principles of synchronous digital hierarchy - gbv of synchronous digital hierarchy rajesh kumar jain...
TRANSCRIPT
Principles of
Synchronous
Digital
Hierarchy
RAJESH KUMAR JAIN
Cffij2\ CRC PressTaylor&Francis GroupBoca Raton London NewYork
CRC Press is an imprint of the
Taylor & Francis Croup, an informa business
Contents
Preface xix
Author,
xxiii
1. Introduction~
1
1.1 You and Me . 1
1.2 "Mr, Watson, Come Here. I Want to See You." 1
1.3 Technology of the Telephone.... 2
1.3.1 Transmitter 3
1.3.2 Receiver 4
1.3.3 Metallic Wires 4
1.4 Telephone Exchanges 6
1.4.1 Manual Exchange 6
1.4.2 Automatic Exchanges 7
1.5 Long-Distance Communication 8
1.6 Need for Multiplexing 9
1.7 Techniques of Multiplexing 9
1.8 Multiplexing Structure of FDM Schemes 11
1.9 Capacities of Various Analog (FDM) Multiplexing Systems 13
1.9.1 Copper Wire Pairs 13
1.9.2 Coaxial Cables 13
1.9.3 Microwave Systems 13
1.10 Digital Multiplexing , ,14
1.10-1 Plesiochronous Digital Hierarchy 14
1.10.2 Synchronous Digital Hierarchy 15
1.10.3 Coarse Wavelength Division Multiplexing 15
1.10.4 Dense Wavelength Division Multiplexing 16
1.10.5 Optical Transport Network 16
Review Questions 16
Critical Thinking Questions 17
Bibliography 17
2. Advent of Digital Technology 19
2.1 Analog Communication Systems 19
2.2 Problems in Analog Communication Systems 20
2.2.1 Attenuation.... 21
2.2.2 Noise and Interference ; 22
2.2.2.1 Sources of Noise 23
2.2.2.2 Relevance of Type of Noise 24
2.2.3 Distortion 24
2.2.3.1 Amplitude Distortion 25
v
vj Contents
2.2.3.2 Phase Distortion or Delay Distortion... 26
2.2.3.3 Harmonic Distortion .............28
2.2.4 Cross-Talk, Echoes, and Singing 29
2.3 What Is Done about These Problems 30
2.4 Digital Advantage 31
2.5 Digital Signal ••31
2.6 Processing of Digital Signal...... 32
2.7 Channel Capacity in Digital Technology 34
2.8 Advantages of Digital Technology 35
2.8.1 Universality of Components and Media 35
2.8.2 Cheap and Reliable Storage 36
2.8.3 Low Cost of the Equipment 36
2.8.4 Ease of Signaling 36
2.8.5 Use of Microprocessor 36
2.8.6 Less Precision Required 37
2.9 Disadvantages of Digital Technology 37
Review Questions ....38
Critical Thinking Questions 39
Bibliography • 39
3. Analog-to-Digital Conversion andTDM Principles....... ...41
3.1 Analog and Digital Signals 41
3.1.1 Continuous Time Analog Signal 41
3.1.2 Discrete Time Analog Signal 42
3.1.3 Digital Signal 42
3.1.4 Digital Signal Processing. ....44
3.2 Sampling Theorem.. ......45
3.3 (Analog) Pulse Modulation 46
3.3.1 Pulse Amplitude Modulation 47
3.3.2 Pulse Width Modulation..... 47
3.3.3 Pulse Position Modulation................................... 48
3.4 Digital Pulse Code Modulation .....i 49
3.4.1 Sampling 49
3.4.2 Quantization... : : 50
3.4.3 Quantization Noise 53
3.4.4 Companding 54
3.5 Other Digital Modulations 56
3.5.1 Differential PCM..... ....56
3.5.2 Delta Modulation 57
3.5.3 Adaptive Differential PCM : 57
3.5.4 Adaptive Delta Modulation ....
57
3.6 A/D and D/A Converters 58
3.6.1 A/D Converter 58
3.6.2 D/A Converter 58
3.6.3 Accuracy of A/D and D/A Conversion 60
Contents vii
3.7 Time Division Multiplexing 61
3.7.1 TDM/PCM 63
Review Questions 65
Critical Thinking Questions 67
Bibliography 67
4. Line Coding and Digital Modulation 69
4.1 Factors Affecting the Choice of Line Code 70
4.1.1 Timing Content 70
4.1.2 DC Wander 73
4.1.3 Bandwidth Requirement i 73
4.1.4 Power Consumption 75
4.1.5 Performance Monitoring Features 76
4.1.6 Error Probability 77
4.1.7 Cost 79
4.2 Types of Line Codes 79
4.2.1 Unipolar (RZ) Code (On-Off) 79
4.2.2 Polar (NRZ) Code 79
4.2.3 Alternate Mark Inversion Code (Bipolar Code) 80
4.2.4 High Density Bipolar-3 Code 81
4.2.5 Coded Mark Inversion Code 82
4.2.6 Manchester Code 83
4.2.7 Multilevel Line Codes 84
4.3 Digital Modulation Techniques 84
4.3.1 Amplitude Modulation (ASK) 85
4.3.1.1 Demodulation of Amplitude-ModulatedCarrier 85
4.3.2 Frequency Shift Keying 86
4.3.2.1 Demodulation of FSK Signals 87
4.3.3 Phase Shift Keying 87
4.3.3.1 Demodulation of PSK 88
4.3.4 Multiple Phase Shift Keying..... 89
4.3.5 Quadrature Amplitude Modulation 90
4.3.6 Digital Modulations for Optical Fiber Transmission 91
4.4 Other Means of Improving the Timing Content 92
4.4.1 Using Block Coding 92
4.4.2 Using Scrambler 93
4.4.3 Adding Redundant Bits 98
