedia applications.In terms of communications, the increasing use of optical fiber has brought transmission prices down and greatly increased capacity. For example, for long-d istance telecommunication and data network links, recent offerings of dense 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, such as the public switched telephone network (PSTN), and data networks, including the Internet, are more â€Å"intelligent† than ever. Two areas of intelligence are noteworthy.First, today’s networks can offer differing levels of quality of service (QoS), which include specifications for maximum delay, minimum 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 Messaging/text apps Voice Location services Still image t ransfers Internet/VPN access Database access Enhanced Web surfing Low-quality video Hifi audio Large file transfer Moderate video Interactive entertainment High-quality video Performance: Poor Adequate 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 personal 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 free from unwanted 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.T he 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 changes in the way organizations do business and process information have been driven 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 cycli c dependency: the availability of new image-based services on the Internet (i. e. , the Web) has resulted in an increase in the total number of users and the traffic volume generated by each user. This, in turn, has resulted in a need to increase the speed and efficiency 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 business WAN requirements. Finally we offer a few words about the effect of changes in commercial electronics on network requirements. The Emergence of High-Speed LANs Personal computers and microcomputer workstations began to achieve widespread acceptance in business computing in the early 1980s and have now achieved virtu ally the status of the telephone: an essential tool for office workers.Until relatively recently, office LANs provided basic connectivity services—connecting personal computers and terminals to mainframes and midrange systems that ran corporate 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 token 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 enjoy explosive growth. These more powerful platforms support graphics-intensive applications and ever more elaborate graphical user interfaces to the operating system. . MIS (management information systems) organizations hav e recognized the LAN as a viable and essential computing platform, resulting in the focus on network computing. This trend began with client/server computing, which has become 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 16-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: †¢ Centralized server farms: In many applications, there is a need for user, or client, systems to be able to draw huge amounts of data from multiple centralized 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 typically 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 draw 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-speed 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 ear ly 1990s, there was an emphasis in many organizations on a centralized data processing model.In a typical environment, there might be significant computing facilities at a few regional offices, consisting of mainframes or well-equipped midrange systems. These centralized facilities could handle most corporate applications, including basic finance, accounting, and personnel programs, as well as many of the business-specific applications. Smaller, outlying 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. This model began to change in the early 1990s, and the change accelerated through the mid-1990s. Many 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 funda mentally 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 load has risen. All of these trends means that more data must be transported off premises and into the wide area. It has long been accepted that in the typical business environment, about 80% of the traffic remains 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 [COHE 96]. 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 (DVDs) 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 analog 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 di gital age. It delivers movies with picture quality that outshines laser disks, and it can be randomly 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 storage 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 digital 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 simple 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: †¢ Source.This device generates the data to be transmitted; examples are telephones and personal computers. Source system Destination system Source Transmitter 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 somewhat arbitrary: Elements could be added; items on the list could be merged; and some items repr esent several tasks that are performed at different â€Å"levels† of the system. However, the list as it stands is suggestive 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 Recovery 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 arrive 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 ringing 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 data 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

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Current Events discussion in the Technology or Security Arena - Assignment Example Meanwhile, the Pentagon reported that no sensitive information was on the social site. US authorities affirmed that no classified information is ever posted on the social site. Authorities also confirmed that the hackers did nothing much except to take control of the Megaphone (Clarion Project 1). The incident lasted for 40 minutes, during which the ISIS bragged and issued threat the best way it could. The fact that computer systems can be hacked remotely is not a new phenomenon except that it is a big question which system is hacked. Online companies have found themselves dragged into wars that many of them are hardly prepared. The fact that many social websites allow users to post on their walls or those of others, it seems that a security breach portal is always open for manipulation. That implies that such limited permission encryption for posting on another user’s wall can be de-encrypted in part for hacking. In a related incident, the problem of system security, particularly cyber security, is now being treated with the seriousness it deserves. Governments have realized that as long as they are going to use some of the services offered by social media, the have to protect them. Such protection may imply formulating new laws that regulate what is to be released to the public. While responding to questions, Cameron hinted that given the present of terrorism, it is important that governments wake up to the realization that the digital era requires monitoring of communications (Horsley 1). The specific security question that came out was the observation that social media companies, for instance, Facebook and Google, are offering high-tech encryption technology. Cameron observes that by offering unbreakable codes, social media companies are putting security of citizens in risk. That is because terrorists can manipulate such codes for

