Local Area Networks (LANs):

Transcription

1 Local Area Networks (LANs): Learning Center Student Guide Published by ComputerPREP, Inc. Phoenix, Arizona PCL03-CNLANS-PR-205 Version 6.0P

2 Local Area Networks (LANs) Developers Meagan McLaughlin and Brent Capriotti Editors Jill McKenna and David Oberman Publishers LeAnna Shank and Tina Strong Project Manager Karlene Copeland TRADEMARKS ComputerPREP is a registered trademark of ComputerPREP, Inc. in the United States and other countries. Microsoft, Microsoft Internet Explorer logo, and Windows are either registered trademarks or trademarks of the Microsoft Corporation in the United States and/or other countries. All other product names and services identified throughout this book are trademarks or registered trademarks of their respective companies. They are used throughout this book in editorial fashion only. No such use, or the use of any trade name, is intended to convey endorsement or other affiliation with the book. Copyrights of any screen captures in this book are the property of the software s manufacturer. DISCLAIMER ComputerPREP, Inc. makes a sincere effort to ensure the accuracy of the material described herein; however, ComputerPREP, Inc. makes no warranty, express or implied, with respect to the quality, correctness, reliability, currentness, accuracy, or freedom from error of this document or the products it describes. ComputerPREP, Inc. makes no representation or warranty with respect to the contents hereof and specifically disclaims any implied warranties of fitness for any particular purpose. ComputerPREP, Inc. disclaims all liability for any direct, indirect, incidental, consequential, special, or exemplary damages resulting from the use of the information in this document or from the use of any products described in this document. Mention of any product does not constitute an endorsement by ComputerPREP, Inc. of that product. Data used in examples and sample data files are intended to be fictional. Any resemblance to real persons or companies is entirely coincidental. ComputerPREP, Inc. makes every effort to ensure the accuracy of URLs referenced in all our materials, but we can not guarantee that all will be available throughout the life of the course. When this manual/disk was published, all URLs were checked for accuracy and completeness. However, due to the ever-changing nature of the Internet, some URLs may no longer be available or may have been re-directed. COPYRIGHT NOTICE This Guide is copyrighted and all rights are reserved by ComputerPREP, Inc. No part of this publication may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any language or computer language, in any form or by any means, electronic, mechanical, magnetic, optical, chemical, manual, or otherwise, without the prior written permission of ComputerPREP, Inc., 410 North 44th Street, Suite 600, Phoenix, Arizona Copyright by ComputerPREP, Inc. All Rights Reserved ISBN:

3 iii Table of Contents Course Description...xiii ComputerPREP Courseware...xv Course Objectives...xv Classroom Setup... xvii Lesson 1: Overview Pre-Assessment Questions Introduction Local Area Networks LAN Advantages LAN Elements LAN Users The LAN Market Lesson Summary Lesson 1 Review Lesson 2: Topologies Pre-Assessment Questions Introduction Bus Topologies Ring Topologies Tree Topologies Star Topologies Mesh Topology Wireless (Cell) Topology Hybrid Topologies Lesson Summary Lesson 2 Review Lesson 3: Information Transfer Pre-Assessment Questions Data Transport and Protocols Access Method Overview CSMA/CD (Ethernet) Token Ring Token Bus Summary Lesson Summary Lesson 3 Review Lesson 4: Transmission Techniques Pre-Assessment Questions Analog and Digital Transmissions Baseband Transmission Broadband Transmission Hybrids Fiber Optic Transmission Wireless Transmission Comparison Lesson Summary

4 iv Lesson 4 Review Lesson 5: Transmission Media Pre-Assessment Questions Overview of Transmission Media Twisted Pair Cable Coaxial Cable Fiber Optic Cable Infrared Short-Range Wireless Microwave Satellite Lesson Summary Lesson 5 Review Lesson 6: LAN Standards Pre-Assessment Questions The Elements of a LAN Standard OSI Reference Model TCP/IP SNA IEEE Committees IEEE 802.x Standards Lesson Summary Lesson 6 Review Lesson 7: LAN Components Pre-Assessment Questions Networking Components Servers Network Operating System (NOS) Local Networking Components Internetworking Components Lesson Summary Lesson 7 Review Lesson 8: Network Management Pre-Assessment Questions Network Trends Network Management User Management Network Hardware and Software Management Functional Areas of Network Management Management Protocols Planning a Network Lesson Summary Lesson 8 Review Lesson 9: Advanced LAN Technologies Pre-Assessment Questions From LANs to WAN Basic WAN Technologies Advanced WAN Technologies Frame Relay SONET