Review Questions — »»98
Critical Thinking Questions 100
Bibliography 100
5. Clock 101
5.1 What Is a Clock? 101
5.2 Significance of the Clock..........
102
viii Contents
5.2.1 Triggering the Events 102
5.2.2 Reception of Digital Bit Stream.....: 103
5.3 Clock Waveform 104
5.4 Types of Clocks 105
5.4.1 Multivibrator Clock 105
5.4.2 Crystal Oscillator Clock 106
5.4.3 Atomic Clocks : 107
5.5 Clock Accuracy Required in Communication Systems 108
Review Questions .-. •U0
Critical Thinking Questions HI
Bibliography •HI
6. Signal Impairments, Error Detection, and Correction 113
6.1 Types of Signal Impairments 114
6.2 Attenuation 114
6.3 Distortion 115
6.4 Intersymbol Interference 116
6.4.1 Effect of Pulse Shape on ISI 117
6.5 Jitter and Wander 120
6.5.1 Control of Jitter and Wander 123
6.5.1.1 Phase-Locked Loop ,......125
6.5.1.2 Elastic Store.
127
6.6 Eye Diagram 129
6.7 Error Detection 130
6.7.1 Use of Error Detecting Line Codes 131
6.7.2 Inserting Parity Bits 131
6.7.3 Through CRC 133
6.8 Error Correction 134
6.8.1 Repetition of Packets Containing Errored Bits
(Automatic Repeat Request) 134
6.8.2 Forward Error Correction 135
6.9 Link Performance ; 137
6.10 Required Link Performance 141
Review Questions * * 142
Critical Thinking Questions 143
Bibliography 144
7. Synchronization 145
7.1 Synchronization Process....
—146
7.1.1 Correct Detection of Symbols 147
7.1.1.1 Demodulation 147
7.1.1.2 Filtering 149
7.1.1.3 Amplification 149
7.1.1.4 Equalization and Pulse Shaping .....149
7.1.1.5 Decision Making 150
Contents ix
7.1.2 Timing Recovery and Clock Synchronization.... ....150
7.1.3 Framing ...152
7.1.4 Use of Multiframes 154
7.2 Synchronous vs. Asynchronous Systems 155
7.2.1 Asynchronous Systems.. 155
7.2.2 Synchronous Systems ,157
7.3 Synchronous Networks 158
7.4 Plesiochronous Networks 159
7.5 Slips • 161
7.6 Elastic Store and Controlled Slips 162
7.7 Line Synchronization vs. Networks Synchronization 164
7.8 Types of Network Synchronization 165
7.8.1 Master-Slave Synchronization 166
7.8.1.1 Using Primary and Secondary Reference
Clocks 166
7.8.1.2 By Timing Distribution through GPS 166
7.8.2 Mutual Synchronization 166
7.9 Pseudosynchronization.......; 167
7.9.1 Permitted Number of Slips in
PseudosynchronizationNetwork 168
7.9.2 Slip Rate Calculations 169
7.10 Synchronization Network Engineering (Planning a
Synchronous Network) 170
7.10.1 Network Synchronization Areas 171
7.10.2 Synchronization Chain 171
7.10.3 Master Clock SSUs and SECs 171
7.10.3.1 Master Clock (PRC) 171
7.10.3.2 Synchronization Supply Unit 173
7.10.3.3 SDH Equipment Slave Clocks 175
7.10.4 Typical Synchronous Network 175
7.10.5 Synchronization Principles and Timing Loops 177
7.10.5.1 Timing Loops 178
7.10.6 Synchronization Status Message 179
Review Questions 180
Critical Thinking Questions 183
Bibliography •183
8. Plesiochronous Digital Hierarchy 185
8.1 Pulse Code Modulation 186
8.1.1 Multiplexer 187
8.1.2 PCM/E1/2MB Multiplexing Structure 188
8.1.3 Time Slot 0 .....189
8.1.4 Multiframe.. 190
8.1.4.1 Time Slot 0 Details,
...190
8.1.5 Time Slot 16 191
X Contents
8.2 Higher-Order Multiplexing/Hierarchical Multiplexing.- 1938.2.1 E2 Multiplexing
. 1948.2.2 El Bit Rate Variation
1968.2.3 Justification or Bit Stuffing 1968.2.4 Number of Justification Bits 1988.2.5 Justification Control.....
1998.2.6 E2 Frame Structure
2018.2.6.1 Set I
2028.2.6.2 Sets Hand IE 2038.2.6.3 Set IV
2048.2.7 E2 Bit Rate and Bit Rate Adaptation of Els 2058.2.8 Bit Rate Adaptation......;. 2078.2.9 Positive/Negative Justification.. 2078.2.10 Variable Bit Rates of E2.. 207
8.3 E3 Multiplexing 2088.3.1 E3 Frame Structure
2098.3.1.1 Set I
. 2098.3.1.2 Sets H and ffl ..2098.3.1.3 Set IV
2098.3.2 Bit Rate Adaptation in E3 211
8.4 E4 Multiplexing 2118.4.1 E4 Frame Structure
2128.4.1.1 Set I
2128.4.1.2 Bit 13
2138.4.1.3 Bits 14 to 16
2138.4.1.4 Bits 17 to 488
2138.4.1.5 Set II to Set V.... 2138.4.1.6 Set VI
2148.4.2 Bit Rate Adaptation in E4 215
8.5 Higher Bit Rates2178.6 Framing Stages, Tributary Data, Overhead, and Payload Bits... 217
8.7 North American PDH Hierarchy 2188.8 Types of Line Codes used in PDH 2198.9 Synchronization in PDH
2198.9.1 Using Master-Slave Synchronization 2218.9.2 Using High-Accuracy Clocks ....2228.9.3 Clock Accuracy and Number of Slips in PDH Systems.... 2238.9.4 Current Trends