Career Action Plan and Self Reflection Essay Example | Topics and Well Written Essays - 1250 words

Career Action Plan and Self Reflection - Essay Example anagement Trainee before he/she can become a Department Manager, a Senior Department manager, an Assistant Store Manager, and finally a Store Manager (Primark, 2013a). To qualify as a Store Manager, the key competencies for the job includes hands-on experiences on how to manage a retail store outlet (i.e. sales floor, merchandising, cash office, stock room training, and HR management), good leadership skills, knowledge on health and safety issues, policies and procedures as well as consumer and employee legislations (Primark, 2013a). Considering the key competencies needed in becoming a Store Manager, this report will give me the opportunity to undergo the process of self-evaluation. Using the first report assignment as a basis of my self-evaluation, I will present a personal analysis, gap analysis, career action plan, and CV preparation in this report. Prior to conclusion, a self-reflection with regards to the development of my team working skills will be provided in details. Because of my past and current work experiences, I believe that I have strong skills, knowledge, and experiences not only when it comes to dealing with customer concerns but also in terms of managing people. Since August 2010 up to November 2011, I was working as a sales assistant in one of Nike’s retail store outlets in London. Working with this company has definitely taught me a lot about how the retail industry works. Since I used most of my time dealing with customers in trying to find out what exactly they need in a pair shoes, I realized that most of their choices are highly dependent not only on the quality of shoes but also in terms of its performance and fashion design. Between January 2011 up to August 2012, I was employed by FNOT Cars. With this company, I was able to enhance further my ability to deal with different customers each day. The fact that I was given the responsibility to assign tasks to some drivers somehow improves my leadership and communication skil ls. (See

FINANCIAL SERVICES MARKETING Assignment Example | Topics and Well Written Essays - 2500 words

FINANCIAL SERVICES MARKETING - Assignment Example SWOT Analysis SWOT analysis of an organization is its strength, weakness, opportunity and threat analysis. Through strengths and weaknesses are generally considered internal to the organization whereas opportunities and threats are mainly external to the organizations like change in environmental factors or change in governmental regulations. SWOT analysis inculcates new ideas in strategic planning of the organization and can help any organization to take advantage of its strengths and defend against weaknesses. It is easier to conduct and does not incur high costs. It helps organizations to be aware of its external threats, mainly political and environmental threats. So this helps and organization to get prepared for them beforehand (Keller, 2009). SWOT analysis of SBNY is as follows: Strengths SBNY’s concentration in the New York metropolitan area deters it to reap the benefits of a diverse geographic presence (SBNY Annual Report, 2010). ... Therefore, any adversity in the economy of the area would hamper company’s earnings. As it is an investment banking company and a Financial institution its customers ranges from retail investors to the companies for which it does merchant banking and underwriting business. The company has fixed a lower limit of investments at which it starts managing the portfolio of its customers. This is done generally to create a standard lot of investment for all the retail investors. The lower limit is decided based upon the marker scenario. The funds of SBNY are managed under a separate wing known as SBNY Fund Management ltd, which is a subsidiary of SBNY (SBNY Annual Report, 2010). SBNYFM is currently operating on the institutional platform and its fund accounting and investment staff provides best class services to its clients. The fund management services are provided mainly to small and large retail investors. The next level services provided to the companies are Corporate Financial Services. It includes Initial Public Offerings, Corporate M&A, and Financial Advisory and capital market services. SBNY’s organizational structure provides for the establishment of private client groups, where each group caters to all the banking needs of its clients. The members of such group are highly experienced as they are recruited from major New York banks and brokerages with 20 years of experience in financial services, and are in position to serve the clients in best possible way. A typical group director has an established team of two to four additional professionals to assist with business development and client services. SBNY has 71 teams headed by 92 group directors. The company has projected to hire 11 more teams (About

