59223623 Synchronous Digital Hierarchy[2]

8/3/2019 59223623 Synchronous Digital Hierarchy[2]

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Synchronous Digital HierarchySynchronous Digital Hierarchy

Muhammad Zeeshan

Frame Structure, Overheads and Pointers


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SDH Overview

SDH Frame Structure

SDH Multiplexing

Overhead

Pointers


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SDH OVERVIEW


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SDH Definition

Synchronous Digital Hierarchy (SDH) is a standard

which is developed by the International

Telecommunication Union (ITU)

It is documented in standard G.707 and its extension G.708

It was developed to replace the Plesiochronous Digital

Hierarchy (PDH) system for transporting large amounts of

telephone and data traffic and to allow forinteroperability

between equipment from different vendors


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Limitation of PDH

INTERFACES:

Electrical interfaces

There are only regional standards, instead of universal standards

Optical interfaces

No unified standards for optical line equipments, manufacturers

develop equipment according to their own standards


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PDH: the electric interface is a standard interface, but the opticalinterface is not a standard interface

Special PDH optical signal

Manufacturer

A

Manufacturer

B

Standard electric interface

2Mbit/s or 34Mbit/s

PDH Network

Manufacturer

B

Standardization of optical interface


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Limitations of PDH

MULTIPLEXING METHOD:

Asynchronous Multiplexing

Code rate justification is required for matching and

accepting clock difference

The locations of the low-rate signals in high-rate signals

are not regular nor fixed


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European Series

565Mb/s565Mb/s

139Mb/s139Mb/s

34Mb/s34Mb/s

8Mb/s8Mb/s

2Mb/s2Mb/s

4

4

4

4

Japanese SeriesNorth American Series

1.6Gb/s1.6Gb/s

400Mb/s400Mb/s

100Mb/s100Mb/s

32Mb/s32Mb/s

6.3Mb/s6.3Mb/s

1.5Mb/s1.5Mb/s

274Mb/s274Mb/s

45Mb/s45Mb/s

6.3Mb/s6.3Mb/s

44

4

4

6

7

3

5

64Kb/s64Kb/s

24 30

3

3

Limitations of PDH


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Limitations of PDH

140/34 Mb/s 34/140Mb/s

34/8 Mb/s 8/34 Mb/s

8/2 Mb/s 2/8 Mb/s

2 Mb/s

Optical/Electrical Electrical/Optical

multiplexing

demultipexing

AddingandDroppingin PDH


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Limitations of PDH

OPERATION & MAINTENANCE (OAM)

PDH signal frame structure has very few overhead bytes

for Operation, Administration, and Maintenance (OAM)

NETWORK MANAGEMENT INTERFACE

No universal network management interface for PDH

network


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Advantages of SDH over PDH

INTERFACE

Electrical interfaces

SDH provides a set of standard rate levels----STM-N.

(N= 4n =1, 4, 16, 64).

The basic signal transmission structure level is STM-1, at a rate of

155Mb/s

Optical interfaces

Optical interfaces adopt universal standards. Line coding of SDH

signals involves scrambling, instead of inserting redundancy codes


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SDH Network

Standard optical interface

Uniform STM-N optical signal

Manufacturer

A

Manufacturer

B

Standardization of optical interface

SDH has standard optical interface


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MULTIPLEXING METHOD

Low-rate SDH signals high-rate SDH

Signals via byte interleaved multiplexing method

PDH signals SDH

Synchronous multiplexing method and flexible mapping structure


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STM-256

STM-64

STM-16

STM-4

STM-1

4

4

4

4

STM-1, 2, 34, 140 Mb/s

STM-N

N

SDH Multiplexing


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SDHSDH SignalsSignals BitBit rate(Mb/s)rate(Mb/s)

STMSTM--11 155155..520520 oror 155155MM

STMSTM--44 622622..080080 oror622622MM

STMSTM--1616 24882488..320320 oror22..55GG

STMSTM--6464 99539953..280280 oror 1010GG

SDH higher-rate signal (STM-4,16,64) is exactly 4 times that

of the lower-rate signal (STM-1)

STM: Synchronous Transport Module

SDH Signals and Data Rates


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ADM155Mbit/s

Optical interface

155Mbit/s

Optical interface

2Mbit/s

Electric signal

SDH: Economical and easy way for network!

Adding and dropping in SDH


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OPERATION & MAINTENANCE

Abundant overhead bits are used for OAM.