...2248.9.5 El Synchronization through Plesiochronous Network. 225
8.10 Asynchronous vs. Synchronous Multiplexing 2268.11 Skip Multiplexers
227Review Questions
228Critical Thinking Questions231
Bibliography..231
Contents
9. Plesiochronous Digital Hierarchy Maintenance Alarms .233
9.1 Types of Alarms •234
9.2 Loss of Signal -234
9.3 Loss of Framing 235
9.4 Alarm Indication Signal 237
9.5 Remote Defect Indication 238
9.6 Determination of Fault Location 239
9.7 Loss of Multiframe Alignment ••240
9.8 Multiframe Alignment AIS 241
9.9 Multiframe Alignment ••241
Review Questions \—; 247
Critical Thinking Questions 248
Bibliography • •248
10. Synchronous Digital Hierarchy 249
10.1 Evolution of Synchronous Digital Hierarchy 249
10.2 Advantages of SDH 252
10.2.1 Data Rates 252
10.2.2 Direct Drop/Insert of Tributaries 253
10.2.3 Automatic Protection Switching/Self-Healing 253
10.2.4 Compatibility with the Prevailing Standards 253
10.2.5 Vendor Compatibility 254
10.2.6 Compatibility with Data Communication Protocols 254
10.2.7 Excellent Operations, Administration, and
Management 255
10.3 Price to Be Paid for the Advantages 255
10.3.1 Establishing Timing Distribution throughout the
Network 255
10.3.2 Added Jitter Due to Pointer Adjustment 255
10.3.3 Poorer Framing Efficiency 256
10.3.4 Virus Threat........ 256
10.4 Synchronous Transport Module 256
10.5 Formation of STM-1..... 258
10.5.1 Justification of El Tributaries ..259
10.5.2 Frame Rate of STM-1 259
10.6 Container 262
10.7 Mapping... ; •
264
10.8 Virtual Containers 266
10.8.1 Data Rates 266
10.9 Path and Section.................. 268
10.9.1 Regenerator Section Overhead... 270
10.9.2 Multiplex Section Overhead 270
10.9.3 Section Overhead. 270
10.9.4 Path Overhead 270
xii Contents
10.10 SDH Layers .- .v...:...............271
10.11 Tributary Unit ..-272
10.12 Further Multiplexing 274
10.12.1 Bit Rates ...274
10.12.2 Tributary Unit Groups .....275
10.12.3 KLM Numbering 27610.12.4 Administrative Unit 277
10.13 Multiplexing of Higher-OrderPDH Tributaries .....280
10.13.1 Multiplexing Structure of E4 280
10.13.2 Multiplexing of E2 Rate (8.448 Mbps) 282
10.13.3 Multiplexing Routes 28210.13.4 Significance of AUG :
.283
10.14 Complete SDH Multiplexing Structure ...28310.14.1 STM-O 284
10.15 Frame Structure of STM-1 ...286
10.16 Pointer -28810.16.1 AU Pointer 288
10.16.1.1 Floating Frames 292
10.16.2 TU Pointer.. 295
10.16.2.1 Functioning and Purpose .. ; ..../29610.16.3 Summary of Pointer Advantages 297
10.16.4 Disadvantages of Pointer.................. 29810.16.5 AU-4 Pointer Details 299
10.16.5.1Justifications and Pointer Adjustment 30110.16.5.2New Data Flag 303
10.16.6 Bit Rate Adjustment Range of Pointer 30410.16.7 AU-3 Pointer 305
10.16.8 Details of TU Pointer.306
10.17 Formation of Higher-Order STMs 308
10.17.1 AUG Level Multiplexing 308
10.17.2 STM-1 Level Multiplexing 309
10.18 Frame Structure of Higher-Order STMs 310
Review Questions 311
Critical Thinking Questions..... 314
Bibliography • 315