Microenomomic Essay Example | Topics and Well Written Essays - 3000 words

Microenomomic - Essay Example If we consider an office style or look during 1986 to 1996 we can find a very large great development. Offices in those days were not having air conditioners, highly glazed tiles and never use to consider to place an office in the posh localities of the city. The ideology of having an office was to a business in a marked place where potential consumers throng at a particular place. So having a shop or an office at that place was enough. So this was the primary reason why office development was not so significant during the decade. Considering an in-depth analysis as to why an office development is needed. If a business done by that office is very sophisticated, to the tune of lakhs and crores of money, or if the business demands such high class office. Only there we can say that there will be a significant development in the office layout or the structure. The above conditions were considered only during that decade 1986-1996. That was the mindset of people in those days. Considering from the year 1986 there were no business which were very sophisticated only some of the business like car dealer show rooms or a photo studios were to be very tastefully established even here also there is a reason behind the offices to be so classy. The money involved behind the car and photo studio business was very high compared to the other businesses. Even today if we see car and studio business make large business then many small business. From the above examples it is clear then office development is directly related to the money involved. Office development activity was concluded t be very show process since it would involve money and time and also down time for several business applications. Even renovations take time. But the need for office development comes with its demand for posh office. During the percent of the population residing I rented homes. Every other person use to have their own home. While setting up an office, land value was not at all a constraining factor for the businessmen. After the death of the great Indian leaders Mrs.Indira Ghandi made many restrictions put by her were removed by her son Rajiv Ghand paved a way to a new beginning to a developed living and well-being. Real estates business was almost nil in the first decade. The primary potential of business in India being agriculture, the land values were very low. The traders and dealers who were to buy crops from the farmers and small peasants and who were situated in cities were to have nicely decorated offices and large go downs. More ove r the advanced material required to construct posh offices were not available at that time in the Indian market. Offices those days were but and decorated with whatever material was available in local market. Behind every activity there comes the need were there was not necessity too hence state of the art offices It was only after the then Prime Minister Rajiv Ghandhi lifted the sanctions in 1988 put by Indira Ghandi . The multi national company started the operations soon after the sanctions were lifted. This slowly stated the development of particular fields like information technology and telecom etc. This was a major revolution as far as development corporate sector was considered. As I have mentioned earlier there should be a need for any activity, IT and Telecom were the key reasons behind the developmental activity which involved

Construction law Essay Example | Topics and Well Written Essays - 1500 words

Construction law - Essay Example 2. This paper will look into the value for money delivered by PFI methods in order to determine if PFI is preferable in comparison to public funding. Synopsis of PFI 3. The PFI method relies on delivering infrastructure and / or services for the general public through the utilisation of private funds and resources. The provision is kept in line using public sector specifications so the public sector can be seen as exerting sizable influence on the overall process. Typically the private sector’s involvement is largely directed to financial support for public projects as per the PFI approach. However, the private sector can also be involved in the operation and maintenance of services that might have been built using PFI or other previous methods3. The basic contention behind PFI is to allow the private sector greater involvement in public spending projects so that the burden on the public sector is eased. Moreover, the involvement of the private sector ensures that public secto r projects are competitive enough while delivering optimal value for money goods and services. Advantages and Disadvantages of PFI Successful PFI Implementations 4. Advocates of PFI argue that projects implemented under the PFI arrangement show greater promise than conventionally public sector funded projects. Research indicates that conventional public infrastructure provision arrangements provided on time and on budget projects around 30% and 27% respectively. In contrast, PFI arrangements provided an increase of 76% and 78% for on time and on budget project handovers4. These statistics clearly highlight that PFI has the capacity to deliver better both in terms of budget variances and schedule variances. The inherent nature of the private sector makes it competitive since the public sector has little or no other competition for infrastructure and service delivery. It is often common that the public sector tends to see negative budget and negative schedule variances on projects sin ce no other benchmarks are possible. However, the private sector thrives on competition and escalating negative budgetary and negative scheduling variances indicate a failing business strategy. The need to remain relevant to the market ensures that private businesses are more efficient in terms of resource and time utilisation when compared to the public sector. 5. Similarly, other research into PFI arrangements showed that optimised deals were attained in every case studied. Moreover, research findings indicated that value for money in PFI projects was achieved 80% of the time5. Another notable aspect of PFI initiatives is the decrease in costs since private financers are looking for ways to reduce costs. Research indicates that public infrastructure provision becomes between 7% and 23% cheaper when PFI methods are applied6. Other research placed cost reduction at 11%7. It could be reasoned that cheaper infrastructure and service provision would lead to a lower quality. However, it must be noted from the research above that value for money is achieved in 80% of PFI projects which tends to dispel this method of reasoning. 6. Critics of the PFI approach contend that private involvement tends to make infrastructure and service provision too competitive such that value addition is minimised. However, such claims hold little ground in light