Unnecessary to add redundancy bits to monitor line

performance during line coding

COMPATIBILITY

SDH network and the existing PDH network can work

together

SDH network can accommodate the signals of other hierarchies

such as ATM, FDDI, and Ethernet


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SDH FRAME STRUCTURE


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STM-N Frame Structure

For the convenience of signal analysis, the frame

structures of the signals are often illustrated as block

frame structures

The frame structure of PDH signals, ATM signals and

data packets of IP network are also block frames

The frame of E1 signals is a block frame of 1 Rows x32 Columns consisting of 32 Bytes


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RSOHRSOH

MSOHMSOH

11

33

44

55

99

STMSTM--N payloadN payload

(including POH)(including POH)

99 261261

270 Columns270 Columns

9 Rows9 Rows

PP

OO

HH

AUAU--PTRPTR

RSOHRSOH:: RegeneratorRegenerator SectionSection OverheadOverhead

MSOHMSOH:: MultiplexMultiplex SectionSection OverheadOverhead

POHPOH:: PathPath OverheadOverhead

AUPTRAUPTR:: AdministrativeAdministrative UnitUnit PointerPointer

125125 ss

STM-1 Frame Structure


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RSOHRSOH

MSOHMSOH

11

33

44

55

99

STMSTM--N payloadN payload

(including POH)(including POH)

99NN 261261NN

270270NN

ColumnsColumns

9 Rows9 Rows

PP

OO

HH

AUAU--PTRPTR

RSOHRSOH:: RegeneratorRegenerator SectionSection OverheadOverhead

MSOHMSOH:: MultiplexMultiplex SectionSection OverheadOverhead

POHPOH:: PathPath OverheadOverhead

AUPTRAUPTR:: AdministrativeAdministrative UnitUnit PointerPointer

STM-N Frame Structure125125 ss


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SDH Frame Structure - ANATOMY

Transmission rate of single byte of STM-N frame:

STM-N frame contains 2430xN Bytes and each frame is

transmitted every 125 s

That means a given byte is transmitted 8000 times a second

Transmission rate of a single byte:

8000 x 8 = 64 Kbps

Transmission rate of a STM-1 frame:

9 rows x 270 columns x 8000 frames/s x 8 bits = 15,55,20,000 bps

= 155.52 Mbps


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11

21612161

270270

24302430

271271 540540

1st Byte of1st Byte of

STM frame # 1STM frame # 1Last byte ofLast byte of

STM frame # 1STM frame # 1

STMSTM--1 Frame # 11 Frame # 1 11stst ByteByte

STMSTM FrameFrame ## 22

Transmission Mode: ByteTransmission Mode: Byte--byby--Byte,Byte,From Left to right & top to bottomFrom Left to right & top to bottom

TransmissionTransmission DirectionDirection

1st1st

ByteByte

24302430thth

ByteByte

STM-1 Frame Transmission


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SDH Frame Structure

Payload

area for services transmission in STM-N

2M, 34M, and 140M signals are packed and carried

in the payload of STM-N frame over SDH network

Path Overhead (POH) after packing low rate

signals, POH is added for OAM of every frame


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SDH Frame Structure

Section Overhead (SOH)

monitors the whole STM-

N frame

Regenerator Section Overhead (RSOH) monitors the

whole STM-N frame.

Multiplex Section Overhead (MSOH) monitors each

STM-1 of the STM-N frame.

RSOH, MSOH, and POH compose the integratedmonitoring system of SDH.


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SDH Network NE Types

Terminal Multiplexer(TM)

Add/Drop Multiplexer(ADM)

Regenerator(REG)


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Regenerator

Regenerator has the job of regenerating the clock and amplitude

relationships of the incoming data signals that have attenuated

and distorted by dispersion

The regenerator replaces the RSOH bytes before re-transmitting

the signal

RegeneratorSTM-N STM-N


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Terminal Multiplexer

Terminal multiplexers are used to combine

plesiochronous and synchronous input signals into

higher bit rate STM-N signals

Terminal Multiplexer

PDH

SDH STM-N


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Add / Drop Multiplexer

PDH and SDH signals can be extracted from or

inserted into high speed SDH bit streams by means of

ADMs

Add / Drop Multiplexer

PDHSDH

STM-N

Towards other NEs

Customers

IPATM

STM-N

Towards other NEs


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Sections in the SDH Network

There are three sections in the SDHPath

Multiplex Section

Regenerator Section

The overheads are always generated at the beginning of a

section and only evaluated at the end of a section

Terminal

MultiplexerAdd/Drop

MultiplexerTerminal

MultiplexerREG REG REG

Path

Multiplex Section

Regenerator Section


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Payload

Path

Section

Optical

Payload

Path

Section

OpticalOptical FiberCable

RSOH

MSOH

POH

Overhead Layer


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How to understand SOH and POH?

