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

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

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 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 Mb/s and so on up to a rate of 139 Mb/s (E.4).
Thus the 139 Mb/s rate represents 64 x 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
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 Mbps, 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. Regenerator Section OverHead Multiplexer Section OverHead
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. SDH FRAME STRUCTURE STM-N FRAME STRUCTURE 270 x N Columns
= 8 bits/byte
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
= 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. OVERHEAD ANALYSIS
MSOH
POH
RSOH

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. SDH Multiplexing Structure
STM-1
AU-4
TU-3
AUG-1
TUG-3
VC-3
C-3
VC-4
C-4
TU-12
VC-12
C-12
TUG-2 ×1 ×3 ×7
kbit/s
34368 kbit/s
2048 kbit/s
Pointer processing
Multiplexing
Mapping
Aligning
AUG-4
AUG-16
AUG-64
STM-4
STM-16
STM-64 ×4
Go to glossary
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31. SDH Tributary Multiplexing (34M)
34 Mbit/s to STM-N
34M
Rate Adaptation
Add POH 1 C3 84 9
125μs
VC3 P O H 85
Next
page
Packing
Mapping
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32. SDH Tributary Multiplexing (34M)
1st
align
Fill
gap 1 86 9 H1 H2 H3 R ×3
TU-3 P O H
VC-4
261
Aligning
Stuffing
TUG-3
Multiplexing 3
Same as for C4
Multiplexing route: 1X34M  1XTU-3  3XTUG-3  1XAU-4---One STM-1 can load three 34Mbit/s signals
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33. SDH Tributary Multiplexing (2M)
2 Mbit/s to STM-N
TU12
C12
VC12
POH 1 4 1 4 1 4 1 1 1
Next
page
Add POH
Rate Adaptation
Add
Pointer 2M 9 9 9
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Packing
125μs
Mapping
Aligning
TU-PTR

34. SDH Tributary Multiplexing (2M)×3 1 12
TUG-2 9 ×7 R
TUG-3 86
Multiplexing
Same as for C3
Multiplexing route: 1X2M  3XTU12  7XTUG-2  3XTUG-3  1XSTM-1--- One STM-1 can load 3X7X3 = 63X2M Signals
Multiplexing structure: structure
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35. SDH Network protection
Bidirectional Traffic
Traffic flow direction along the ring
Clockwise or counter-clockwis
Unidirectional Traffic
Traffic flow direction along the ring
Clockwise and counter-clockwise

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)