5 v Cell Relay: ATM/SMDS/BISDN Virtual Private Networks(VPNs) Lesson Summary Lesson 9 Review Glossary...Glossary-1 Index... Index-1 List of Figures Figure 1-1: Local Area Networks Figure 1-2: Dumb Terminal and Mainframe Link Figure 1-3: Local Area Networks (LANs) Figure 1-4: Wide Area Networks (WANs) Figure 1-5: Mainframe Architecture Figure 1-6: Modems in Mainframe Networks Figure 1-7: LAN Shared Resources Figure 1-8: Shared Databases Figure 1-9: LAN Figure 1-10: File Sharing Figure 1-11: LAN Elements Figure 1-12: Fiber Optic and Wireless LAN Technology Figure 1-13: LAN-to-LAN Connection Figure 1-14: Networking LAN Locations Figure 1-15: LAN Architecture Figure 1-16: LAN Connectivity Figure 2-1: LAN Topologies Figure 2-2: Bus Topology Figure 2-3: Ethernet LAN Figure 2-4: Advantages of Bus Topology Figure 2-5: Disadvantages of Bus Topology Figure 2-6: Token Ring and FDDI Ring Topologies Figure 2-7: Token Ring Topology Figure 2-8: Advantages of Ring Topology Figure 2-9: Disadvantages of Ring Topology Figure 2-10: Tree Topology Figure 2-11: Advantage of Tree Topology Figure 2-12: Disadvantages of Tree Topology Figure 2-13: Star Topology Figure 2-14: Advantages of Star Topology Figure 2-15: Linked Hubs in Star Topologies Figure 2-16: Disadvantages of Star Topology Figure 2-17: Mesh Topology Figure 2-18: Advantage of Mesh Topology Figure 2-19: Disadvantages of Mesh Topology Figure 2-20: Wireless Topology Figure 2-21: Wireless Topology Access Point Figure 2-22: Advantages of Wireless Topology Figure 2-23: Disadvantages of Wireless Topology Figure 2-24: Hybrid Topology Figure 3-1: Packets and Frames Figure 3-2: Packet Structure

6 vi Figure 3-3: HDLC Frame Structure Figure 3-4: Hybrid Network Figure 3-5: OSI Reference Model Figure 3-6: Frame Using OSI Reference Model Figure 3-7: OSI Layer Sending End Layer Functions Figure 3-8: OSI Layer 2 Function Figure 3-9: OSI Receiving End Layer Functions Figure 3-10: LAN Access Methods Figure 3-11: Ethernet Figure 3-12: Token Ring Figure 3-13: CSMA/CD (Ethernet) Figure 3-14: Ethernet Collision Detection Figure 3-15: CSMA/CD Contention Access Method Figure 3-16: Reduced Throughput With Ethernet Figure 3-17: CSMA/CA Figure 3-18: Wireless Networks Use Collision Avoidance Figure 3-19: Physical Star Configuration With Hub Figure 3-20: Physical Star With Logical Bus Configuration Figure 3-21: Intelligent Hub Figure 3-22: Switching Hub Figure 3-23: Virtual LAN Figure 3-24: Switches Supporting Multiple Bandwidths Figure 3-25: Token Ring With Four Stations Figure 3-26: Token Ring With Active Monitor Figure 3-27: Token Ring With Busy Token Figure 3-28: Token With User Data Becomes A Frame Figure 3-29: Destination Station Receives Token Figure 3-30: Destination Station Sets Copy Bit On The Token Figure 3-31: Sending Station Sets Token to Free Figure 3-32: Active and Passive Station Access Figure 3-33: Token Ring Performance Does Not Degrade Figure 3-34: Media Access Unit (MAU) Figure 3-35: Switching MAU Figure 3-36: Token Bus Figure 3-37: High-Priority Bus Stations Assigned Multiple Addresses Figure 4-1: Signals in the Network Figure 4-2: Analog Signal Figure 4-3: Digital Signal Figure 4-4: Broadband Signal Figure 4-5: Baseband Signal Figure 4-6: Analog Signals are Easily Digitized Figure 4-7: CSMA and Token Passing Baseband Transmission Figure 4-8: Advantages of Baseband Transmission Figure 4-9: Disadvantages of Baseband Transmission Figure 4-10: Broadband LAN Tree Configuration Figure 4-11: Broadband Provides Separate Channels Figure 4-12: Head-End Controls Broadband Channels Figure 4-13: Head-End in Tree Configuration Figure 4-14: Broadband Signal Divided into 6-MHz Slices Figure 4-15: Dual Cable Layout in Broadband Figure 4-16: Advantages of Broadband Transmission Figure 4-17: Disadvantages of Broadband Transmission Figure 4-18: Hybrid Systems

7 vii Figure 4-19: Fiber Optic Transmission Figure 4-20: Fiber Divided into Channels Figure 4-21: SONET Bit Rates Figure 4-22: Wireless Transmission Figure 5-1: Network Using Satellite Figure 5-2: Factors Influencing Network Design Figure 5-3: Types of Cable Figure 5-4: Satellite Transmission Figure 5-5: Star Configuration Using Twisted Pair Figure 5-6: Twisted Pair Cable Figure 5-7: Twisted Pair Cable Affected by Crosstalk Figure 5-8: Benefits of Tight and Loose Twisted Pair Cable Figure 5-9: Electromagnetic Interference (EMI) Figure 5-10: Radio Frequency Interference (RFI) Figure 5-11: Shielded Twisted Pair Cable Figure 5-12: Unshielded Twisted Pair (UTP) Figure 5-13: American Wire Gauge Standard Figure 5-14: Relationship Between Gauge and Attenuation Figure 5-15: Networks Using Voice Grade and Data Grade Figure 5-16: Using UTP Cable Figure 5-17: Using STP Cable Figure 5-18: Networks Using Coaxial Cable Figure 5-19: Coaxial Cable Figure 5-20: Coaxial Cable Carries Digital Signals Figure 5-21: Coaxial Cable Uses Radio Grade Cable Standard Figure 5-22: Thin Coaxial Cable Figure 5-23: Thick Coaxial Cable Figure 5-24: Coaxial Cable Transmission Limits Figure 5-25: Fiber Optic Ring Figure 5-26: Fiber Optic Cable Figure 5-27: Single Mode and Multimode Fibers Figure 5-28: Smearing in Fiber Optic Cable Figure 5-29: Comparison of Single Mode and Multimode Fiber Figure 5-30: Fiber Optic Light Source and Receiver Figure 5-31: Fiber Optic Cable Uses Light Pulses Figure 5-32: Frequency of LED and Laser Light Sources Figure 5-33: Comparison of LED and Laser Light Sources Figure 5-34: SLM Versus MLM Lasers Figure 5-35: Infrared Laptop Figure 5-36: Network With Infrared Devices Figure 5-37: Short-Range Wireless Network Figure 5-38: Transmission Rates of Short-Range Wireless Networks Figure 5-39: FHSS and DSSS Encoding Methods Figure 5-40: Microwave Network Figure 5-41: Distance Limits of Microwave Transmissions Figure 5-42: LECs and IXCs Use Microwave Transmission Figure 5-43: Microwave Transmission Between Buildings Figure 5-44: Disadvantages of Microwave Networks Figure 5-45: Satellite Does Not Require Line of Sight Figure 5-46: Components of a Satellite Network Figure 5-47: Orbits of GEOs, MEOs, and LEOs Figure 5-48: Transponders in a Satellite Figure 5-49: The Transmission Process in a Satellite Network

