sdh principle
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BASIC PRINCIPLE
SDH
1 、 SDH Basic Concept
2 、 Frame Structure And SOH
3 、 Multiplexing And Mapping
4 、 Synchronous Multiplexing System
5 、 SDH Self-healing Network
6 、 Clock And Timing
Summary
SDH Basic Concept
1 、 PDH Disadvantage — Lack of international uniform rate
2M Series : 2M 、 8M 、 34M 、 140M 、 565M ; 1.5M Series : North American : 1.5M 、 6.3M 、 45M 、 274M
Japan : 1.5M 、 6.3M 、 32M 、 100M ; — Lack of international uniform optical interface standard
—Add/Drop Service need a count of hardware and the Structure is complicated
— Multiplexing/De-Multiplexing need hardware step by step
— Network OAM&P capability is faultiness
SDH Basic Concept
400Mb/s
100Mb/s
32Mb/s
6.3Mb/s
series ofJapan
274Mb/s
45Mb/s
6.3Mb/s
565Mb/s
139Mb/s
34Mb/s
8Mb/s
2 Mb/s 1.5Mb/s
series of North America
series ofEurope
×4 ×4
×4
×4
×4
×4
×3
×5
×6
×7
×4
1.5Mb/s
PDH System:
SDH Basic Concept
140/34Mbit/s 34/140Mbit/s
/
Optical
signal/34/8Mbit/s 8/34Mbit/s
8/2Mbit/s 2/8Mbit/s
2Mbit/s
m
ultiplex
mu
ltiplex
mu
ltiplex
de multiplex
de
mu
ltiplex
de m
ultiplex
optic
al
electrical
electrical
optica
l
Optical
signal
SDH Basic Concept
THE PROCESS OF ADDING / DROPPING TRIBUTARIES IN PDH
PDH System:
• Faster transmission speed and more enormous capability.
• More efficient multiplexing and de-multiplexing.
• Worldwide uniform optical Network Node Interface(NNI).
• Self-healing functions of transmission network.
• Powerful Operation, Administration&Maintenance(OAM)
SDH Basic ConceptRequirements Of Modern Transmission Network
2 、 SDH Character: Advantages : — Uniform Rate : 155M 、 622M 、 2.5G 、 10G ;
— Uniform Optical interface and Frame Structure:
STM-N ( N=1 、 4 、 16 、 64 );
— Add/Drop service only by one step;
— Powerful Network OAM&P capacity
— flexible networking ,the survivability of network is powerful ;
— forward and backward compatibility 。
Disadvantage :
— The using percentage of the bandwidth is low
SDH Basic Concept
3 、 SDH Basic Concept
3.1 、 Hierarchy and Rate
kinds
STM-1
STM-4
STM-16
STM-64
rate ( Mb/s ) 155.520
622.080
2488.320
9953.280
63
252
1008
4032
Numbers of 2M
SDH Basic Concept
3.2 、 SDH Network Topology
. Line network
TM ADM ADM TMREG
. Tree network
TM ADM ADM TMREG
ADM
TM
SDH Basic Concept
. Ring networkADM
ADM
ADM ADM
SDH Basic Concept
. Star network
TM DXC ADM TMREG
ADM
TM
TM
ADM
TM
TM
SDH Basic Concept
. Mesh network
ADM
ADM
ADM
ADM
SDH Basic Concept
Frame Structure And SOH
SOH : Segment overhead
AU PTR : AU management pointer
POH : Path overhead
9×270×N Byte
1
345
9
SOH
STM-N Payload(including POH )
Direction
9×N 261×N270×N columns
SOH
AU PTR
T=125 us
Frame Structure And SOH
Payload
High order path layer
MSOH layer
Frame Structure And SOH
THE LEVELS OF SDH:
Low order path layer
RSOH layer
STM-N
1 、 STM-1 SOH Bytes arrangement
9 columns
A1 A1 A1 A2 A2 A2 J0
B1 E1 F1
D1 D2 D3
A U - P T R (AU management pointer)
B2 B2 B2 K1 K2
D4
D5 D6
D7 D8 D9
D10 D11 D12
S1 M1 E2
RSOH
MSOH
9
rows
Direction
T=125us
Frame Structure And SOH
2 、 SOH byte function 1. A1 、 A2 : initial frame position bytes;
2. J0 : Regenerating segment tracing byte ; 3. B1 : Bit insertion parity correction 8 bit codes (BIP-8)
.
