Troubleshooting Macintosh Networks Kurt VanderSluis The Network Group, Inc. Table of Contents Introduction..................................................................................................... 1 A World of Abstraction........................................................................................................................1 Using your Pre-Computer Expertise to Overcome the Difficulty.................................................1 Read and Learn Both Practice and Theory......................................................................................2 Troubleshooting Requires a Willingness To Be Both Impulsive and Methodical.....................3 Overcoming the Difficulty—Using this Book...................................................................................3 Two Ways to Read the Book..............................................................................................................4 What If This Book Doesn’t Have the Specific Example I Need?................................................4 The Layout of the Chapters.............................................................................................................5 Troubleshooting Preview.............................................................................. 6 Troubleshooting Requirement 1: The Normal Network................................................................6 Troubleshooting Requirement 2: Tools.............................................................................................7 Troubleshooting Requirement 3: Understanding..........................................................................7 Troubleshooting Algorithms..............................................................................................................8 Random Troubleshooting................................................................................................................8 Hunch-based Troubleshooting.......................................................................................................8 Setup-Oriented Troubleshooting....................................................................................................9 Layer-Oriented Troubleshooting.................................................................................................10 Process-Oriented Troubleshooting..............................................................................................11 Choosing the Best Troubleshooting Mode..................................................................................12 Summary..............................................................................................................................................13 Network Concepts for Troubleshooters...................................................14 Layered Protocols...............................................................................................................................15 Functions of the Layers.................................................................................................................16 Network Addressing...........................................................................................................................17 Group and Individual Addressing................................................................................................17 Hardware and Protocol Addresses................................................................................................18 AppleTalk Addresses and Ethernet Addresses...........................................................................19 Address Numbering Systems........................................................................................................19 Address Fields..................................................................................................................................20 Broadcast and Multicast Addresses..............................................................................................20 AppleTalk Addressing........................................................................................................................21 Network Address.............................................................................................................................21 Extended Networks..........................................................................................................................22 Network Numbers...........................................................................................................................23 Node Address....................................................................................................................................23 Node Address Numbers...................................................................................................................24 Duplicate Node Addresses..............................................................................................................24 Node Addresses in Extended Networks........................................................................................24 Socket Addresses.............................................................................................................................25 Socket Numbers...............................................................................................................................25 Network Relationships......................................................................................................................25 Control of the Relationship—Client-Server and Peer-to-Peer...............................................25 Configuration of Computing Elements.......................................................................................26 Flow Limitations—Finding the Bottleneck..................................................................................28 i TROUBLESHOOTING MACINTOSH NETWORKS Speed Factors...................................................................................................................................28 Effect of Errors................................................................................................................................29 Loss of Connection..........................................................................................................................29 An Example of a Client-Server Relationship.................................................................................30 An Example of a Peer-to-Peer Relationship..................................................................................31 Signaling and Transmission.............................................................................................................31 Network Transmission Theory.........................................................................................................32 Signals Decay over Distance.........................................................................................................32 Loss of Power...................................................................................................................................32 Frequency Distortion.....................................................................................................................32 Reflections.......................................................................................................................................33 Electrical Noise................................................................................................................................33 Network Bandwidth and Utilization................................................................................................34 Calculating Bandwidth...................................................................................................................35 The Effect of Packet Size................................................................................................................36 LocalTalk Bandwidth-Calculation # 1.........................................................................................37 LocalTalk Bandwidth-Calculation # 2.........................................................................................37 Utilization—Using a Stopwatch.....................................................................................................38 Utilization-Calculation #1.............................................................................................................39 Utilization With PacketCrunch....................................................................................................39 Utilization With NetStats................................................................................................................41 Summary..........................................................................................................................................42 Setup Troubleshooting................................................................................43 Troubleshooting LocalTalk Setups: General Information...........................................................44 The Relationship Between Design and Troubleshooting........................................................45 Conceptualizing the LocalTalk Setup..............................................................................................46 The LocalTalk Connector...............................................................................................................46