8 viii Figure 6-1: Local Area Network (LAN) Figure 6-2: Hybrid LAN Figure 6-3: Bus and Ring LAN Configurations Figure 6-4: IEEE Committees Figure 6-5: Digital Signal Figure 6-6: Frame Structure Figure 6-7: OSI Reference Model Figure 6-8: 802.x Standards Contained in OSI Layers 1 and Figure 6-9: OSI Model Sending Process Figure 6-10: OSI Model Receiving Process Figure 6-11: OSI Reference Model Transmission Process Figure 6-12: Complex LAN Network Figure 6-13: Comparison of OSI Model and TCP/IP Figure 6-14: TCP/IP Network Access Layer Figure 6-15: TCP/IP Internet Layer Figure 6-16: TCP/IP Host-to-Host Layer Figure 6-17: TCP/IP Process Layer Figure 6-18: Comparison of SNA and the OSI Model Figure 6-19: SNA Logical Services Figure 6-20: Physical Services Figure 6-21: Complex LAN Network Figure 6-22: IEEE 802.x Committees Develop Standards for OSI Layers 1 and Figure 6-23: Complex LAN Network Figure 6-24: OSI Data Link Layer Relates to the LLC and MAC Protocols Figure 6-25: IEEE Incorporated in OSI Layer Figure 6-26: Complex LAN Network Figure 6-27: 10BaseT Supports 10 Mbps Over Twisted Pair Figure 6-28: 10BaseT and 100BaseT are Compatible Figure 6-29: IEEE Rates Will Increase to 1Gbs Figure 6-30: IEEE Token Bus Standard Figure 6-31: IEEE Token Ring Standard Figure 6-32: IEEE Distributed Queue Dual Bus Figure 6-33: IEEE Broadband Transmission Standard Figure 6-34: IEEE Fiber Distributed Data Interface (FDDI) Figure 6-35: Copper Distributed Data Interface (CDDI) Figure 6-36: IEEE Integrated Services Figure 6-37: IEEE LAN Security Figure 6-38: IEEE Wireless LANs Figure 6-39: IEEE b Supports Ad Hoc and Infrastructure Models Figure 6-40: IEEE VG-AnyLAN Figure 6-41: 100VG Parent and Child Hubs Figure 6-42: 100VG Has Unique MAC Layer Figure 6-43: IEEE Cable TV Broadband Services Figure 6-44: IEEE Wireless Personal Area Network (WPAN) Figure 6-45: IEEE Broadband Wireless Networking Figure 7-1: Complex LAN Network Figure 7-2: Server Figure 7-3: Physical Ring With Multiple Servers Figure 7-4: Peer-to-Peer Network Figure 7-5: Networks Use a Variety of Media Figure 7-6: Network Interface Card Figure 7-7: Server Figure 7-8: Disk Server

9 ix Figure 7-9: File Server Figure 7-10: File Servers Provide Centralized Storage and Security Figure 7-11: Database Server Figure 7-12: Database Servers Use Shared Locks or Exclusive Locks Figure 7-13: Structured Query Language (SQL) Figure 7-14: Print Server Figure 7-15: Printer Acting as a Print Server Figure 7-16: Application Server Figure 7-17: Communication Server Figure 7-18: Communication Server Connected to the Internet Figure 7-19: Internet Server Figure 7-20: Gateway Server Figure 7-21: Network Operating System (NOS) Figure 7-21: NOSs Provide Resource Sharing and User Logon Controls Figure 7-22: Redundant Array of Inexpensive Disks (RAID) Figure 7-23: Disk Mirroring Figure 7-24: Disk Duplexing Figure 7-25: RAID 5 Uses Multiple Hard Disks Figure 7-26: Disk Caching Figure 7-27: Elevator Seeking Figure 7-28: Physical Ring With Multiple Servers Figure 7-29: Network Adaptor Figure 7-30: Physical Ring With Multiple Servers Figure 7-31: LANs connected With Repeaters Figure 7-31: Repeater Regenerates Signals to Extend Signal Range Figure 7-32: Multiport Repeater (MPR) Figure 7-33: Complex Network With Bridge, Router, and Gateway Figure 7-34: Bridge, Router, and Gateway Figure 7-35: Physical Rings Connected With a Bridge Figure 7-36: Bridges Operate at the MAC Sublayer of the OSI Data Link Layer Figure 7-37: Bridges Segregate Traffic Between Two Network Segments Figure 7-38: Multiport Bridges Connect LANs With Different Architecture and Cabling Figure 7-39: Physical Rings Connected With Routers Figure 7-40: Routers Operate at the Network Layer of the OSI Model Figure 7-41: Routers Must Know Each Network s Addresses to Route Packets Figure 7-42: Gateway Figure 7-43: Gateways Operate at the Transport Layer of the OSI Model Figure 7-44: Brouters Combine the Functionality of Bridges and Routers Figure 8-1: Complex Local Area Network Figure 8-2: Simple Local Area Network Figure 8-3: Heterogeneous Local Area Network Figure 8-4: LANs Can be Connected Across the Country Figure 8-5: LAN Users Have Different Needs Figure 8-6: LANs Interconnected With Satellite Figure 8-7: Physical Ring With Multiple Servers Figure 8-8: Network Management Figure 8-9: Software Distribution in a Physical Ring Figure 8-10: Software Distribution is Complex in Enterprise LANs Figure 8-11: Software Distribution Using a Distribution Server Figure 8-12: File Location Management Using File Servers Figure 8-13: Workstation Configuration Includes Several Facets Figure 8-14: Individual Configuration Settings Available from Any Workstation Figure 8-15: Capacity for Extension is a Critical Network Issue