11. Operations and Maintenance in SDH 31711.1 Performance Monitoring 318
11.1.1 Systems Out-of-Service Performance Monitoring 318
11.1.2 In-Qrcuit Performance Monitoring 319
11.1.2.1 Parity Check 321
11.1.2.2 Indications Generated by Parity Bytes 324
11.2 Fault Diagnostics and Restoration.
327
11.2.1 Loss of Signal 327
11.2.2 Loss of Framing 327
Contents xiii
11.2.3 Alarm Indication Signal 328
11.2.4 Remote Defect Indication 329
11.2.4.1 Higher-Order Path Remote Defect Indication 329
11.2.5 Further Transmission of AIS to AU +TU Levels 330
11.2.6 Multiplex Section Excessive Errors 331
11.2.7 Loss of Pointer (AU-LOP and TU-LOP) ,332
11.2.8 Higher-Order Path Unequipped and Lower-OrderPath Unequipped 333
11.2.9 Trace Identifier Mismatch 333
11.2.10 Signal Label Mismatch ..334
11.2.11 Tributary Unit Loss of Multiframe i 334
11.3 Summary of SDH Alarms and Indication... 334
11.3.1 SDH Performance Indicators 334
11.3.1.1 Anomaly .337
11.3.1.2 Defect 337
11.3.1.3 Failure 337
11.4 Performance Monitoring Parameters 337
11.4.1 Error Performance Objectives 339
11.5 Roles of Other Overhead Bytes 340
11.5.1 SOH Bytes 340
11.5.1.1 Bytes El (RSOH) and E2(MSOH) 340
11.5.1.2 Byte Fl (User Channel) (RSOH) 341
11.5.1.3 Bytes Kl and K2 (MSOH). 341
11.5.1.4 Byte SI (Synchronization Status Message
Byte)..... 341
11.5.1.5 A Bytes (RSOH): Media-Dependent Byte ;.342
11.5.1.6 Bytes X (Reserved for National Use) 342
11.5.1.7 Bytes Dl to D12: Data Communication
(DCC) Bytes............. 342
11.5.1.8 Unmarked Bytes i 342
11.6 Overhead Bytes Summary 342
11.6.1 Regenerator Section Overhead 343
11.6.2 Multiplex Section Overhead ..344
11.6.3 Higher-Order Path Overhead 344
11.6.4 Lower-Order Path Overhead.. 346
11.7 Network Management in SDH 346
11.7.1 Network Management System 347
11.7.1.1 Distributed Control..... 347
11.7.1.2 Distributed Authorization 348
11.7.1.3 Customer-Managed Links 349
11.7.2 Complete Telecommunications Network Management ....349
11.7.3 NMS Activities 349
11.7.3.1 Configuration .........350
11.7.3.2 Provisioning....... 351
11.7.3.3 Performance Monitoring 352
&v Contents
11.73.4 FaultDiagnostics and Management Alarms 353
11.7.3.5 Security ; 353
11.7.3.6 Tuning Management 35411.7.3.7 Maintenance Operations 354
Review Questions 355Critical Thinking Questions 357
Bibliography...*...... • 358
12. SDH Architecture and Protection Mechanism~
35912.1 SDH Network Elements 360
12.1.1 Terminal Multiplexer ..
36012.1.2 Regenerator 36112.1.3 Add/Drop Multiplexer.... . 36112.1.4 Digital Cross Connect 362
12.1.4.1 Higher-Order Cross Connect 362121.4.2 Lower-Order Cross Connect 362
12.2 SDH Network Topologies .. 36312.3 Work and Protect Paths 36512.4 Advantage of a Ring —366-12.5 Protection Switching Schemes 367
12.5.1 1 + 1 Protection Scheme 36712.5.2 1:1 Protection Scheme 36912.5.3 1:N Protection Scheme 369
12.6 Self-Healing Rings : 37112.7 Types of Automatic Protection Switching 37112.8 MS Dedicated Ring Protection 37212.9 MS Shared Ring Protection 373
