1 - SDH Basics
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© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
110-HTM000021-DSDH Basics
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Objective
Standards
Frame Structure
Multiplexing
Regenerator Section Overhead
Multiplex Section Overhead
Path Overhead
Advantages
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Plesiochronous Digital Hierarchy (PDH)
Notation Data Rate
E0 64 Kbps
E1 2048 Kbps
E2 8448 Kbps
E3 34368 Kbps
E4 139264 Kbps
Notation Data Rate
T0/DS0 64 Kbps
T1/DS1 1544 Kbps
T2/DS2 6312 Kbps
T3/DS3 44736 Kbps
T4/DS4 139264 Kbps
European Standard American Standard
• Used in South America, Europe, India etc
• Used in South America, Europe, India etc • Used in USA, Canada
Japan, Korea, Hong Kong etc
• Used in USA, Canada Japan, Korea, Hong Kong etc
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
SDH at glance:
1. SDH (Synchronous Digital Hierarchy) – Recommendation for Optical Telecomm. Networking formulated by ITU & can have line rate of 40Gbps.
2. SDH follows the Master-Slave clock technique with PLL to synchronize the nodes.
3. SDH provides mapping, MUXing (TDM) & framing to mainly carry PDH & Ethernet traffic to form STM frame.
4. Overhead bytes ensure the management of payload & Pointers allow dynamic allocation of payload in STM frame.
5. Automatic Protection Switching provide protection to traffic against the fiber cut & errors with the help of overhead bytes in SDH.
6. Performance Monitoring & Alarms strengthens SDH by giving sufficient indication using Overheads against errors like equipment, operator & comm.
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
The hierarchy is as follows:
Optical Signal Bit Rate Abbreviated as
STM-0 51.84 Mbps 51 Mbps
STM-1 155.52 Mbps 155 Mbps
STM- 4 622.080 Mbps 622 Mbps
STM-16 2488.320 Mbps 2.4 Gbps
STM-64 9953.280 Mbps 10 Gbps
STM-256 39813.12 Mbps 40 Gbps
Standards
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
TX END
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
RX END
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
STM-1 Frame Format
9 Rows
Administrative Unit
Capacity of theVirtual Container
+Pointers
1
2
3
4
5
6
7
8
9
RegeneratorSectionOverhead
MultiplexSection
Overhead
H3H1 H2Pointers
STM-1 = 270 Columns (2430 bytes)
H1H1 H1 H2 H2 H2 H3 H3H3
Frame =125µs Frame = 125µsFrame =125µs
Overhead width = 9 columns
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
STM-N Frame Format
Frame = 125µs
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Frame Format
STM - Section overhead and Administrative unit
Section overhead – Regenerator section overhead and Multiplex section overhead
Administrative unit – Virtual container and pointers
Virtual container - Payload and Path overhead information
1 Byte=8bits * 8000 frames/sec=64 Kbps
Payload
STM-N
Administrative unit
Pointer Virtual Container
Path overhead
Section Overhead
Regenerator Overhead
Multiplex overhead
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Mapping Elements
Container
Virtual Container
Tributary Unit
Tributary Unit Group
Administrative Unit
Administrative Unit Group
STM-N Frame
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
The Container (C)
– Basic packaging unit for tributary signals (PDH)
Mapping Elements
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
The Virtual Container (VC)
– Formation of the Container by adding of a POH (Path Overhead)
The Tributary Unit (TU)
– Is formed via adding a pointer to the VC
The Tributary Unit Group (TUG)
– Combines several TUs for a new VC
Mapping Elements
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
The Administrative Unit (AU)
– Is shaped if a pointer is allocated to the VC formed at last
The Syncronous Transport Module (STM-N)
– Formed by adding a Section Overhead (SOH) to AUs
Mapping Elements
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
SDH Multiplexing
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
SDH Multiplexing
9 X 261
743 6521 743 6521 743 6521
321
4321 9 rows
4 columns
TUG-2 9 X 12
TU – 12 9X4
TUG-3 9 X 84
POH
POH
POH
Stuffing and POH
TUG - 3TUG - 3TUG - 3
Section Over Head
(9 X 9)
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
A1 A1 A1 A2 A2 A2 J0
B1 E1 F1
D1 D2 D3
RegeneratorSection
Regenerator Section Overhead - RSOH
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Regenerator Section Overhead - RSOH
A1 A2 J0
B1 E1 F1
D1 D2 D3
Framing (A1,A2)
Start of the STM-1 frame.Section Trace or Future
Growth (J0)J0 carries section trace
message.
Local Orderwire (E1)Channel for voice
communications between any two NEs.
Section User Channel (F1)
A 64kb/s user channel.
Section BIP-8 (B1)Byte interleaved Parity-8
(BIP-8) is used for regenerator section error
monitoring.
Data communication channel (DCC_R)
Provides a single 192 kb/s channel for Management
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
B2 B2 B2 K1 K2
D4 D5 D6
D7 D8 D9
D10 D11 D12
S1 M1 E2
MultiplexSection
Multiplex Section Overhead - MSOH
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
B2 K1 K2
D4 D5 D6
D7 D8 D9
D10 D11 D12
S1 M1 E2
Line BIP-24 (B2)Byte interleaved Parity-24
(BIP-24) is used for multiplex section error
monitoring.