10 x Figure 8-16: Monitor Network Usage to Avoid Overload Figure 8-17: Management Traffic Can Contribute to Network Overload Figure 8-18: Flexibility Allows a Network to Respond to the Unexpected Figure 8-19: Firewalls Offer Protection for Network Internet Connections Figure 8-20: There are Several Network Management Methods Figure 8-21: Distributed Network Management Figure 8-22: Protocol Standards Ensure Compatibility Figure 8-23: Test Points Facilitate Monitoring and Maintenance Figure 8-24: Additional Network Management Issues Exist for WANs Figure 8-25: User Management is Important to Network Management Figure 8-26: User Management Involves Names, Passwords, and Access Rights Figure 8-27: Responding to User Questions Can be Time-Consuming Figure 8-28: Network Hardware and Software Management Involves Several Tools Figure 8-29: More Complex Networks Require Higher-Level Management Tools Figure 8-30: Physical Layer Tools Figure 8-31: Time-Domain Reflectometer (TDR) Figure 8-32: TDRs Locate Media Problems, Faulty Connections, Cut Cables Figure 8-33: TDRs and OTDRs Can Drastically Reduce Time Required for Diagnosis Figure 8-34: Network Monitoring Tools Figure 8-35: Traffic Overload Alarms are Examples of Network Monitoring Tools Figure 8-36: Network Analysis Tools Provide Extensive Quantitative Data Figure 8-37: Data About Printer Use Can Determine the Need for Additional Printers Figure 8-38: Network Analysis Can Identify Traffic from Unknown Sources Figure 8-39: Workstations Send System Information to the Network Analyzer Figure 8-40: Integrated Network Management Figure 8-41: SNMP, DMI, and CMIP are the Three Major Protocol Families Figure 8-43: Network Analysis Uses ISO Functional Areas 1 and Figure 8-44: Five ISO Network Management Functional Areas Figure 8-45: Configuration Management Figure 8-46: Configuration Management Involves Network Hardware and Software Figure 8-47: Fault Management Figure 8-48: Collision Tracking is Part of Fault Management Figure 8-49: Fault Management Can Require Hypothesis Testing Figure 8-50: Advanced Fault Detection Can Reduce the Need for Hypothesis Testing Figure 8-51: Performance Management Figure 8-52: Baselining Provides Overview of Typical Performance Figure 8-53: Comparison of Baseline and Current Performance Reveals Fault Source Figure 8-54: Polling Nodes is an Example of Real-Time Performance Management Figure 8-55: Accounting Management Figure 8-56: Accounting Information Used to Bill Departments for Network Time Figure 8-57: Security Management Figure 8-58: Servers Can be Protected by Restricting Access Figure 8-59: Unauthorized Tapping Can be Done Physically or Remotely Figure 8-60: Different Users Have Different Access Figure 8-61: Encryption Can Protect Data From Users Without the Key Figure 8-62: Data Systems Perform Management Functions at Specified Intervals Figure 8-63: SNMP, DMI, and CMIP Define How Data is Transferred Figure 8-64: Protocols Work With MIB and SMI Figure 8-65: Network Elements Defined and Monitored by Management Stations Figure 8-66: Protocol is Used to Move Information Across the Network Figure 8-67: Simple Network Management Protocol (SNMP) Figure 8-68: SNMP Requests One Record at a Time Figure 8-69: Desktop Management Interface (DMI)

