1 General Provisions
1.0.1 This specification is applicable to newly-built synchronous digital network engineering design. The expansion engineering shall be implemented with reference to the specification on the basis of taking full consideration of the former equipment.
1.0.2 The engineering design must conform to national guidelines and policies and adhere to scientificity, fairness and rationality.
1.0.3 The engineering design must meet the requirements of relevant national, professional and technical standards and shall be practical, economical, rational, and advanced in technology.
1.0.4 The synchronous network engineering design shall not only guarantee the quality of synchronous network regularly, but also guarantee the network operation safety in case of natural disasters and other special emergency. And the convenience of construction and maintenance, and the tidiness and beautifulness in computer room shall be taken into account.
1.0.5 The engineering design shall adapt to the developing and planning of communications network, give priority to recent service demand, take the service development demand into account, and create conditions for the expansion and transformation.
1.0.6 The synchronous equipment adopted in engineering design shall obtain the network access license issued by Ministry of Information Industry. The equipment which have not obtained the communication equipment network access license issued by MII shall not be used in the engineering.
1.0.7 The part that the specification is not involved in can be referred to "Technical requirements of Transport Network Based on SDH" (YD/T 1267 - 2003).
1.0.8 Under special conditions and in execution difficulty of individual provisions, they shall be sufficiently argued in design and approved by chief jurisdiction department.
2 Terms and Symbols
BITS Building Integrated Timing Supply
GPS Global Positioning System
GLONASS Global Navigation Satellite System
LPR Local Primary Reference
PDH Plesiochronous Digital Hierarchy
PRC Primary Reference Clock
SDH Synchronous Digital Hierarchy
SLM Synchronization Local Manager
SNM Synchronization Network Manager
SRM Synchronization Regional Manager
SSU Synchronous Supply Unit
SSU-T Synchronous Supply Unit-Transit Node
SSU-L Synchronous Supply Unit-Local Node
SSM Synchronization Status Message
STM Synchronous Transport Module
DCN Data Communication Network
TMN Telecmmunication Management Network
3 Basic Distribution Network Design
3.1 Network Composition and Class
3.1.1 Synchronous digital network shall adopt the network mode controlled by distributed multiple reference clock. The synchronous zone is divided according to province, autonomous region or municipality, a regional reference clock LPR is set in every synchronous zone, and master slave synchronization occurs in the same zone. To guarantee the safety and reliability of synchronous network, many sets of the entire network reference clock PRC are set in the entire network to provide guarantee of synchronous reference for the entire network.
3.1.2 The nodes of synchronous digital network are divided into three classes. Nodes of Class 1 adopt the reference clocks of Class 1, the nodes of Class 2 adopt the clocks of Class 2 and the nodes of Class 3 adopt the clocks of Class 3. Synchronous nodes at all levels are arranged in communications buildings at different levels in synchronous reference distribution network.
3.1.3 As for the synchronous network formed based on SDH, the main structures of its synchronous reference distribution are that of layered timing platform and the network should satisfy the requirements of Figure 3.13 and the following principles.
1. The timing source of interprovincial SDH transport layer is PRC; PRC and interprovincial transport compose the inter-provincial timing platform. 2. The timing source of provincial SDH transport layer is LPR or PRC; LPR or PRC and provincial SDH transport layer compose provincial timing platform jointly. 3. The timing source of local SDH transport layer is node clock of Class 2; the node clock of Class 2 and local SDH transport layer compose local timing platform jointly.
4. Node clocks of Class 3 and the communication service nodes (switching center, transmission nodes) obtain synchronous signals from local timing platform. 4.
3.1.4 Under normal conditions where satellite timing system is available, the main reference source of regional reference clock LPR are timing systems of satellite and the standby reference comes from PRC; where the timing system is unavailable, LPR is synchronous with PRC and PRC provides basic guarantee of synchronous reference for the entire network.
Figure 3.1.3 Block Diagram of Synchronous Digital Network
3.2 Arrangement of Synchronization Network Node
3.2.1 The function of all-leveled nodes of synchronous network is: to lock onto the trace of synchronous reference signal and to provide synchronous reference distribution for the inferior synchronization node and the communications service network element in the communication building of the node at the current class.
3.2.2 The arrangement principle of synchronization node clock at all levels
1. Reference clock at Class 1
The reference clocks of Class 1 are divided into the primary reference clock (PRC) and Local Primary Reference(LPR).
1) Primary Reference Clock (PRC): PRC is composed of Cesiuim atomic clock groups or of Cesiuim atomic clock groups and Satellite Positioning System (GlPS and/or GLONASS and other positioning system).PRC is the basic guarantee of primary synchronous reference and the arrangement of PRC shall meet the following requirements:
- The arrangement quantity and distribution should meet the requirement that an interprovincial SDH transport layer is equipped with synchronous reference sources from two different PRCs.
- The arrangement quantity and distribution of PRC shall facilitate the control of the wandering index of full-range entire network.
- PRC shall be arranged in the communication building of interprovincial transport layer junction nodes.
2) Local Primary Reference (LPR): LPR is composed of satellite timing system (GPS and/or GLONASS and others and others positioning system, the same as is below) and atomic clocks of Rubidium. It can receive the synchronization of satellite positioning system and be synchronous with PRC, while LPR is the reference source of various provinces. The arrangement of LPR shall meet the following requirements:
-The arrangement quantity and distribution of LPR should meet the requirement that provincial SDH transport layer is equipped with synchronous reference sources from two different LPRs.
-In principle, every province is arranged with two LPR (if the province has been equipped with one PRC, and one LPR shall be arranged), which location is arranged in the communication building where the convergence node of interprovincial transport layer and provincial transport layer are located.
2. Secondary node clock (SSU-T)
Secondary node clock is the synchronization node where various prefectures and cities receive synchronous reference sources of LPR. The arrangement of secondary node clock shall meet the following requirements:
Contents
Foreword I
1 General Provisions
2 Terms and Symbols
3 Basic Distribution Network Design
3.1 Network Composition and Class
3.2 Arrangement of Synchronization Network Node
3.3 The Organization of Synchronous Timing Chain
3.4 Synchronous Reference Transport
3.5 Intercommunication of SSM Information of SDH Equipment
3.6 Interface Requirement
3.7 Intraoffice Distribution of Timing Reference
4 Network Management System Design for Synchronization Network
4.1 Structure of Network Management System
4.2 Communication Mode
4.3 Requirements of Basic Function for Network Management System
5 BITS Installation and Design
5.1 Basic Requirements of BITS Equipment
5.2 Layout and Installation of Equipment
5.3 Wiring Requirements
5.4 Power Supply and Earthing
Appendix A Main Performance Index of Synchronization Node Clock
Appendix B Basic Requirements of Monitoring and Management Functions for Synchronization Equipment BITS
Appendix C Explanation of Wording in This Code
