INTRODUCTION PDH & SDH

1. INTRODUCTION PDH & SDH On Job Training July 2006 PT Indonesia Comnets Plus

2. Agenda • Pre SDH (PDH) • SDH • The SDH Frame • Frame Structure • Overhead and Payload Analysis • Tributary Units • SDH Network Protection

3. Plesiochronous Digital Hierarchy

4. Multiplexing hierarchy • The PDH high capacity transmission networks are based on a hierarchy of digital multiplexed signals: E.1 to E.4. • The basic building block is the primary rate of 2.048 Mb/s (E.1). This could be made up of 30 x 64 Kb/s voice channels. This would then be multiplexed up to a higher rate for high capacity transmisson.

5. Four signals at the primary rate can be multiplexed up to the secondary rate, E.2, of 8.448 Mb/s and so on up to a rate of 139 Mb/s (E.4). • Thus the 139 Mb/s rate represents 64 x 2.048 Mb/s signals and 1920 multiplexed voice channels.

6. Developing networks • The plesynchronous multiplexing technology, often called PDH (Plesiochronous Digital Hierarchy), left no room in the signal structures for network management and maintenance functions. • We are therefore left with no spare signal capacity to provide improvements in the signal transmission.

7. As networks developed inter-connection became increasingly complex. It required banks of multiplexers and large, unreliable distribution frames. • It became clear that the original standards, designed for point-to-point links, were just not suitable.

9. Tributary access • We want to have easy access to an individual tributary, in order that it may be re-routed. • We cannot do this without having to demultiplex the whole signal down to the required tributary level. • Costs go up as we demultiplex, and they then double because we have to re-multiplex the signal back up again.

10. No commont standard • Before SDH there were no standards to ensure that equipment from different vendors interworked on the same system. • Vendors can have their own unique designs which means we have to buy the same vendor’s equipment for both ends of the line. • Ideally we would like to shop around for the most suitable equipment, without having to keep to the same supplier.

11. What we need • Network operating companies have to provide faster, cost effective provisioning of customer circuits and services, as well as control of transmission bandwidth.

12. SDH Definition • SDH is a standard for ‘high speed – high capacity’ optical telecommunication networks ; more spesifically a synchronous digital hierarchy. • It is a synchronous digital transport system aimed at providing a more simple, economic and flexible telecommunications network infrastructure.

13. Advantages of SDH • Designed for cost effective, flexible telecoms networking – based on direct synchronous multiplexing. • Provides built-in signal capacity for advanced network management and maintenance capabilities.

14. Provides flexible signal transportation capabilities – designed for existing and future signals. • Allows a single telecommunication network infrastructure – interconnects network equipment from different vendors

15. Where is SDH used ? • SDH can be used in all of the traditional network application areas. • A single SDH network infrastructure is therefore possible which provides an efficient direct interconnection between the three major telecommunication networks.

16. Notes on SDH rates • The most common SDH line rates in use today are 155.52 Mbps, 622.08 Mbps, 2.5 Gbps, 10 Gbps. • SDH is a structure that is designed for the future, ensuring that higher line rates can be added when required.

17. SDH signal structure • The SDH signal is transported as a synchronous structure which comprises a set of 8-bit bytes organised into a two dimensional frame. • The ‘Truck analogy’ is a popular way to help us understand the contents of the SDH frame.

18. SDH FRAME STRUCTURE TRUCK ANALOGY Payload Unit Tractor Unit

19. SDH FRAME STRUCTURE TRUCK ANALOGY contd. Regenerator Section OverHead Section Overhead Virtual Container Payload Multiplexer Section OverHead Payload OverHead

20. The Payload • The contents of the container carried by the truck represent the real value. • This ‘Payload’ is analogous to customer traffic, being carried by the ‘container’ within an SDH frame. • This Payload ‘container’ supports the transportation of spesific tributary signals.

21. The Section Overhead • What actually gets the contentsof the truck to it’s destination is the tractor unit. • This analogous to the network maintenance and management capability carried by the SDH frame, known as it’s Section OverHead, or SOH.

22. The Section Overhead (SOH) provides facilities that are required to support and maintain the transportation of customer traffic Safely across the network. • THE SOH is split into Multiplexer Section Overhead (MSOH) and Regenerator Section Overhead (RSOH).

23. The Virtual Container • Even if the container is loaded on to a different truck, there is a portion of overhead that always remains with it. • This is known as the Path OverHead, or POH. • The Path Overhead is directly associated with the payload capacity area, and together they form what’s known as the Virtual Container.