11 xi Figure 8-70: DMI Consists of the Service Layer, CI, MIF, and MI Figure 8-71: DMI Handles All Tasks Using the Same Process Figure 8-72: Common Management Information Protocol (CMIP) Figure 8-73: Network Managers Have a Choice of Management Protocols Figure 8-74: Networks May Use More Than One Management Protocol Figure 8-75: Heterogeneous Interconnected Network Figure 8-76: Determining the Needs of the Users is the First Step in Network Planning Figure 8-77: Look at the Needs of Each Workgroup, Then Tie Them Together Figure 8-78: Focus on Common Elements in Networks Figure 8-79: There are Many Advantages to Interconnection Figure 9-1: Wide Area Network (WAN) Figure 9-2: Small Local Area Network (LAN) Figure 9-3: Metropolitan Area Network (MAN) Figure 9-4: Wide Area Network (WAN) Using Satellite Figure 9-5: WANs Use Many Different Connection Methods Figure 9-6: WAN Connected Over the PSTN Using Modems Figure 9-7: WAN Connected Using Leased T1 Circuits Figure 9-8: International WAN Using T1 Links Figure 9-9: T1 Uses Twisted Pair, T3 Uses Twisted Pair or Fiber Optic Figure 9-10: T1 Connection Using a Single Channel Figure 9-11: T1 Using Separate Channels for Voice, Video, and Data Figure 9-12: Comparison of Bandwidth Required for FT1, T1, and T Figure 9-13: Statistical Multiplexing Provides Bandwidth Based On Demand Figure 9-14: Statistical Multiplexing Conserves Bandwidth Figure 9-15: FT1 Requires Two T1 DS0 Channels, One for Voice and One for Data Figure 9-16: Voice Line Is In Use During the Day, While the Data Line Is Used at Night.9-11 Figure 9-17: Voice and Data Use the Same Channel, Based on Demand Figure 9-18: Packet-Switching Network Figure 9-19: Packets are Routed Based on Address Information Figure 9-20: X.25 Can Accommodate Various Packet Protocols Figure 9-21: An X.25 Gateway Connects a LAN to the Public Network Figure 9-22: Integrated Services Digital Network (ISDN) Figure 9-23: ISDN can be Implemented as PRI or BRI Figure 9-24: ISDN Uses a Single Phone Line for Voice, Data, Video, and Fax Figure 9-25: ISDN Connects Telecommuters to Their Office LANs Figure 9-26: Advanced WAN Technologies Figure 9-27: Frame Relay, Cell Relay, and SONET are OSI-Compliant Figure 9-28: Frame Relay Frames are Forwarded from Network to Network in Hops Figure 9-29: Error Checking in Frame Relay is Performed at the Destination Node Figure 9-30: One Switched Frame Relay Circuit Will Replace Many Dedicated Circuits Figure 9-31: Frame Relay is Not Optimized for Delay-Sensitive Traffic Figure 9-32: Synchronous Optical Network (SONET) Figure 9-33: SONET Backbones Used for SMDS, BISDN, and Voice, Video, and Data Figure 9-34: SONET ADMs Insert and Extract Payloads Without Multiplexing Figure 9-35: Synchronous Payload Envelope (SPE) Surrounded by STS Frame Figure 9-36: Comparison of STS and the Digital Hierarchy Figure 9-37: Advantages of SONET Figure 9-38: SONET Backbone Supports ATM, SMDS, and BISDN Applications Figure 9-39: SONET Ring With ADMs Surrounding Metropolitan Area Figure 9-40: SONET Can Reroute Traffic In the Opposite Direction If the Ring is Cut Figure 9-41: Cell Relay Technologies Figure 9-42: Cell Relay Uses Fixed Frame Size to Control Delay Figure 9-43: SMDS, BISDN, and ATM are OSI-Compliant

12 xii Figure 9-44: Asynchronous Transfer Mode (ATM) Figure 9-45: ATM Serves the Data Link Layer of the OSI Reference Model Figure 9-46: Video and Voice Require Constant Data Rate Figure 9-47: ATM Provides Switching, and SONET Provides Physical Transport Figure 9-48: ATM Handles Information at Faster Rates Than Other Technologies Figure 9-49: ATM Can Handle Any Mix of Data, Video, and Voice Traffic Figure 9-50: Switched Multimegabit Data Service (SMDS) Figure 9-51: SMDS Uses 53-Octet Cells Figure 9-52: SMDS is a Connectionless Protocol Figure 9-53: SMDS Switches Can be Used to Create Enterprise Networks Figure 9-54: Broadband Integrated Services Digital Network (BISDN) Figure 9-55: BISDN Addresses the Network Layer of the OSI Reference Model Figure 9-56: BISDN is Designed for Business and Residential Use Figure 9-57: BISDN Transports Information From Different Applications as Cells Figure 9-58: BISDN Can be Used to Integrate Cell Relay With SONET Transport Figure 9-59: BISDN Can Support Dial-Up Access and VPNs Figure 9-60: Virtual Private Networks (VPNs) Figure 9-61: VPN Tunnel

13 xiii Course Description Welcome to Local Area Networks (LANs). This course will help you prepare for the Certified in Convergent Network Technologies (CCNT) exam, a program sponsored by the TIA (Telecommunications Industry Association). This course is aimed at preparation and review for the Local Area Networks (LANs) module of the CCNT exam, as well as professional development for IT professionals. It is designed to be used in a lecture-based classroom setting. Local Area Networks explains the concepts and technology of LAN topologies, information transfer, transmission techniques, media standards, network management, and the future of LAN. This course has nine lessons, and each lesson covers several topics. Following are the nine lessons to the LANs course, along with the topics covered in each lesson.

