Introduction to Data Communications
Table of Contents

  1. Introduction 12  
 
  2. Acknowledgements 12  
 
  3. Revision List 13  
 
  4. Data Communications 15  
 
  5. Why Telecommunications? 15  
  a. Voice Channels 15  
  b. Data Channels 16  
 
  6. Introduction to Networking 17  
  a. The Big Picture 17  
  b. Telecommunications Components of The Big Picture 20  
  c. ISO OSI 20  
 
  7. Breaking The Big Picture up! 22  
  a. The Local Loop 22  
  b. LANs 23  
  c. MANs 24  
  d. WANs. 26  
 
  8. Trade Magazines 27  
 
  9. The Role of Telecommunications in Networking 29  
  a. LANs 29  
  b. MANs 29  
  c. WANs 30  
 
  10. Brief History of Networking 31  
 
  11. Data Communication Network 34  
  a. Performance 34  
  b. Consistency 34  
  c. Reliability, 35  
  d. Recovery 36  
  e. Security 36  
  f. Applications 36  
  g. Basic Components 38  
 
  12. Data Flow 40  
 
  13. Modems 43  
  a. Basic Definition 43  
  b. Digital Connection 43  
  c. Analog Connection 45  
  d. External/Internal Modems 45  
  e. Modem Types 47  
  f. Features of Modems 49  
  g. Modem Speeds / Standards 50  
  h. Transfer Rate versus PC Bus Speed 51  
  h. V.90 56 kbps Modems 51  
 
  14. Physical Connection 52  
 
  15. Transmission Media - Guided 53  
  a. Open Wire 53  
  b. Twisted Pair 55  
  c. Coaxial Cable 57  
  d. Optical Fibre 57  
  i. Optical Transmission Modes 59  
  ii. Step Index Mode 61  
  iii. Grade Index Mode 61  
  iv. Single Mode 61  
  v. Comparison of Optical Fibres 63  
  vi. Advantages of Optical Fibre 64  
  vii. Disadvantages of Optical Fibre 65  
  e. Media versus Bandwidth 65  
 
  16. Transmission Media - Unguided 65  
  a. RF Propagation 66  
  i. Ground Wave Propagation 66  
  ii. Ionospheric Propagation 67  
  iii. Line of Sight Propagation 67  
  b. Radio Frequencies 68  
  c. Microwave 69  
  d. Satellite 70  
  e. Iridium Telecom System 72  
 
  17. RS-232D Serial Interface Standard 74  
  a. Mechanical Characteristics of the RS-232D 74  
  b. Electrical Characteristics of the RS-232D 74  
  c. Function of Each Signal 76  
  d. Subsets of Signals for Certain Applications 78  
 
  18. RS-232D Flow Control 80  
  a. Hardware Handshaking 81  
  b. Hardware Null Modems 88  
  c. Software Handshaking (Xon/Xoff) 89  
  d. Software Null Modem 89  
  e. Terminals & PCs 91  
 
  19. Timing 92  
  a. Asynchronous vs. Synchronous Transmission 93  
 
  20. Asynchronous Communications 95  
  a. Start/Stop bits 95  
  b. 7/8 Bit Codes 99  
  c. Parity Bits 101  
 
  21. Line Encoding 104  
  a. Unipolar Encoding 104  
  b. Polar Encoding 106  
  c. Bipolar Line Encoding 108  
  d. Manchester Line Encoding 108  
 
  22. Standard Digital Codes 110  
  a. EBCDIC - Extended Binary Coded Decimal Interchange Code 110  
  b. ASCII - American Standard Code for Information Interchange 116  
 
  23. Voice Channel Communications 121  
  a. Voice Channel Specification 121  
  b. Voice Channel Constraints 122  
  c. Nyquist Theorem 123  
 
  24. Telephone Networks 125  
  a. POTS - Plain Old Telephone Set 125  
  b. Local Loops 129  
  c. Central Office 131  
  d. Hierarchical Phone Networks 131  
 
  25. Telephone Line Characteristics 135  
  a. Attenuation Distortion 135  
  b. Propagation Delay 137  
  c. Envelope Delay Distortion 139  
 
  26. Line Impairments 140  
  a. Crosstalk 140  
  b. Echo or Signal Return 140  
  c. Frequency Shift 142  
  d. Non-Linear Distortion 142  
  e. Jitter: Amplitude and Phase 143  
  f. Transients: Impulse Noise, Gain Hits, Dropouts & Phase Hits 144  
 