Critical Book Review Research Paper Example | Topics and Well Written Essays - 1500 words - 1

Critical Book Review - Research Paper Example He uses personal experience as the chairman of the council of economic advisors under the presidency of bill Clinton from the year 1993 and as the chief economist at the World Bank from 1997 to make his arguments. During this period, Stiglitz became disenchanted with the International Monetary Fund and other international institutions which he regarded as acting against the interests of the poor developing countries in favor of the developed world. He argues that the economic policies of the International Monetary Fund are based on unsound neoliberal assumptions that are only beneficial to the developed economies. The main precept of the book is that pro-globalization policies have the potential of benefitting all countries if properly undertaken and properly incorporated into the individual characteristics of each particular country. Otherwise the objectives of globalization will not be realized as it will only continue to serve the interests of the developed world leaving the developing countries lagging behind in all aspects. Globalization should therefore be embraced by all countries on their own unique terms. These countries should consider their own culture, history, and traditions while embracing globalization in order to ensure that it doesn’t work against them. The adoption of poorly designed or emulated pro-globalization policies often has the effect of being costly to the concerned countries. The resultant effect is increase in the levels of instability which renders such countries more susceptible to reduced growth, external shocks and increase in the levels of poverty. He goes on to argue that globalization has not been fairly pushed to benefit all because the policies of liberalization were haphazardly implemented in the wrong order using inadequate and at times wrong economic principles. The consequences of this as he has pointed out is that terrible results are now being felt including

Definition of art Essay Example for Free

Definition of art Essay A number of people have asked about the value of addressing aesthetics, the philosophy of art, or the definition of art. The reasoning is that if it is so difficult to define, it must therefor be ultimately subjective, and each person should just determine for herself what it is. Perhaps we all do determine for ourselves the meaning of anything. Because, as in the tree falling in the forest example, the meaning does not exist if it does not exist for me personally. I am allowed to define table or chair any way I wish for myself, but if I hope to communicate with others about tables and chairs, the meaning or definition must be shared. And that shared meaning derives from a combination of (a) acquired meanings from those whom we give credibility and (b) connotations developed from our experiences with tables and chairs. If there were really no way to define art, there would be no way to determine what is art, and art could be anything. Fortunately, art can be defined, although not succinctly in verbal form, as we might define table or chair. We learn the definition indirectly through understanding why works have been labeled art by critics and artists in the past, and directly by understanding the perspectives of those critics and artists. From the standpoint of complete subjectivity, if art can be anything, it is meaningless as a term == art is everything and nothing. There is nothing that is not art, so everything is art. The term art has no shared meaning and has no value in communication, and yet we use it all the time. By what criteria do you determine what is art for yourself? Because it pleases you? Because it pleases your friends, or someone you respect, or most people around you? What criteria constitute pleasing? What does it do to please? From another perspective, other than pragmatic needs, by what criteria do we select a season? Or what material we place in museums? By what criteria do we judge quality? How do we determine good from not good? Whatever criteria we use become our criteria for our aesthetic, which then become, in fact, our definition of our art. It is useful and valid for us to question what those criteria are, to challenge the validity of those criteria, and to constantly explore new criteria to define the art experience. In order to comprehend the options of criteria, the kinds of questions to ask of our criteria, the possible limits of our personal vision, it is worthwhile to explore the explorations of others. Understand that the definition of art and the determination of quality are linked and mutually affected. Alter one and the other is changed. One additional concern is the value in trying to understand how art works have meaning. Once we begin to explore this as artists, our work instantly changes dimension. It moves from the surface to the soul and allows us to refocus on the meaningful.