14 xiv Topics Covered Overview Introduction Local Area Networks LAN Advantages LAN Elements LAN Users The LAN Market Topologies Introduction Bus Topologies Ring Topologies Tree Topologies Star Topologies Mesh Topology Wireless (Cell) Topology Hybrid Topologies Information Transfer Data Transport and Protocols Access Method Overview CSMA/CD (Ethernet) Token Ring Token Bus Summary Transmission Techniques Analog and Digital Transmissions Baseband Transmission Broadband Transmission Hybrids Fiber Optic Transmission Wireless Transmission Comparison Transmission Media Overview Twisted Pair Cable Coaxial Cable Fiber Optic Cable Infrared Short-Range Wireless Microwave Satellite LAN Standards The Elements of a LAN Standard OSI Reference Model TCP/IP SNA IEEE Committees IEEE 802.x Standards LAN Components Networking Components Servers NOS Local Networking Components Internetworking Components Network Management Network Trends Network Management User Management Network Hardware and Software Management Functional Areas of Network Management Management Protocols Planning a Network Advanced LAN Technologies From LANs to WAN Basic WAN Technologies Advanced WAN Technologies Frame Relay SONET Cell Relay: ATM/SMDS/BISDN Virtual Private Networks (VPNs)

15 xv ComputerPREP Courseware This learning guide was developed for instructor-led training and will assist you during class. Along with comprehensive instructional text and objectives checklists, this learning guide also includes pre-assessment questions, tech terms, and lesson summaries and reviews. Each lesson in this course follows a regular structure, along with graphical cues to illustrate important terms and concepts. The structure of a typical module includes: Pre-Assessment Questions Each lesson includes pre-assessment questions to test student s understanding of the key concepts presented in the lesson. Objectives Each lesson includes a list of objectives to set the stage for the rest of the lesson. Tech Terms All terms that are defined throughout the text appear in bold font. Lesson Summary The Lesson Summaries at the end of each lesson includes: an Application Project to extend learning, a Skills Review of key concepts and objectives presented in the lesson, and Lesson Review Questions designed to test understanding. Glossary The Glossary contains a list of key terms defined throughout the course, and can be used for self-study once the course has been completed. Table of Contents and Index The Table of Contents appears at the beginning of the book, and the Index appears at the end. These can also be used to review key areas. Course Objectives Describe network use before present-day LANs. Describe a present-day LAN. Identify the primary advantages provided by a LAN. Identify the basic elements of a LAN. Identify common user groups of LAN technology. Identify the primary issues confronting the LAN market. Identify the four LAN topologies. Describe the features and functions of bus topologies. Describe the features and functions of ring topologies. Describe the features and functions of tree topologies. Describe the features and functions of star topologies.

16 xvi Identify type of hubs and their features and functions. Describe basic data transport in a LAN. Describe the primary access methods for LANs. Describe the features and functions of CSMA/CD (ethernet) access method. Describe the features and functions of the token ring access method. Describe the features and functions of the token bus access method. Discuss the factors involved in choosing an access method. Describe the different types of signals that require transmission. Describe baseband transmission within a LAN. Describe broadband transmission within a LAN. Describe hybrid transmission techniques. Describe fiber optic transmission within a LAN. Describe wireless transmission techniques and their relationship to LAN technologies. Differentiate between the transmission techniques. Identify key considerations in selecting transmission media in networks. Identify the features, functions, and uses of twisted pair cable. Identify the features, functions, and uses of coaxial cable. Identify the features, functions, and uses of optical fiber cable. Identify the features functions, and uses of infrared transmission. Identify the features, functions and uses of short-range wireless transmission. Identify the features, functions, and uses of microwave transmission. Identify the features, functions, and uses of satellite transmission. Describe the current state of LAN standards. Describe the structure and function of the OSI reference model. Describe the TCP/IP network protocols. Describe the SNA network protocols. Describe the purpose of the IEEE committees.

17 xvii Identify IEEE 802.x standards. Describe components used in a network. Describe different types of network servers. Describe the features and functions of a network operating system (NOS). Describe the networking components used in a local LAN. Describe the internetworking components used in networking. Discuss network management trends. Discuss common network management issues. Discuss the issues involving network user management. Discuss tools available for network hardware and software management. Discuss the ISO network management functional areas. Discuss the role of network management protocols. Describe the issues surrounding network planning. Discuss the issues behind the development of new LAN technologies. Describe the basic WAN technologies. Describe advanced data transmission technologies. Describe frame relay technology. Describe SONET technology. Describe cell relay technology. Describe the significance of virtual private networks (VPNs) over the Internet to WANs. Classroom Setup Student computers are not required for this seminar course. If the instructor wants to deliver supplemental activities or quizzes electronically, computers that meet the instructor's needs will be required for each student. Otherwise, all supplemental material can be distributed as hard-copy documents and completed by students using a pen and paper.

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19 1Lesson 1: Overview OBJECTIVES By the end of this lesson, you will be able to: Describe network use before present-day LANs. Describe a present-day LAN. Compare and contrast basic LAN and WAN features. Identify the key components of a LAN. Identify the primary advantages provided by a LAN. Identify the basic elements of a LAN. Identify common LAN technologies. Identify current issues confronting the LAN market.

20 1-2 Local Area Networks (LANs) Pre-Assessment Questions 1. Unlike mainframe networks, LANs use computing resources. a. Single b. Common c. Distributed d. Personal 2. True or false: An access method defines the way information is transported through the network. 3. Is the LAN market limited to corporate and other large environments, or more broad-based?

21 Lesson 1: Overview 1-3 Introduction This course is about the basics of local area networks, or LANs. You will learn how LANs differ from their mainframe predecessors and what elements make up LANs today. local Figure 1-1: Local Area Networks area network (LAN) A network providing data communication between computer stations, usually limited to a single building or complex of buildings. As recently as 15 years ago, when a user worked on a network, it was most likely at a dumb terminal linked to a mainframe. LANs were still in their infancy and were being designed to match the mainframe environment as closely as possible.