12.9.1.1 Principles of Working 374
12.9.1.2 Switching Mechanism 37712.9.2 Commands for Protection Switching 382
12.9.2.1 Commands Activated through Kl Byte 38212.9.2.2 Commands Activated through K2 Byte .385
12.10 Other Important Features of Protection Switching 38612.10.1 Switching Time .386
12.10.2 Switching Initiation Time. 387
12.10.3 Operation Mode 387
12.10.4 Switching Protocol 387
12.10.5 Manual Controls, 387
12.10.6 Misconnection.... 38812.10.7 Squelching 38812.10.8 Nonpreemptible Unprotected Traffic (NUT) 388
12.10.9 DXC Byte Commands .38912.11 Subnetwork Connection Protection 389
12.11.1 Principles of Working 39012.11.2 Switching Mechanism 390
Contents xv
12.11.3 Other Important Features..... 392
12.12 Comparison of Various Protection Schemes 392
12.13 Deployment of Protection in a Network... 393
Review Questions 395
Critical Thinking Questions 397
Bibliography 397
13. Data Over SDH 399
13.1 Problems in Interfacing Data and SDH 401
13.1.1 Difference in the Bit-Stream Structure 401
13.1.2 Difference in Signaling (Protocol) J. 401
13.1.3 Difference in Throughput Rate 402
13.2 Data as Payload 402
13.3 Concatenation 403
13.4 Contiguous Concatenation 405
13.5 Mapping of ATM Frames 407
13.5.1 ATM Mapping in VC-4. 408
13.5.2 ATM Mapping in VC-2 409
13.6 Mapping of HDLC, PPP, Ethernet, IP, and LAPS 410
13.7 Shortcomings of Data over SDH i.: 411
13.7.1 Requirement of Concatenation Feature 411
13.7.2 Inefficient Capacity Utilization 412
13.7.3 Stuffing Bytes Requirement 412
13.7.4 Handling of Multiple Protocols 412
Review Questions • 412
Critical Thinking Questions 413
Bibliography 414
14. Emerging Systems and the Future of SDH 415
14.1 Case for Ethernet Backbone 416
14.2 SDH's Fight 418
14.3 Next-Generation SDH 418
14.3.1 Virtual Concatenation 419
14.3.1.1 V-CAT Procedure 419
14.3.1.2 Mapping of 10-Mbps Ethernet 420
14.3.1.3 Efficiencies of Other Services 421
14.3.1.4 Resilience through V-CAT 423
14.3.1.5 Payload Identification and Realignment 423
14.3.1.6 Payload Identification and Realignment in
LO-V-CAT 427
14.3.2 Link Capacity Adjustment Scheme 428
14.3.2.1 Improving the Link Reliability (Resilience) 429
14.3.2.2 Automatic Removal of Failed Members 429
14.3.2.3 In-Service Resizing of Bandwidth 430
14.3.2.4 Provisioning of Asymmetric Bandwidth. 431
xviContents
14.3.2.5 Working with Non-LGAS Nodes 43114.3.2.6 LCAS Operation (Higher Order) 43114.3.2.7 Lower-Order LCAS...
, .......43314.3.3 Generic Framing Procedure 434
14.3.3.1 What Is GFP?435
14.3.3.2 Advantages of GFP 43614.3.3.3 GFP Frame Structure
43814.3.3.4 GFP Mapping 43914.3.3.5 Frame-MappedGFP
„ 43914.3.3.6 Transparent Mapped GFP 44014.3.3.7 Comparison of GFP(F) and GFP(T) 441
14.4 Resilient Packet Ring 44214.4.1 Classes of Service in RPR 44314.4.2 Fairness Control
44414.4.3 Protection in RPR
