Data communications and enterprise networking Volume 1

1 data communications andenterprise networking Volume 1P. T a r rCO22222005 Undergraduate study in Computing and related programmesThis is an extract from a subject guide for an undergraduate course offered as part of the University of London International Programmes in Computing. Materials for these programmes are developed by academics at more information, see: guide was prepared for the University of London International Programmes by:P. TarrThis is one of a series of subject guides published by the University. We regret that due to pressure of work the author is unable to enter into any correspondence relating to, or arising from, the guide.

2 If you have any comments on this subject guide, favourable or unfavourable, please use the form at the back of this of London International Programmes Publications Office 32 Russell Square London WC1B 5DN United Kingdom by: University of London University of London 2005 The University of London asserts copyright over all material in this subject guide except where otherwise indicated. All rights reserved. No part of this work may be reproduced in any form, or by any means, without permission in writing from the publisher. We make every effort to respect copyright. If you think we have inadvertently used your copyright material, please let us Aims and objectives Learning outcomes Course outline How to use this subject guide Reading list Useful web links Study time Examination 4 Chapter 2.

3 Basic concepts 5 Introduction 5 Further reading data communications Shannon s communication Model Channels Networks 12 Specimen examination question 16 Learning outcomes 16 Chapter 3: Network architecture 17 Introduction 17 Further reading Layered architectures Reference models Network standards Network devices Network protocols 23 Specimen examination question 27 Learning outcomes 28 Chapter 4: The application layer 29 Introduction 29 Further reading Services Interfaces Functions Virtual terminal protocols (Telnet, SSH and VT) Web protocols (HTTP and HTML) Mail protocols (SMTP, MIME, POP, IMAP and MOTIS) File transfer and access protocols (FTP, TFTP, NFS and FTAM) Directory protocols (DNS, and LDAP) Network Management Protocols (SNMP and CMIP) 43 Specimen examination question 44 Learning outcomes 45 Chapter 5.

4 The transport layer 47 Introduction 47 Further reading Services Interfaces Functions User Datagram Protocol (UDP)4 Transmission Control Protocol (TCP) Sequenced Packet Exchange (SPX) Transport Layer Security (TLS) 58 Specimen examination question 60 Learning outcomes 60 Chapter 6: The network layer 61 Introduction 61 Further reading Services Interfaces Functions Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) Internet Group Management Protocol (IGMP) IP Security Protocols (IPsec) Address Resolution Protocols (ARP19 and RARP20) Internet Protocol Version 6 (IPv6) ICMP Version 6 (ICMPv6)77 Specimen examination question 77 Learning outcomes 77 Chapter 7.

5 The data link layer 79 Further reading Services Interfaces Functions Binary Synchronous communications (BSC or BiSync) High-level data Link Control (HDLC) Point-to-Point Protocol (PPP) Logical Link Control (LLC) Ethernet Media Access Control (IEEE )17 95 Specimen examination question 96 Learning outcomes 96 Chapter 8: The physical layer 97 Introduction 97 Further reading Services Interfaces Functions Dial-up modems Digital Subscriber Line (DSL) Cable modems 115 Specimen examination question 116 Learning outcomes 116 Appendix A 117 Specimen examination paper 117 Appendix B 119 Model answers and hints 119A: Specimen examination paper 122 Appendix C 125 List of acronyms 125 Comment form 130 data communications and enterprise networksChapter 1.

6 Aims and objectivesThe CIS222 module aims to provide you with a good grounding in datacommunications and enterprise networking . It is a level two course, buildingon material taught in level one modules. The course concentrates on breadthof understanding rather than depth, and attempts to cover a wide range ofnetworking topics by means of a structured high-level approach. If you desirea deeper understanding of any of the topics covered in this subject guide, youshould refer to the recommended have become increasingly important in recent years. Hardly anyapplications are now stand-alone. Most applications communicate over anetwork, either between a client PC and a server in the same building over aLocal Area Network or between computers in different cities, countries orcontinents over a Wide Area Network.

7 The study of networks andapplications that make use of networks is now an important part of anyundergraduate computer science programme. An understanding of hownetworks operate will be useful in any computing career you may choose tofollow. The main objective is for you to build a logical framework in whichnetworking topics can be studied, analysed and understood. This will standyou in good stead if you subsequently work in the computer or networkingindustry and have to design, develop or manage systems that make use ofnetworks. This subject, like many in Computer Science, develops rapidly andnew network protocols and technologies are emerging all the time.

8 If youhave built a framework which you then can use to analyse and understandthese new developments, this will ultimately be of more use than a detailedunderstanding of current further objective is to help you be able to make informed choices amongstthe many competing technologies that are available in the marketplace, if ina subsequent career you are required to make such CIS222 module replaces the CIS208 module entitledTelecommunications and Computer communications . Some of thematerial in the CIS208 module has become very dated, as new technologieshave emerged and data transmission speeds have increased way beyondwhat was imagined possible ten years ago.

9 Certain promising technologieswhich were considered important in the CIS208 module have also failed tocome into widespread use, mainly as a result of the phenomenal success ofthe Internet which did not have a very high profile in CIS208. As a result ofthis, the new CIS222 module unlike CIS208 is very much focused on theInternet and its Learning outcomesOn completion of this course and the relevant reading, you should be able to: explain the operation of different data communications protocols andtheir roles within layered network architectures explain the need for standards and outline the roles of the variousstandards bodies responsible for data communications standardisation describe the advantages and disadvantages of different networktopologies and technologies demonstrate skills in using simple network management tools such asping, traceroute and netstat and in using spreadsheets to analyse anddisplay Course outlineThe CIS222 module consists of two distinct parts which correspond to thetwo volumes of the subject guide.

10 The first part of the course is called DataCommunications and is an introduction to the terms, concepts and networkarchitectures required to understand how data is transmitted throughcommunications channels and networks. This, of necessity, requires atechnical approach and some knowledge of the physics of transmission aswell as the study of network architectures and protocols. The second part ofthe module is called enterprise networking and is more concerned with thedesign and management of networks used by businesses and other largeorganisations. It therefore concentrates more on the business andmanagement issues that Volume of the subject guide can be regarded as a comparativetechnical study of layered network protocols1.