Both SOH and POH are OAM bytes added to ensure correct andflexible transmission of signals

SOH and POH are used in different layers to supervise and

administrate the signals. RSOH and MSOH are used in RS and MS

separately, but HPOH and LPOH are used for VC-3/VC4 and VC12LPOH----used to supervise small package (VC-12)

HPOH----used to supervise big package (VC-3 / VC-4)

MSOH----used to supervise the carriage(STM-1) of the truck

RSOH----used to supervise the motorcade formed by trucks (STM-4/16/64)


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SDH Frame Structure

AU Pointer (AU-PTR)

Used for alignment of lower rate signals in the payload of STM-N

frame to accurately locate the payload

AU-PTR is added in transmitting end, when the signal is packed

into the payload of STM-N frame

At receiving end, the low rate signal is dropped from STM-N

frame according to the AU-PTR value

Low-rate signals in the STM frame are arranged obeying some

rules byte interleave; so only have to locate the first low-rate

signal in the STM frame


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SDH MULTIPLEXING


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SDH Multiplexing

SDH Multiplexing includes:Low to high rate SDH signals (STM-1 STM-N)

PDH to SDH signals (2M, 34M & 140M STM-N)

Other hierarchy signals to SDH Signals (ATM STM-N)


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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 1

3

1

7

3

139264 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

1

1

1

4

4

4


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Mapping, Aligning and Multiplexing

Low-rate tributaries are multiplexed into STM-N signals through three procedures:

Mapping

Aligning

Multiplexing.

MAPPING

SDH mapping is a procedure by which tributaries are adapted into virtual containers at the

boundary of an SDH network, for example, E1 into VC-12, E3 into VC-3, E4 into VC-4.

ALIGNING

SDH aligning is a procedure by which the frame-offset information is incorporated into the

tributary unit, by adding a pointer

The pointer value constantly locates the start point of the VC frame within the payload, so that

the receiving end can correctly separate the corresponding VCMULTIPLEXING

SDH multiplexing is the procedure by which multiple lower order path layer signals are adapted

into a higher order path


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Multiplexing Structure

C: Container

VC: Virtual Container

TU: Tributary Unit

TUG: Tributary Unit GroupAU: Administrative Unit

AUG: Administrative Unit Group


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Mb Signal Mapping Procedure

C12

RateAdaptation

2 Mbps Signal

1 4

1

9

125 s

1 Byte Path

Overhead

(POH)

1 4

1

9

VC12

C-12 Size: (9 Rows x 4 Columns) 2 = 34 Bytes

C12

POH

VC-12 Size: (9 Rows x 4 Columns) 1 = 35 Bytes

125 s

VC-12 = C-12 + (1 Byte POH)

C-12 Frame Duration = 125 s

VC-12 Frame Duration = 125 s

There can be four different POH

bytes for one C-12 V5, J2, N2, K4

MAPPING


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Multiplexingx 3

1 12

1

9

TUG2

T

U

-

12

125 s

1 4

1

9

VC12

C12

POH

125 s

1 Byte Tributary

Unit Pointer(TU-PTR)

1 4TU12

C12

POH

125 s

PTR

T

U

-

12

T

U

-

12

TUG-2 size: (9 Rows x 12 Columns) = 108 Bytes

TU-12 Size : (9 Rows x 12 Columns) = 36 Bytes

TU-12 = VC-12 + (1 Byte TU-PTR)

TUG-2 = TU-12 + TU-12 + TU-12

TU-12 and TUG-2 Frame Duration = 125 s

ALIGNING MULTIPLEXING


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RR


1 12

1

9

TUG2

T

U

-12

125 s

T

U

-12

T

U

-12

Multiplexing

x 71 86

1

9

TUG3

125 s

T

U

G

-

2

T

U

G

-

2

T

U

G

-

2

T

U

G

-

2

T

U

G

-

2

T

U

G

-

2

T

U

G

-

2

TUG-3 Size = (TUG-2) x 7 + R (2 Columns)

TUG-3 Frame Duration = 125 s


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1 86

1

9

TUG3

125 s

Multiplexing

x 3

R

P

O

H

1 261

1

9

VC4

125 s

T

U

G

-

3

T

U

G

-

3

T

U

G

-

3

R

VC-4 = TUG-3 + TUG-3 + TUG-3 + R (2 Columns) + POH (1 Column)