44414.4.4 RPR Management 444
14.5 New-Generation Network Elements 44514.5.1 Multiservice Provisioning Platform 44514.5.2 Multiservice Switching Platform ........44514.5.3 Multiservice Transport Node 44514.5.4 Wave Length Division Multiplexing 44514.5.5 Optical Transport Network 44514.5.6 Carrier Ethernet
44514.6 What Is the Future, SDH or Packet Networks? 446Review Questions
448Critical Thinking Questions
450Bibliography
450
15. Transmission Media for PDH/SDH and OFC Technology 45315.1 Types of Media for PDH/SDH Transmission 45315.1.1 Copper Wire Pair
45315.1.2 Coaxial Cables
45515.1.3 Microwave Radios
45615.1.4 Free Space Optics (Air Fiber) .45715.1.5 Optical Fiber Cable
45815.2 Optical Fiber Communication Technology 459
15.2.1 Principles of OFC459
15.2.2 Optical Frequency/Wavelength Used 46115.2.3 Types of Optical Fibers
46315.2.3.1 Plastic Fiber
46315.2.3.2 Glass Fibers
46415.2.3.3 Multimode Fiber,
46415.2.3.4 Single Mode Fiber 46515.2.3.5 Dispersion-Shifted Fibers.. 46515.2.3.6 Step Index Fiber 466
Contentsxvii
15.2.3.7 Graded Index Fibers 46615.2.4 OFC System Components 467
15.2.4.1 Optical Source....... 46715.2.4.2 Photo Detector 469
15.3 All Optical Networks , 47115.3.1 Optical Amplifiers 47115.3.2 Wavelength Division Multiplexing ..472
.15.3.3 Optical Cross Connect 47415.3.4 Optical Add-Drop Multiplexer 474
15.4 OFC Link Budget 47515.4.1 Loss Margin
, 47715.4.2 Dispersion Limit 477
Review Questions ; 478Critical Thinking Questions 480Bibliography 481
16. Introduction to Optical Transport Networks 48316.1 OTH Principles 48516.2 Multiplexing Structure of OTN 485
16.2.1 Optical Payload Unit 48716.2.2 Optical Data Unit 48716.2.3 Optical Transport Unit
. 48716.2.4 Optical Channel 48716.2.5 Optical Channel Carrier 48716.2.6 Optical Channel Group 48716.2.7 Optical Transport Module 48816.2.8 Optical Multiplex Section 48816.2.9 Optical Transmission Section 488
16.3 Multiplexing Hierarchy of OTN 48816.4 OTN Layers 49216.5 OTN Domain Interfaces
49316.5.1 Intradomain Interface
49316.5.2 Interdomain Interface 493
16.6 Advantages of OTN494
16.6.1 Very High Link Capacity :. 49416.6.2 Forward Error Corrections 49416.6.3 Backward Compatibility with Existing Protocols 49416.6.4 Improved Efficiency for Data Traffic... 49416.6.5 Reduced Number of Regenerators 49516.6.6 Strong Management and Protection 49516.6.7 Quick Localization of Faults 495
16.7 Frame Structure of OTN 49616.7.1 Framing Bytes 49716.7.2 OTU Overhead
49716.7.3 ODU Overhead
, 499
xviii Contents
16.7A OPU Overhead. 502
16.8 Forward Error Correction. ..503
16.9 Operations and Maintenance in OTN .50616.9.1 Forward Defect Indication 506
16.9.2 Open Connections Indication ..50616.9.3 Locked 506
16.9.4 Payload Missing Indications 50616.10 Future of OTN 507
Review Questions 508
Critical Thinking Questions 510
Bibliography 510
Index 511