  27. Modulation Techniques 147  
  a. AM - Amplitude Modulation 147  
  b. FM - Frequency Modulation 149  
  c. PM - Phase Modulation 149  
 
  28. Modem Modulation 151  
  a. FSK - Frequency Shift Keying 151  
  b. QPSK - Quadrature Phase Shift Keying 155  
  c. QAM - Quadrature Amplitude Modulation 157  
 
  29. AT Command Set 159  
  a. Basic AT commands 160  
 
  30. Multiplexing 161  
  a. FDM - Frequency Division Multiplexing 164  
  b. TDM - Time Division Multiplexing 166  
  c. STDM - Statistical Time Division Multiplexing 168  
 
  31. Telecommunication Multiplexing 168  
  a. FDM - Channel Groups 169  
  b. TDM - T1 Carrier System 169  
 
  32. Introduction to the ISO - OSI Model 172  
  a. OSI Model Explained 172  
  b. Layer 7 - Application Layer 172  
  c. Layer 6 - Presentation Layer 176  
  d. Layer 5 - Session Layer 177  
  e. Layer 4 - Transport Layer 177  
  f. Layer 3 - Network Layer 179  
  g. Layer 2 - Data Link Layer 179  
  h. Layer 1 - Physical Layer 180  
  i. Layer Specific Communication 181  
  j. OSI Model Functional Drawing 183  
 
  33. Synchronous Transmission 185  
  a. Clocking: Self & Manchester Encoding 186  
 
  34. Basic Frame Structure 188  
  a. Preamble: Starting Delimiter/Alert Burst/Start of Header 188  
  b. Address Field(s): Source and/or Destination 188  
  c. Control Field 190  
  d. Data/Message and optional Pad 190  
  e. CRC/ Frame Check Sequence 190  
  f. End Frame Delimiter 190  
 
  35. Physical Layer 192  
  a. Asynchronous & Synchronous Communication 192  
 
  36. IEEE-802.3 Protocol 194  
  a. CSMA/CD (Carrier Sense Multiple Access/ Collision Detect) 194  
  b. IEEE 802.3 Ethernet Media Types 195  
  c. IEEE 802.3 10Base5 196  
  d. IEEE 802.3a 10Base2 200  
  e. IEEE 802.3i 10BaseT 203  
  f. MAC - Medium Access Control 206  
  g. Total Length of a MAC Frame 209  
  h. MAC Frame 211  
  i. Packet Sniffing 212  
  j. Packet Sniffing Block Diagram 216  
 
  37. IEEE 802.2 LLC - Logical Link Control Layer 217  
  a. Service Access Ports (SAPs) 219  
  b. Types of LLC Operation 220  
  c. Classes of LLC 224  
  d. LLC PDU Control Field Formats 224  
 
  38. Network Interface Cards 229  
  a. IRQs, DMAs and Base Addresses 230  
  b. Legacy 234  
  c. NIC Diagnostic Tools 236  
  d. Network Interface Card Drivers 238  
  i. NDIS Drivers 241  
  ii. ODI Drivers 243  
  iii. Packet Drivers 245  
  iv. Software Interrupts 245  
 
  39. Repeaters 247  
  a. Purpose of a Repeater 247  
  b. Repeater's OSI Operating Layer 249  
  c. Repeater's Segment to Segment Characteristics 249  
  d. Repeater Addressing: MAC Layer and Network Segment 251  
 
  40. Hubs 253  
  a. Purpose of Hubs 253  
  b. Hub's OSI Operating Layer 255  
  c. Hub's Segment to Segment Characteristics 255  
  d. Hub's Addressing 257  
  e. Half-Duplex & Full-Duplex Ethernet Hubs 257  
  f. Switching Hubs 258  
 
  41. Bridges 260  
  a. Bridge OSI Operating Layer 260  
  b. Purpose of a Bridge 260  
  c. Bridge Segment to Segment Characteristics 263  
  d. Bridge Methodologies 265  
  e. Reasons to use a Bridge 270  
  f. Bridge Addressing 270  
  g. Collapsed Backbones 270  
 
  42. Routers 272  
  a. Purpose of Routers 272  
  b. Router OSI Operating Layer 272  
  c. Router Segment to Segment Characteristics 274  
  d. Router Addressing 276  
  e. Routing Protocols 276  
  f. RIP - Routing Information Protocol 276  
  g. EGRP - Exterior Gateway Routing Protocol 279  
  h. OSPF - Open Shortest Path First 279  
 