24. = 8 bits/byte SDH FRAME STRUCTURE STM-N FRAME STRUCTURE 270 x N Columns 9 Rows 261 x N Columns 9 x N Columns

25. SDH FRAME STRUCTURE signal frame transmission The principle for SDH signal frame transmission is: the bytes (8-bit) within the frame structure is transmitted byte-by-byte (bit-by-bit) from left to right and from top to bottom. After one row is transmitted, the next row will follow. After one frame is completed, the next frame will start

26. SDH FRAME STRUCTURE SDH Rate ITU-T defines the frequency to be 8000 frames per second for all levels in STM hierarchy STM-1 Rate : 9 rows x 270 columns x 8 bits/byte x 8000 frames per second = 155.52 Mb/s STM-4 Rate : 9 rows x (270 x 4) columns x 8 bits/byte x 8000 frames per second = 622 Mb/s

27. MSOH MSOH RSOH RSOH POH RSOH OVERHEAD ANALYSIS

28. OVERHEAD ANALYSIS PATH OVERHEAD • Path Trace message • Parity check • VC structure • Alarm & performance info • User channel • Multiframe indication for TUs • Path protection switching

29. OVERHEAD ANALYSIS PATH OVERHEAD contd. • J1 : Path Trace byte • B3: Path BIP8 Code • C2: Signal label byte • G1: Path status byte • F2, F3: Path user channels bytes • H4: TU position indicator byte • K3: Spare byte • N1: Network operator byte

30. ×1 Mapping AUG-64 STM-64 Aligning ×4 Multiplexing ×1 AUG-16 STM-16 Pointer processing ×4 ×1 AUG-4 STM-4 ×4 ×1 ×1 AU-4 VC-4 C-4 AUG-1 STM-1 139264 kbit/s ×3 TU-3 VC-3 C-3 ×1 TUG-3 34368 kbit/s ×7 TUG-2 TU-12 VC-12 C-12 Go to glossary 2048 kbit/s ×3 SDH Multiplexing Structure

31. 34 Mbit/s to STM-N VC3 C3 1 1 Add POH 1 Rate Adaptation Next page P O H 34M 9 9 Packing Mapping 84 85 1 1 125μs 125μs SDH Tributary Multiplexing (34M)

32. TU-3 TUG-3 VC-4 1 261 86 86 1 1 3 1 1 1 H1 H2 H3 H1 H2 H3 Fill gap 1st align P O H R R ×3 R 9 9 9 Aligning Stuffing Multiplexing Same as for C4 Multiplexing route:1X34M  1XTU-3  3XTUG-3  1XAU-4---One STM-1 can load three 34Mbit/s signals SDH Tributary Multiplexing (34M)

33. SDH Tributary Multiplexing (2M) 2 Mbit/s to STM-N TU12 VC12 C12 POH 1 4 1 4 1 4 1 1 1 Next page Add POH Rate Adaptation Add Pointer 2M 9 9 9 125μs Mapping Packing Aligning TU-PTR

34. TUG-3 TUG-2 86 1 1 12 1 1 R R ×7 ×3 9 9 Same as for C3 Multiplexing Multiplexing Multiplexing route: 1X2M  3XTU12  7XTUG-2  3XTUG-3  1XSTM-1--- One STM-1 can load 3X7X3 = 63X2M Signals Multiplexing structure: 3-7-3 structure SDH Tributary Multiplexing (2M)

35. SDH Network protection • Unidirectional Traffic • Traffic flow direction along the ring • Clockwise and counter-clockwise • Bidirectional Traffic • Traffic flow direction along the ring • Clockwise or counter-clockwis

36. Difference between Path and Multiplex Section

37. 1+1 Linear MS Protection • Protection mechanism of 1+1linear MS protection system: • Concurrent sending is permanent bridging • Selective receiving is switching

38. 1:N Linear MS Protection • Structure of 1:N Linear MS Protection

39. 1:1 Linear MS Protection • Protection mechanism of 1:1 linear MS protection system: • Traffic flow after protection switching

40. Two-fiber uni-directional path protection ring • Protection switching mechanism: • Switching criteria • Transmission quality of each individual channel • Usually TU-AIS, TU-LOP alarms

41. Two-fiber bidirectional Multiplex Section Shared Protection Ring • Traffic flow when network is broken: • Working channels=1-N/2 AU4 • Protection channesl=N/2-N AU4

42. Two-fiber bidirectional Multiplex Section Shared Protection Ring • APS controller: • Transition of APS controller status:

43. Four-fiber bidirectional Multiplex Section Shared Protection Ring • Structure: • Four fibers • Working channels--S1,S2, carry normal traffic • Protection channels--P1,P2, protect normal traffic

44. SubNetwork Connection Protection • Description: • Protection one SubNetwork Connection • Can be adapted to all networks

45. SubNetwork Connection Protection • Normal condition for unidirectional SNCP: • Concurrent sending (transmit end) • Selective receiving (receive end)

46. SubNetwork Connection Protection • Failure in working channels for unidirectional SNCP: • Concurrent sending (transmit end) • Selective receiving (receive end)

47. SubNetwork Connection Protection • Protection Restoration: • Restoration time - 10 minutes (5-12 minutes)