CONTENTS

Introduction  
1 Scope
2 References
3 Terms and definitions
4 Acronyms and abbreviations
5 Conventions
6 Basic Multiplexing principles
6.1 Multiplexing structure
6.2 Basic frame structure
6.2.1 Section overhead
6.2.2 Administrative Unit pointers
6.2.3 Administrative Units in the STM-N
6.2.4 Maintenance signals
6.3 Hierarchical bit rates
6.4 Interconnection of STM-Ns
6.5 Scrambling
6.6 Physical specification of the NNI
6.7 Frame structure for 51 840 kbit/s interface
7 Multiplexing method
7.1 Multiplexing of Administrative Units into STM-N
7.1.1 Multiplexing of Administrative Unit Groups (AUGs) into STM-N
7.1.2 Multiplexing of an AU-4 via AUG
7.1.3 Multiplexing of AU-3s via AUG
7.2 Multiplexing of Tributary Units into VC-4 and VC-3
7.2.1 Multiplexing of Tributary Unit Group-3s (TUG-3s) into a VC-4
7.2.2 Multiplexing of a TU-3 via TUG-3
7.2.3 Multiplexing of TUG-2s via a TUG-3
7.2.4 Multiplexing of TUG-2s into a VC-3
7.2.5 Multiplexing of a TU-2 via TUG-2s
7.2.6 Multiplexing of TU-1s via TUG-2s
7.3 AU-n/TU-n numbering scheme
7.3.1 Numbering of AU-4s in an STM-N signal
7.3.2 Numbering of TU-3s in a VC-4
7.3.3 Numbering of TU-2s in a VC-4
7.3.4 Numbering of TU-12s in a VC-4
7.3.5 Numbering of TU-11s in a VC-4
7.3.6 Numbering of AU-3s in an STM-N signal
7.3.7 Numbering of TU-2s in a VC-3
7.3.8 Numbering of TU-12s in a VC-3
7.3.9 Numbering of TU-11s in a VC-3
8 Pointers
8.1 AU-n pointer
8.1.1 AU-n pointer location
8.1.2 AU-n pointer value
8.1.3 Frequency justification
8.1.4 New Data Flag (NDF)
8.1.5 Pointer generation
8.1.6 Pointer interpretation
8.1.7 AU-4 concatenation
8.2 TU-3 pointer
8.2.1 TU-3 pointer location
8.2.2 TU-3 pointer value
8.2.3 Frequency justification
8.2.4 New Data Flag (NDF)
8.2.5 Pointer generation
8.2.6 Pointer interpretation
8.3 TU-2/TU-1 pointer
8.3.1 TU-2/TU-1 pointer location
8.3.2 TU-2/TU-1 pointer value
8.3.3 TU-2/TU-1 frequency justification
8.3.4 New Data Flag (NDF)
8.3.5 TU-2/TU-1 pointer generation and interpretation
8.3.6 TU-2 concatenation
8.3.7 TU-2/TU-1 sizes
8.3.8 TU-2/TU-1 multiframe indication byte
9 Overhead bytes description
9.1 Types of overhead
9.1.1 SOH
9.1.2 Virtual Container POH
9.2 SOH description
9.2.1 SOH bytes location
9.2.2 SOH bytes description
9.2.3 Reduced SOH functionalities interface
9.3 POH descriptions
9.3.1 VC-4-Xc/VC-4/VC-3 POH
9.3.2 VC-2/VC-1 POH
9.3.2.5 Reserved: K4 (b5-b7)
10 Mapping of tributaries into VC-n
10.1 Mapping of G.702 type signals
10.1.1 Mapping into VC-4
10.1.2 Mapping into VC-3
10.1.3 Mapping into VC-2
10.1.4 Mapping into VC-12
10.1.5 Mapping into VC-11
10.1.6 VC-11 to VC-12 conversion for transport by a TU-12
10.2 Mapping of ATM cells
10.2.1 Mapping into VC-4-Xc
10.2.2 Mapping into VC-4/VC-3
10.2.3 Mapping into VC-2-mc
10.2.4 Mapping into VC-2
10.2.5 Mapping into VC-12/VC-11
Annex A - Recommended frame structure for digital section operating at 51 840 kbit/s
Annex B - CRC-7 polynomial algorithm
B.1 Multiplication/division process
B.2 Encoding procedure
B.3 Decoding procedure
Annex C - VC-4-Xc/VC-4/VC-3 Tandem Connection Monitoring protocol: option 1
C.1 Tandem Connection Overhead Byte location
C.2 Definitions
C.3 Tandem Connection Bundling
C.3.1 Bundling of VC-3s within an STM-1
C.3.2 Bundling of VC-3s within an STM-N (N>1)
C.3.3 Tandem Connection Bundle Contents
C.3.4 Tandem Connection bundles in higher rate signals
C.4 Incoming Error Count (IEC)
C.5 B3 Compensation
C.6 Data link
C.6.1 Format of the LAPD messages
C.6.2 Tandem Connection Trace, Idle Signal, and Test Signal Identification Messages
C.6.3 The far-end performance report message
C.6.3.1 Elements of the far-end performance report message
C.6.3.2 Tandem Connection error event
C.6.3.3 Tandem Connection AIS/LOP defect
C.6.3.4 Tandem Connection AIS failure
C.6.3.5 Tandem Connection LOP failure
C.6.3.6 Tandem Connection Idle signal received condition
C.6.3.7 Tandem Connection Test signal received condition
C.6.3.8 Tandem Connection Count Type Indicator
C.6.4 Special carrier applications
C.7 Treatment of Incoming Signal Failures
C.7.1 Signal failures before the Tandem Connection
C.7.2 Signal failures within the Tandem Connection
C.8 Tandem Connection Idle Signal
C.9 Tandem Connection test signal
Annex D - VC-4/VC-3 Tandem Connection Monitoring protocol: option 2
D.1 N1 byte structure
D.2 TCM functionality at the Tandem Connection source
D.3 TCM functionality at the Tandem Connection sink
D.4 BIP-8 compensation
Annex E - VC-2/VC-1 Tandem Connection Monitoring protocol
E.1 N2 byte structure
E.2 TCM functionality at the Tandem Connection source
E.3 TCM functionality at the Tandem Connection sink
E.4 BIP-2 compensation
Appendix I - Relationship between TU-2 address and location of columns within a VC-4
Appendix II - Relationship between TU-12 address and location of columns within a VC-4
Appendix III - Relationship between TU-11 address and location of columns within a VC-4
Appendix IV - Relationship between TU-2 address and location of columns within a VC-3
Appendix V - Relationship between TU-12 address and location of columns within a VC-3
Appendix VI - Relationship between TU-11 address and location of columns within a VC-3
Appendix VII - Enhanced Remote Defect Indication (RDI)
VII.1 VC-4-Xc/VC-4/VC-3 paths
VII.2 VC-2/VC-1 paths
Appendix VIII - A possible future definition of MS-REI