22 1-4 Local Area Networks (LANs) dumb mainframe Figure 1-2: Dumb Terminal and Mainframe Link terminal A computer terminal with limited capacity to manage either its own functions or the communication channel to the host computer. A large, powerful central computer that performs the processing for a network of remote terminals. Today, the "terminal" is almost exclusively a personal computer (PC) linked to a LAN. Dumb terminals are rarely seen, and when required, are emulated through applications running on a PC. personal computer (PC) A desktop computer system. Local Area Networks A LAN is a data communication network that pulls together computing resources such as PCs, printers, miniframes, and mainframes. These elements are linked by a transmission cable or other transmission media. It is common to find LANs consisting entirely of PCs, with some serving in roles traditionally restricted to minicomputers (sometimes called "miniframes") and mainframes. Modern networks often include modems and other remote communication devices to support Internet access, remote user access, and remote LAN connectivity.

23 Lesson 1: Overview 1-5 modem MOdulator/DEModulator. Device that converts digital signals to analog signals for transmission on analog telephone lines. Figure 1-3: Local Area Networks (LANs) A defining quality of a LAN is its size. A LAN typically spans a limited geographic area, usually no more than a building or campus. For larger areas, metropolitan area networks (MANs) or wide area networks (WANs) are needed. MANs and WANs are connected with bridges and routers and generally use the public telephone network for transmission. The term MAN is not commonly seen, with the term WAN assumed to include the MAN designation. Figure 1-4: Wide Area Networks (WANs)

24 1-6 Local Area Networks (LANs) metropolitan wide area network (MAN) A network with a physical extent of several miles for example, a city and its suburbs. MANs are usually made of individual LANs linked with specialized hardware and telephone lines. area network (WAN) A network with unlimited physical extent, such as cities on both coasts of the United States. Usually made of linked LANs or terminal-to-host networks. The predecessors to the LAN were the early mainframe networks. Mainframe architecture is characterized by several terminals cabled to a single mainframe. Without the mainframe, the individual terminal is worthless, because it has no memory or processor of its own. Figure 1-5: Mainframe Architecture Cable connections were limited in length because cables reach only so far. Modems, however, let mainframe networks expand. Modems convert the computer s digital signals to analog signals, which can be sent over the telephone network, connecting terminals hundreds of miles apart. digital analog signal An electrical signal that varies in discrete steps. signal An electrical signal that varies continuously in amplitude and frequency.

25 Lesson 1: Overview 1-7 Figure 1-6: Modems in Mainframe Networks Although some of these early networks grew very large, the basic architecture was the same: one host computer controlling many individual terminals. The host computer processed all requests; the terminals did not have the ability to process any information, other than to send it to the host computer. The growing popularity of the personal computer allowed improvement in the network area. Unlike a simple terminal, the personal computer provided a processor and considerable memory of its own. With the advent of the personal computer, tasks could now be shared between the client and the server. Departments that previously had to submit requests only to have them queued up for access to a mainframe began to demand personal computer power on the desktop. Other departments wanted personal computer resources also. For many companies, personal computers proved an economical and popular upgrade to existing mainframe networks. Ultimately, the result was LANs that were structured around distributed computing, characterized first by client/server applications and later by other PC-oriented application models, rather than a single central mainframe. In some cases, each department developed its own LAN. Different LANs serve different purposes. It is not unusual to find several independent LANs within a single organization. Businesses link these LANs in increasingly large and complex networks. distributed computing Application model in which application components tasks that must be performed by the application are shared by different computers on the network. LAN Advantages LANs enable the sharing of resources. Commonly shared resources include processing power, storage, printers, modems, and video telephone communications.

26 1-8 Local Area Networks (LANs) Figure 1-7: LAN Shared Resources LANs also enable an organization to integrate functions and provide special services. LAN services can include shared databases, shared communication links, audio and video conferencing, Internet firewalls, and so on. Figure 1-8: Shared Databases LANs also provide efficient communication. The most common example is electronic mail, or . With , all users have a network address. Users can send memos or other messages to one individual or to a group of people. By linking the LAN to the Internet, can be used for easy, inexpensive worldwide communication. Figure 1-9: LAN

27 Lesson 1: Overview 1-9 electronic mail ( ) A messaging system operating over a communications medium. is typically implemented through a specialized server and includes links to the Internet for external communications. Another example of efficient communication is file sharing. Two users can access and make changes to the same file. This is often one of the key reasons for initially implementing a LAN. Modern LANs can even enable offline access to files with automatic synchronization when the user connects to the LAN. file Figure 1-10: File Sharing sharing A feature of network operating systems that allows multiple users access to the same file. LAN Elements The simplest perception of a LAN is a collection of computers and peripherals that are connected. In fact, to many LAN users, that is all they need and care to know. But for even the simplest LAN to work well, many hardware and software elements are involved. Figure 1-11: LAN Elements

28 1-10 Local Area Networks (LANs) peripheral Device on a network that provides input/output (such as printers) or auxiliary functions (such as data storage). The components of a LAN help people do useful work or support the proper function of the network. A station is a terminal, personal computer, or workstation that gives the user access to the network. It is one type of node. node Any device on the network other than the network cabling. Nodes include user stations, network servers, multiuser computers, bridges, routers, and gateways. Some nodes are devices that transmit network data from one point to another or monitor a particular operation. An example might be a dedicated computer that monitors a factory operation and sends a report to another node, such as the operator s station. Other nodes include storage and output devices such as databases and printers. The LAN's architecture refers to the overall structure and major characteristics of the network. These characteristics include: The network's topology how the nodes are connected. The access method how a node puts information onto the network. The transmission technique how information passes through the network. The transmission media (cable or wireless transmission) used. The use of specific protocols (rules) defining communication between computers. The LAN's interconnectivity how it shares information with other networks. topology access protocol A description of the physical layout of a network. method A technique used by a node to place its signal on a network. Common LAN access methods include CSMA/CD, CSMA/CA, and token passing. A formal set of rules. In a LAN context, a protocol refers to the standardized rules governing network functions that strongly influence the design of network components.