B1 Byte
Verified byte
Verified byte
Verified byte
b1 b2 b3 b4 b5 b6 b7 b8
× × × × × × × ×
1 1 0 0 1 0 0 1
1
1
0 1 0 0 1 0 1
0 0 1 1 0 1 0
Frame Structure And SOH
4. D1~ D3 : RS Data communication channel ; 5. D4 ~ D12 : MS Data communication channel ; 6. E1 、 E2 : Order-wire bytes ; 7. F1 : User channel ; 8. B2 : BIP-N×24 code ; 9. K1 、 K2 : Automatic protection switching (APS)
Frame Structure And SOH
10. S1 : Synchronous status byte ; b5 ~ b8 = 0010 : G.811 Clock , 0100 : G.812 Clock , 1011 : Equipment Clock , 1111 : No usage 。11. M1 : (MS-REI) byte ,
Frame Structure And SOH
Multiplexing and Mapping
1 、 Multiplexing and mapping units
1.1 、 Container C
C is an important information structure in SDH, which mainly supports various digital flows.
There are three categories:
kinds
C-12
C-3
C-4
Signal category
2 Mb/s
34 / 45 Mb/s
140 Mb/s
Structure
9 × 4–2
9 × 84
9 × 260
Rate ( Mb/s ) 2.176
48.384
149.760
Multiplexing and Mapping
1.2 、 Virtual Container VC
VC also is an important information structure in SDH, which mainly supports the path layer connection.
There are three categories:
kinds
VC-12
VC- 3
VC- 4
Signal category
2 Mb/s
34 / 45 Mb/s
2/34/45/140 Mb/s
Structure
9 × 4–1
9 × 85
9 × 261
Rate ( Mb/s ) 2.240
48.960
150.336
Multiplexing and Mapping
VC-12 VC-3
POH
C-3 ( 34/45Mb/s )
85
POHC-12
( 2Mb/s )
4
9
Multiplexing and Mapping
C-4
( 140 Mb/s )
POH
261
9 3×TUG-3
( 2/34/45 M )
POH
261
9
VC-4 (a) VC-4 (b)
R
2
R
1
note : TUG3 = 7 × TUG -12= 21 × TU-12 ( 63 × VC12 ) TUG3 = TU - 3 ( VC-3 )
Multiplexing and Mapping
1.3 、 Tributary Unit TU
TU is an information structure that performs adaptation functions for the low order path layer and high order path layer 。
Kinds
TU-12
TU- 3
Including
VC12+ TU12 PTR
VC3+ TU3 PTR
Structure
9 × 4
9 × 85+3
Rate ( Mb/s ) 2.304
49.152
Multiplexing and Mapping
H1H2H3
TU PTR
VC-12 VC-39
TU-12 TU-3
4 85
9
Multiplexing and Mapping
1.4 、 Tributary unit Group (TUG)
One or more TUs with fixed locations form a TUG 。
Kinds
TUG- 3
Including
3 × TU-12
7 × TUG-2
Structure
9 × 12
9 × 86
Rate ( Mb/s ) 6.912
49.536
TUG- 2
Multiplexing and Mapping
3×TU - 12 7×TUG-2
( 1×TU- 3)
9
TUG-2 TUG-3
R means filled bytes
12 86
9RR
Multiplexing and Mapping
1.5 、 Administration unit-4 AU- 4
AU-4 Performs adaptation functions for the high order path layer and multiplexing segment layer 。 AU-4 consists of high order VC and AU PTR 。
AU-PTR VC - 4 9
261
9
Multiplexing and Mapping
2 、 Pointer
2.1 、 Purpose
— Indicate the position of payload
—Rate adjustment 。
2.2 、 Categories
Administration unit pointer AU PTR ; Tributary unit pointer TU-3 PTR 、 TU-12 PTR
Multiplexing and Mapping
3 、 AU PTR
3.1 、 Position and Structure
9
261
AU-PTR
9
H1Y Y H2 1* 1* H3 H3 H3
Y= 1001SS11
1*=11111111
VC - 4
Multiplexing and Mapping
3.2 、 H1 、 H2 、 H3 bit arrangement
N N N N S S I D I D I D I D I D
H1 H2 H3 H3 H3
NDF 10 bit pointer Negative adjustment
byte
AU
kinds
NDF : New data flag
SS : AU categories , SS=11 : AU-4
I : Increased bits
D : reduced bits
Multiplexing and Mapping
3.3 、 H1 、 H2 、 H3 byte function
. To indicate the position of Payload
. To adjust the rate of VC-4
. To indicate New Data flag (NDF)
Multiplexing and Mapping
4 、 TU-3 PTR
4.1 、 Position and Structure
H1H2H3 VC-3
9
85
TU-3
Multiplexing and Mapping
4.2 、 H1 、 H2 、 H3 bit arrangement
N N N N S S I D I D I D I D I D
H1 H2 H3
NDF 10 bit pointer Negative adjustment
byte
AU
kinds
NDF : New data flag
SS : AU categories , SS=00 : TU-3
I : Increased bits
D : reduced bits
Multiplexing and Mapping
4.3 、 H1 、 H2 、 H3 Byte function
. To indicate the position of Payload
. To adjust the rate of VC-3