Multiplex Section Overhead - MSOH
Data Communication Channel (DCC-M)
Provides a single 576 kb/s channel for
ManagementAutomatic Protection Switch (APS) (K1,K2)Used for APS signaling
Synchronization status or Future growth (S1)
5-8 bits of the byte defines Synchronous status message
Line Remote Error Indicator (M1)
Remote error indication. Conveys the BIP-24 error count back to the source
Orderwire (E2)Orderwire channel for voice communication between two
NEs
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Pointers
SDH provides payload pointers to permit differences in the phase and frequency of the Virtual Containers (VC-N) with respect to the STM-N frame.
On a frame-by-frame basis, the payload pointer indicates the offset between the VC payload and the STM-N frame by identifying the location of the first byte of the VC in the payload.
The pointer value indicates the offset in bytes from the pointer to the first byte of the VC, which is the J1 byte.
Starting points are at 3-byte increments for a VC-4 payload, the possible range is: Total STM-1 bytes – Section Overhead bytes = Pointer value range
(2430 – 81)/3 = 783 valid pointer positions
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
For a VC-4 payload, this pointer is located in columns 1 and 4 of the fourth row of the Section Overhead
For a VC-3 payload, entire pointer bytes are used.
Pointers Continued
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Pointers Continued
The pointer value, is carried in bits 7 through 16 of the H1-H2 pointer word.
The first four bits, the N-bits, are known as the New Data Flag.These bits contains the pattern 0110 by default to indicate “No Arbitrary Change”.In case of “Arbitrary Change” pattern is 1001.
1 2 3 4 S1 S2 I D I D I D I D I D
New Data Flag Size Bits
Pointer Values (0 – 782)
0110 No Arbitrary change
1001 Arbitrary change
H1+H2
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Positive Pointer Justification (PPJ)
RSOH
MSOH
AU Pointer
Virtual Container (VC)
Data
When the data rate of the VC is too slow in relation to the rate of the STM-1 frame, then I bits are inverted & the pointer value is incremented by 1. This is known as PPJ.
Positive Pointer Justification (PPJ)
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Positive Pointer Justification (PPJ)
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
PPJ Example
For block 256 in frame n
Tx END (H1 H2 bytes)
0110 10 0100000000 frame n+1 initialization
0110 10 1110101010 frame n+2 I bits inverted,same ptr value
1block stuffed after H3 byte.
0110 10 0100000001 frame n+3 pointer value increased by 1
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
PPJ Example continued
Rx END 256 in frame n
0110 10 0100000000 frame n+1 initialization
0110 10 1110101010 frame n+2 I bits inverted (5/5,4/5,3/5) to get
pointer value 256
0110 10 0100000001 frame n+3 ptr value changed to 257
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
RSOH
MSOH
AU Pointer
Virtual Container (VC)
Negative Pointer Justification (NPJ)Data
When the data rate of the VC is too fast in relation to the rate of the STM-1 frame, D bits are inverted and the pointer value is decremented by 1. This is known as NPJ.
Negative Pointer Justification (NPJ)
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Negative Pointer Justification (NPJ)
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
NPJ Example
Tx END 642 block in frame n
(H1 H2 bytes)
0110 10 1010000010 frame n+1 initialization
0110 10 1111010111 frame n+2 D bits inverted,same ptr value,H3 bytes used.
0110 10 1010000001 frame n+3 ptr value changed to 641
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
NPJ Example continued
Rx END 642 block in frame n
0110 10 1010000010 frame n+1 initialization
0110 10 1111010111 frame n+2 D bits inverted (5/5,4/5,3/5)
to get ptr value 642
0110 10 1010000001 frame n+3 ptr value changed to 641
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
J1
B3
C2
G1
F2
H4
F3
K3
N1
Higher Order Path Overhead – HPOH(VC-4 / VC-3)Higher Order Path Overhead – HPOH(VC-4 / VC-3)
Path Overhead
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
J1
B3
C2
G1
F2
H4
F3
K3
N1
Path Signal Label (C2)
Indicates the type of payload in AU
Path Trace (J1)
J1 byte carries the trace information at path level
Path BIP-8 (B3)
Path error monitoring
Path Status (G1)
Provides status and performance information back to the remote end
Indicator byte (H4)
Carries multiframe information
Path User Channel (F2)
User data channel at path levelPath User Channel (F3)
User data channel at path levelBits 1-4 are allocated for
APS. Bits 5-8 are for future use.
Tandem Connection (N1)
IEC for tandem connection monitoring at
TCM source.
Higher Order Path Overhead – HPOH(VC-4 / VC-3)Higher Order Path Overhead – HPOH(VC-4 / VC-3)
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Lower Order Path Overhead – POH(VC-11 / VC-12)
VC-12 VC-11
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Lower Order Path Overhead - POH
V5
J2
N2
K4
Signal Label and parity check
Path Trace (J2)
J2 byte carries the trace information at lower order
path level
Tandem Connection (N2)
IEC for tandem connection monitoring at
TCM source.
Carries APS information at lower order path level
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Advantages
High speed standards
Efficient Multiplexing / Demultiplexing
Enhanced Operation, administration, Provisioning, Maintenance
capabilities (OAM&P)
Tejas Supports Next Generation SDH
Supports data(Ethernet) as well as voice.
No need for separate data infrastructure.
Use of GFP, VCAT, LCAS, Auto Negotiation.
© Tejas Networks India Ltd., 2007, Proprietary Information Rev1.2 Last update 11 Dec 07 Reviewed by:
Thank You…