Roles of Culture in Organizations Essay Example for Free

Roles of Culture in Organizations Essay Whats the role of culture in modern corporations and how can it be managed effectively? People in every workplace talk about organizational culture and that mysterious word that characterizes a work environment. One of the key questions and assessments, when employers interview a prospective employee, explores whether the candidate is a good cultural fit. Culture is difficult to define, but you generally know when you have found an employee who appears to fit your culture. He just feels right. Culture is the environment that surrounds you at work all of the time. Culture is a powerful element that shapes your work enjoyment, your work relationships, and your work processes. But, culture is something that you cannot actually see, except through its physical manifestations in your work place. There are so many different definitions of culture in the past by many scholars in the past. The variety of meaning is so diverse that it is impossible to offer any value as a research topic. Culture seeks to describe those facets of human experience that contribute the differences and similarities in how people perceive and engage with their world. We define organizational culture as a set of shared, often implicit assumptions, beliefs, values and sense-making procedures that influences and guides the behavior and thinking of organizational members, and continuously enacted and in turn reinforced –or changed- by the behavior of organizational members. Our definitions is fully compatible three characteristics universally seen as central to the concept of culture: (a) it emerges during the adaptive interaction between people and their environment, and therefore it will change when these interactions change; (b) it is by necessity constituted only of shared, intersubjective elements; and (c) it is transmitted to members across time periods and changing member cohorts or generations. In many ways, culture is like personality. In a person, the personality is made up of the values, beliefs, underlying assumptions, interests, experiences, upbringing, and habits that create a person’s behavior. Culture is made up of the values, beliefs, underlying assumptions, attitudes, and behaviors shared by a group of people. Culture is the behavior that results when a group arrives at a set of rules (generally unspoken and unwritten) for working together. An organization’s culture is made up of all of the life experiences each employee brings to the organization. Culture is especially influenced by the organization’s founder, executives, and other managerial staff because of their role in decision making and strategic direction. Edger Schein’s (1985) three levels of culture: artifacts, values and assumptions. For Schein, the essence of culture is located at the level of basic assumptions which reflect how members of culture experience reality, how they perceive the physical and social world, and how they think and feel. These assumptions are taken for granted, and rarely questioned. A culture’s assumptions provide the basis for and interact with values –Schein’s next level of culture. Values are the social norms, principles, standards and objectives that are valued by cultural members for their intrinsic worth. Values are accessible because they are revealed by behavior and priorities. Cultural values often indicate what is seen as morally right and wrong in a particular context. Even though values remain subconscious, members are more aware of them than of their underlying cultural assumptions. In particular, members become aware of their values when they are challenged during times of change or when someone violates conventions. Values are linked to artifacts, Schein’s third cultural level, in that values-congruous behaviors express and manifest the cultural values and assumptions located at the other levels. This can happen through deliberate expressive actions, through unintended expressive actions, or through other actions that manifest cultural assumptions and values. Anything observable linked to behavior can be seen as artifacts including objects, verbal expressions and activities. But how culture effect on organizations? The culture of a country or region in which the organizations function influences the way of motivating employees. In some countries, such as Japan, giving an individual reward to an employee could embarrass the recipient and so be de-motivating. In high-context collective cultures, there are often expected norms of behavior for particular situations. Offering rewards for individual behavior that runs counter to group norms is unlikely to have a positive influence on motivation. In some countries, the perception of material items is as gifts rather than as rewards for performance. In China, for example, organizations often distribute food to all employees as holiday gifts. People in higher position positions get more or better quality items, but employees make no connection between their performance and the gifts. People in different cultures communicate among themselves differently. The major differences in how people from different cultures communicate with each other are language usage, verbal style, and nonverbal communication. Two people may speak the same language but speak it quite differently. Verbal communication styles are another way for cultures to vary in their communication patterns. In cultures employing a direct style, the speaker tries to convey his true feelings through the choice of words. In the indirect style, the speaker selects words to hide his real feelings. The direct style is common in individualistic, low-context cultures, and the indirect style in collective, high-context cultures. The direct style allows the individualist to express his own ideas clearly. The collective orientation is to maintain group harmony and concern for the feelings of others. There is a number of effects of culture on organization and making a diverse multi-cultural organization must be a great challenge to the managers, but there are also advantages of managing organizational culture. There are seven characteristics of culture which can help managers to manage the culture more effectively. (www.about.com ) †¢ Culture = Behavior. Culture is a word used to describe the behaviors that represent the general operating norms in your environment. Culture is not usually defined as good or bad, although aspects of your culture likely support your progress and success and other aspects impede your progress. A norm of accountability will help make your organization