  43. Brouters (Bridge/Routers) 281  
 
  44. Gateway 282  
  a. Gateway's OSI Operating Layer 282  
  b. Gateway Segment to Segment Characteristics 283  
  c. Gateway Addressing 283  
 
  45. Token Ring 284  
  a. IBM Token Ring 285  
  b. IEEE 802.4 Token Bus 286  
  c. IEEE 802.5 Token Ring 286  
  d. IEEE 802.5 Bus Arbitration 286  
  e. 4 / 16 Mbps Transfer Rate 292  
  f. IEEE 802.5 Topology 292  
  g. MSAUs 292  
  i. Token Ring connectors 294  
  ii. MSAU Relay 296  
  iii. Ring In/ Ring Out 296  
  iv. Wrapping 298  
  v. Physical Star/ Logical Ring 299  
  h. IEEE 802.5 and the OSI Model 299  
  i. Token Ring Cabling 302  
  i. Shielded Twisted Pair 302  
  ii. Unshielded Twisted Pair - Type 3 302  
  iii. IBM Cabling System 303  
  j. Ring Insertion 304  
  k. CAUs & LAMs 305  
  l. Ring Calculations 306  
  i. Maximum Ring Length 306  
  ii. Ring Length Calculations 306  
  iii. Mixing Cables and Ring Length 307  
  iii. Active Concentrators and Ring Length 309  
  m. Token Ring Monitors and Servers 311  
  i. Active Monitor (AM) 311  
  ii. Standby Monitor (SM) 316  
  iii. Ring Parameter Server (RPS) 318  
  iv. Configuration Report Server (CRS) 318  
  v. Ring Error Monitor (REM) 320  
  vi. Where are these Monitors? 324  
  n. Token Ring Hierarchy 324  
  o. IEEE 802.5 Frames 326  
 
  46. Linux and Token Ring 336  
 
  47. Source Routing 342  
 
  48. ISDN - Integrated Services Digital Network 344  
 
  49. ADSL - Asymmetrical Digital Subscriber Line 347  
 
  50. Cable Modems 350  
 
  51. Quick Introduction to Unix 352  
  a. Basic Unix Commands 359  
  b. Access and Permissions 362  
  c. Links, Instances & Processes 365  
  d. Background Processing 369  
  e. Shell Programs 371  
  f. Communicating with Other Users 373  
  g. Creating Users and Groups 375  
 
  52. SAMBA, Win95, NT and HP Jetdirect 377  
 
  53. The Suite of TCP/IP Protocols 387  
 
  54. Internet Protocol 389  
  a. IP Addresses 389  
  b. IP Address Classifications 390  
  i. Class A addresses 390  
  ii. Class B addresses 390  
  iii. Class C addresses 391  
  iv. Class D addresses 391  
  v. Class E addresses 391  
  c. Reserved IP Addresses 392  
  d. Network Masking 393  
  e. Domain Names 398  
  f. IP Header 401  
 
  55. Address Resolution Protocol (ARP) 404  
 
  56. Reverse Address Resolution Protocol (RARP) 406  
 
  57. Internet Control Messaging Protocol (ICMP) 407  
 
  58. Transmission Control Protocol (TCP) 416  
 
  59. User Datagram Protocol (UDP) 420  
 
  60. Simple Network Management Protocol 422  
  a. SNMPv2 to the Rescue 423  
  b. MIB - Management Information Base 423  
  c. RMON - Remote Network Monitoring 423  
 
  61. Handy Unix Network Troubleshooting Commands 425  
 
  62. X.25 429  
  a. X.25 OSI Layers 431  
  b. X.25 High overhead 433  
  c. X.25 Packet Formats 435  
 
  63. Frame Relay 439  
  a. Decreased Protocol Overhead 439  
  b. LAPD - Link Access Protocol D channel 441  
  c. LAN to Frame Relay Connection 441  

Appendix

  a. PC Block Diagram 442  
  b. PC Quick ID Guide 445  
  c. Ethernet Type Field 463  
  d. Ethernet Address Assignments 466  
  e. IP Protocol Address Space 470  
  f. IP Multicast Addresses 472  
  g. IP Header Protocols 476  
  h. IP Hardware Types 478  
  i. TCP/IP Well Known Ports 479  
  j. AT Command Set (Partial listing) 493  
  k. ISO 3166 Country Codes 497  
  l. Token Ring - Major Vector IDs 499  
  m. The GNU General Public License 502  
  n. Copyleft Rules & Regulations 508  

 
Introduction to Data Communications
 Previous Top Next