29 Lesson 1: Overview 1-11 interconnectivity The ability to physically connect with other networks. Interconnectivity does not take into account whether information from one network can be understood by another. As LAN technology has improved, ideas have changed. Optical fiber to the desktop was once thought to be both impractical and expensive, but many networks have migrated in that direction. Another popular option is wireless LAN technology, which provides an added element of portability. Figure 1-12: Fiber Optic and Wireless LAN Technology Another example of improved technology is the connection of LANs over the public telephone network and other connection technologies. Standard telephone connections are typically considered too slow for most LAN-to-LAN applications, but are commonly used for remote user access. Figure 1-13: LAN-to-LAN Connection

30 1-12 Local Area Networks (LANs) WAN connections are typically implemented through higher-speed, higherbandwidth links that provide better access to network data. One popular option is to use the Internet as a WAN backbone. LAN Users Some of the first distributed processing networks were set up in factories, with nodes monitoring and controlling automated manufacturing equipment and assembly lines. In the scientific community, similar LANs recorded data. Others facilitated communication between research teams in different geographic locations. Figure 1-14: Networking LAN Locations The "grandfather of LANs" was a data communication network called the Advanced Research Projects Agency Network (ARPAnet), now part of what has grown to become the Internet. The ARPAnet was (and the Internet is) a wide area network (WAN), because it connects a series of international computer networks. Any time you connect two LANs together, you have a WAN. From these humble beginnings, LANs have become both a standard and an expectation. Organizations that do not include a LAN as part of the computer support solution have become the exception. Many organizations have become completely dependent on their LANs as a way of doing business, with LAN failures bringing all work to a sudden halt. Once unheard of (and unthinkable), home LANs are a fast growing part of the LAN market. Improvements in LAN technologies, cost reductions in LAN hardware, and the integration of network support into most PC operating systems have helped to drive the growth of home LANs. One major influence on this growth is the desire to share a high-speed Internet connection, such as

31 Lesson 1: Overview 1-13 cable modems or digital subscriber line (DSL) modems, with all of the computers in a home. Satellite television operators have also recently started offering Internet access service. cable digital modem Internet connection device that provide a high-speed shared Internet connection through existing cable television lines. subscriber line (DSL) DSL or xdsl. A set of technologies that provides a low-cost, easily accessible, copper-based solution to the need for T1/E1 service. Some xdsl technologies are based on modems, whereas others are based on the use of a CSU/DSU. The LAN Market Because LANs were developed to respond to specific market needs, a variety of LAN architectures are available, mostly incompatible. Vendors of LAN equipment generally design their hardware and software to fit the specifications of a particular LAN architecture. Figure 1-15: LAN Architecture User and corporate expectations in LAN connectivity have resulted in cooperative ventures among designers, vendors, and organizations that set standards for LAN architectures. Connectivity has become less an issue of which vendors you select than which LAN technologies you choose to

32 1-14 Local Area Networks (LANs) implement. You will learn about common LAN standards and their features in this course. standards Figure 1-16: LAN Connectivity Agreed-upon principles governing the design and implementation of hardware or software, including principles governing networking. Though interoperability is key to the widespread use of LANs and WANs, not all standardization issues have been worked out. Work in the standards area is ongoing. LAN bandwidth continues to increase and costs continue to drop, but at the same time, user expectations continue to climb. interoperability The ability of networks and/or network equipment to operate with one another. Another important issue addressed by new architectures is speed. Like the early computers, early LANs were relatively slow. As users have become familiar with LAN resources, they have demanded more. The newest LAN architectures, whether stand-alone or designed to be connected to high-speed WANs, offer more speed and more sophisticated capabilities.

33 Lesson 1: Overview 1-15 Lesson Summary Application project Discuss the impact that remote access requirements and the growth of home networks might have on LAN standards currently under development. Consider the expectation of many users to be able to connect at any time or anywhere. Skills review Following are the key point presented in this lesson: As recently as 15 years ago, when a user worked on a network, it was most likely at a dumb terminal linked to a mainframe. Today, the "terminal" is almost exclusively a personal computer (PC) linked to a LAN. Dumb terminals are rarely seen, and when required, are emulated through applications running on a PC. A LAN is a data communication network that links PCs, printers, minicomputers, and mainframes with a transmission cable or other transmission media. Modems convert the computer's digital signals to analog signals, which can be sent over the telephone network, connecting terminals hundreds of miles apart. Although early networks grew very large, the basic architecture was the same: one host computer controlling many individual terminals. Ultimately, LANs were structured around distributed computing applications rather than a single central mainframe. LANs enable an organization to share resources and integrate functions. LANs also provide efficient communication. Each node in a LAN is associated with a particular network task. A station is one type of node. It is a terminal, personal computer, or workstation that gives the user access to the network. Other nodes include storage and output devices such as databases and printers. The LAN's architecture refers to the overall structure and major characteristics of the network. These characteristics include the network's topology, the access method, the transmission technique, the transmission media (cabling) used, the use of specific protocols, and the LAN's interconnectivity. Optical fiber to the desktop was once thought to be both impractical and expensive, but many networks have migrated in that direction. Another popular option is wireless LAN technology, which provides an added element of portability.