. New data flag (NDF)
Multiplexing and Mapping
5 、 TU-12 PTR
5.1 、 Position and Structure
V1VC-12
V2 VC-12
V3 VC-12
500μs Multi-Frame
V4VC-12
Multiplexing and Mapping
5.2 、 V1 、 V2 、 V3 bit arrangement
N N N N S S I D I D I D I D I D
V1 V2 V3
NDF 10 bit pointer Negative adjustment
byte
AU
kinds
NDF : New data flag
SS : AU categories , SS=10 : TU-12
I : Increased bits
D : reduced bits
Multiplexing and Mapping
5.3 、 V1 、 V2 、 V3 Byte function
. To indicate the position of Payload
. To adjust the rate of VC-12
. New Data flag (NDF)
Multiplexing and Mapping
6 、 High Order VC-4 / VC-3 POH
6.1 、 Position and Structure
VC- 4 / VC-3
J1
B3
C2
G1
F2
H4
F3
K3
N1
Multiplexing and Mapping
6.2 、 POH Byte function
• J1 : High order path tracing byte; • B3 : High order path error code monitoring byte,BIP-8(code)
; • C2 : To represent the composition of VC-3/4 structure;
G1 : Path status byte : REI 、 RDI;• F2 、 F3 : User channel ;• H4 : To indicate the position of multi-frame;• K3 : Automatic protection switching (APS) byte ;• N1 : Network operator byte 。
Multiplexing and Mapping
7 、 Low Order VC-12 POH
7.1 、 Position and Structure V5VC-12
J2VC-12
500μs Multi-frame
VC-12N2
K4VC-12
Multiplexing and Mapping
7.2 、 Byte function
• V5 : Path status and signal tag byte ; b1b2 : Path bit insertion parity correction 8 bit codes (BIP-2); b3 : REI ; b4 : RFI ; b5b6b7 : signal category,Mapping mode;
b8 : RDI;• J2 : Low order path tracing byte ;
• N2 : Network operator byte ;
• K4 : Automatic protection switching (APS) byte 。
Multiplexing and Mapping
8 、 Byte Interleaving Multiplex
Adaptation of multiple low order path layer signals to high order path layer signal or multiple high order path layer signals to a multiplexing segment layer.
2
b
1 2 3 1 3 1 2 3
ca cba
TU-12 a TU-12 b TU-12 c
TUG-2
4 4 4
Multiplexing and Mapping
9 、 Mapping
9.1 、 Mapping
The process of putting various tributary signals into related VC is called mapping 。 For example:Putting 2Mb/s signal into VC-12 ; Putting 34 ( or45 ) Mb/s signal into VC-3 ; Putting 140Mb/s signal into VC-4 。
Multiplexing and Mapping
10 The mapping and multiplexing Structure
C 4
Adjustment
AUG
TUG-2
VC-3 C-3
TU-12 VC-12 C-12
( 140M )
( 34M / 45M)
( 2M )
Pointer processMapping
Multiplexing
×N
×7
×3
×3
TUG3
STM-N AU-4 VC-4
TU - 3×1
×1C-4
Multiplexing and Mapping
STM-N
× N × 1C-12VC-12VC-4 TUG-2AUG-4 AU-4 TU-12 2Mb/s
bit rate adjustment
LO POH
TU PTR
AU PTR× 3 multiplex
×7multiplex
HO POH
× 3 multiplex
N×multiplex
TUG-3
Multiplexing and MappingTHE JOURNEY OF 2Mbit/s IN STM-N
Synchronous Multiplexing System
1 Synchronous Multiplexing Equipment Categories
. Terminal Multiplexer (TM)
In the end station of chain network, TM is used to multiplex/de-multiplex the PDH/SDH tributary signals to/from line SDH signal.
PDH/SDH tributary signal
OAM
Line signal
STM-N
TM
Synchronous Multiplexing System
. Add/Drop Multiplexer (ADM)
ADM is placed in the middle station of the network , which performs to add/drop service function 。
STM-NSTM-N
West signal
PDH/SDH tributary signal
OAM
East signal
ADM
Synchronous Multiplexing System
. Regenerator (REG)
REG is placed in the middle station of the network , which mainly used to amplify optical power so as to extend the optical transmission distance , but it can not add/drop service.
OAM
East signalWest signal
STM-NSTM-N
REG
Synchronous Multiplexing System
2 、 Characters
1 、 One step Multiplexing
Add/Drop tributary signal ( Drop 2M from 2.5G )。
2 、 Powerful Cross-connect Capacity
Realize:line to line, line to tributary and tributary to tributary cross-connection.