successful. A norm of spectacular customer service will sell your products and engage your employees. Tolerating poor performance or exhibiting a lack of discipline to maintain established processes and systems will interrupt your success. †¢ Culture is learned. People learn to perform certain behaviors through either the rewards or negative consequences that follow their behavior. When a behavior is rewarded, it is repeated and the association eventually becomes part of the culture. A simple praise from an executive for work performed in a particular manner molds the culture. †¢ Culture is learned Through Interaction. Employees learn culture by interacting with other employees. Most behaviors and rewards in organizations involve other employees. An applicant experiences a sense of your culture, and his or her fit within your culture, during the interview process. An initial opinion of your culture can be formed as early as the first phone call from the Human Resources department. †¢ Sub-cultures Form through Rewards. Employees have many different wants and needs. Sometimes employees value rewards that are not associated with the behaviors desired by managers for the overall company. This is often how subcultures are formed, as people get social rewards from coworkers or have their most important needs met in their departments or project teams. †¢ People Shape the Culture. Personalities and experiences of employees create the culture of an organization. For example, if most of the people in an organization are very outgoing, the culture is likely to be open and sociable. If many artifacts showing the company’s history and values are in evidence throughout the company, people value their history and culture. If negativity about supervision and the company is widespread and complained about by employees, a culture of negativity, that is difficult to overcome, will take hold. †¢ Culture is negotiated. One person cannot create a culture alone. Employees must try to change the direction, the work environment, the way of work is performed, or the manner in which decisions are made within the general norms of the workplace. Culture change is a process of give and take by all members of an organization. Formalizing strategic direction, systems development, and establishing measurements must be owned by the group responsible for them. Otherwise, employees will not own them. †¢ Culture is Difficult to Change. Culture change requires people to change their behaviors. It is often difficult for people to unlearn their old way of doing things, and to start performing the new behaviors consistently. Persistence, discipline, employee involvement, kindness and understanding, organization development work, and training can assist you to change a culture. Your work culture is often interpreted differently by diverse employees. Other events in people’s lives affect how they act and interact at work too. Although an organization has a common culture, each person may see that culture from a different perspective. Additionally, your employees’ individual work experiences, departments, and teams may view the culture differently. Your culture may be strong or weak. When your work culture is strong, most people in the group agree on the culture. When your work culture is weak, people do not agree on the culture. Sometimes a weak organizational culture can be the result of many subcultures, or the shared values, assumptions, and behaviors of a subset of the organization. For example, the culture of your company as a whole might be weak and very difficult to characterize because there are so many subcultures. Each department or work cell may have its own culture. Within departments, the staff and managers may each have their own culture. Ideally, organizational culture supports a positive, productive environment. Happy employees are not necessarily productive employees. Productive employees are not necessarily happy employees. It is important to find aspects of the culture that will support each of these qualities for your employees. Managers must know well how to manage the organization’s culture and have to explore many aspects of organizational culture and cultural change to make organization more effective and productive. The concept of culture will become useful for the managers to make successful and productive organization by managing culture effectively. Managing culture is very much concerned with leadership of a manager. Culture is a difficult to define concept and is capable of being misinterpreted by managers who must attempt to make use of it in their work activities. A range of definitions were explored, as were number of facets of both organizational and national culture relevant to the human experience of work. New employees must be effectively integrated into the organization if they are to become productive members. It is not possible to manage every person all the time that they are at work. Internalization of responsibility and knowledge of requirements must be delegated if effective management is to be achieved. Culture is able to offer a meaningful way of accounting for many related phenomena. However, the notion of culture, particularly a strong culture, however attractive, provides a conflict-free way for managers to ensure harmony and the achievement of objectives, is simplistic and does not reflect experience. Culture is a problematic concept because it is difficult to define in precise terms. It is an easy term to recognize in that it is relatively obvious how organizations differ. When visiting an organization, a ‘feeling’ becomes apparent which provides a general indication of the culture. For example, one organization might feel busy with a buzz of activity and a feeling of purpose; while another might feel relaxed with a feeling of calmness in the approach to work. It is important for managers to study other cultures also because their competitors, suppliers, shareholders, or employees may come from other cultures. In developed countries there is also an increasing number of immigrants and workers bringing their own cultures into their new homes. Managers have to be able to integrate them into the new work environment. Hence, it is necessary for managers to know their culture as well as to understand their way of life. References i. â€Å"Organizational behavior management, by John Martin fellenz.† Publisher â€Å"South- Western† ii. â€Å"Organizational behavior-an experiential approach, by Joyce S, David A, Irwin M, and Marlene E.† Publisher â€Å"Pearson† iii. www.about.com iv. www.biomedcentral.com v. www.attractorconsulting.com vi. www.academia.edu