3 、 Powerful OAM Capacity
4 、 Flexible networking capacity
5 、 Powerful network survivability
Synchronous Multiplexing System
3 、 Cross performance indices
. Cross hierarchy
High order cross : VC-4 level cross connection.
Low order cross : VC-12 level cross connection 。 Which can guarantee to drop 2M service from high rate service directly 。
Synchronous Multiplexing System
、 Cross capacity
Cross capacity is generally written as n × n VC-4 。 For example:2.5G ADM provide powerful cross capacity 。 high order cross capacity : 96 × 96 VC-4.
Synchronous Multiplexing System
. Cross category
Provide the following categories at least :Uni-direction : The crossed port only be used as output 。Bi-direction : Every port can be used as both the input signal port and the output signal port 。Broadcast : Every input signal can connect with more ports。
Synchronous Multiplexing System
4 、 System Structure
Timing Communication Unit
OW
PDH & SDH tributary interface
LI LI
cross matrix
Synchronous Multiplexing System
4.1 、 Line interface
Line signal STM-N O-E conversion ; Process AU_PTR ; produce/end SOH 。
4.2 、 Cross matrix
Complete the cross-connection function of high –speed signals based on VC_4;
Add/Drop service to/from high speed signals.
Synchronous Multiplexing System
4.3 、 Tributary interface
Add/Drop service at the station 。 Service Categories:2M 、 34M 、 45M 、 140M 、 155M etc.
4.4 、 Timing unit
Inside : Provide timing signal to internal units
Outside : Tracing external timing signal ; Drop timing signal from Line/Tributary signal ; Holdover/oscillation 。
Synchronous Multiplexing System
4.5 、 Communication and control unit
Collect data from all units ; Present to NMS through DCC path , On the contrary, receive commands from NMS and implement them.
4.6 、 Order Wire unit
Provide order wire for contact 。
Synchronous Multiplexing System
SDH Self-healing Network
1.1 Self-healing Network
Self-healing network can automatically recover the carrie
d services from a failure fault in a very short period of time.
1.2 Types of self-healing network
1 Line protection switching(less than 50 ms)
2 Self-healing ring network
SDH Self-healing Network
1.3 Categories of self-healing ring network 1 Path protection switching ring
2 Multiplex segment protection switching ring
Unidirectional MSPS
Bi-directional MSPS
SDH self-healing network
SDH self-healing network
Line protection switching Self-healing ring network
Path protection switching ring
Multiplex segment protection switching ring
Unidirectional MSPS Bi-directional MSPS
Types of SDH self-healing network:
SDH self-healing network
Normal condition
1.4 Two-fiber Unidirectional Path Protection Ring
SDH Self-healing Network
Principle : send together and receive first
S:service optical ,P:protection optical 。Normal :From A to C :S : A --- B --- C , P : A --- D --- C 。 similar , From C to A : S : C --- D --- A ; P : C --- B --- A 。
SDH self-healing network
Fault condition
Two-fiber unidirectional path protection switching ring
SDH self-healing network
Fault :The cable between B and C is cut off
AC service : the signal come from A is lost ,So switching to the P optical fiber.
Receive signal via : A --- D --- C
CA service is in the original way.
SDH self-healing network
1.5 Two-fiber MS-Shared Protection Ring
Normal condition
SDH self-healing network
Normal :AC signals are transmitted along S1/P2 optical fiber in clock direction while CA signals along S2/P1 in anticlockwise direction.
From A to C :S : A --- B --- C
From C to A :S : C --- B --- A
P1 and P2 can transmitted additional service.
SDH self-healing network
Fault condition
SDH self-healing networkTwo-fiber MS-Shared Protection Ring
Fault:
The cable between B and C is cut off
AC service : the signal come from A is lost ,So switching to the P optical fiber.
Receive signal via : A --- D --- C
CA service is in the original way.
At B node: Switching to the anticlockwise direction : A---B--- A --- D --- C 。At C node : Switching to the clockwise direction : C --- D --- A 。
SDH self-healing network
Network Synchronization
1 、 Multiple Clock sources
. External clock source
. Drop clock source from STM-N interface
. Internal clock source
A). Holdover mode
Utilize pre-24hours memory information to stimulate synchronous status ; precision index : 0.37ppm 。B). oscillation
precision index : 4.6ppm 。
Network Synchronization
Network Synchronization1 Network synchronization
Network synchronization is one important part in the network. Which can ensure the transmitting end and the receiving end working in the synchronous status.
2 SSM function
SSM is transferred by the fifth to the eighth bits of S1 byte.
b1 b2 b3 b4 b5 b6 b7 b8
SSMThese four bits have 16 different kinds of codes
representing 16 different synchronization quality grades
Network Synchronization3 Selection of clock source
The NE first selects the clock of highest quality grade.
The NE selects the clock source which passes the least numbers of NE.
Thanks!
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