VC-4 Frame Size = 9 Rows x 261 Columns = 2349 Bytes



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VC4


1 2611

9

125 s

AU-PTR

AU4

VC4

1 2701

9

125 s

AUG1 270

1

9

125 s

STM-11 270

1

9

125 s

Multiplexing

x 1

RSOH and

MSOH

AU-PTR

VC4AU-PTR

VC4AU-PTR

MSOH

RSOH

2MbMultiplexingRoute

2 Mb C-12 VC-12 TU-12 TG-2 TG-3 VC-4 AU-4 AUG STM-1


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34 Mb Signal Mapping Procedure

C3

Rate

Adaptation

34 Mbps Signal

1 84

1

9125 s

Path

Overhead(POH)

C3

1 85

1

9125 s

P

O

H

VC3

C-3 Frame Size: 9 rows x 84 columns = 756 Bytes

C-3 Frame Duration: 125 s

VC-3 = C-3 + (POH) POH = 9 Rows x 1 Column = 9 Byte

VC-3 Frame Size: 9 Rows x 85 Columns = 765 Bytes

VC-3 Frame Duration: 125 s


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VC3

Tributary

Unit Pointer

1 86

1

9

125 s

Fixed

Stuffing Bits1 86

1

9

125 s

TU3

H1

H2

H3

R

TUG3TU3H1

H2

H3

TU-3 = VC-3 + TU-PTR TU-PTR = 3 Byte Pointer (H1, H2 and H3)

TUG-3 = TU-3 + R (Fixed StuffingBits)

R (Fixed Stuffing Bits) = 6 Bytes (Fixed Stuffing Bits)

TU-3 and TUG-3 Frame Duration = 125 s

STUFFING


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T

U

G

3

1 261

1

9

125 s

P

O

H

R R

VC4Multiplexing

x 3

TU3

1 86

1

9

125 s

H1

H2

H3

R

TUG3

VC-4 = TUG-3 + TUG-3 + TUG-3 + R (2 Columns) + POH (1 Column)

VC-4 Frame Size = 9 Rows x 261 Columns = 2349 Bytes


T

U

G

3

T

U

G

3


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VC4


1 2611

9

125 s

AU-PTR

AU4

VC

4

1 2701

9

125 s

AUG1 270

1

9

125 s

STM-11 270

1

9

125 s

Multiplexing

x 1

RSOH and

MSOH

AU-PTR

VC

4

AU-PTR

VC

4

AU-PTR

MSOH

RSOH

34MbMultiplexingRoute

34 Mb C-3 VC-3 TU-3 TUG-3 VC-4 AU-4 AUG STM-1


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VC-4 = C-4 + (POH) POH = 9 Rows x 1 Column = 9 Byte

VC-4 Frame Size: 9 Rows x 261 Columns = 2349 Bytes


C4

Rate

Adaptation

140 Mbps Signal

1 260

1

9

125 s

C-4 Frame Size: 9 rows x 260 columns = 2340 Bytes

C-4 Frame Duration: 125 s

Path

Overhead(POH)

C4

1 261

1

9

125 s

P

O

H

VC4

Rate Adaptation: The process of Bit stuffing, to account for different

clock rates of the signals coming from different sources


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VC4

AU-PTR

10 270

1

9

125 s

Multiplexing x 1

AU-PTR

AU-PTR: A 9 byte pointer is inserted at Row No 4

AU4 Size: (1x9)+(9x261) = 2358 Bytes

1 9

A U 4

10 270

1

9

125 s

1 9

AU4 AUG4

In case of 140 Mb signal mapping in STM-1, AU-4 and AUG are identical

AU-4 and AUG Frame Duration: 125 s

4


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STM-1

RSOH and

MSOH

1 270

1

9

125 s

A U 4

10 2701

9

125 s

1 9

RSOH

MSOH

AUG4

RSOH Size: 3 Rows x 9 Columns = 27 Bytes

MSOH Size: 5 Rows x 9 Columns = 45 Bytes

STM-1 Size: 9 Rows x 270 Columns = 2430 Bytes

STM-1 Frame Size: 125 s

3

5

A U 4

270

125 s

1AUG4


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OVERHEADS


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Overhead Bytes

270

1

9

STM-1 FrameStructure

RSOH

MSOH

AU-PTR PO

H

OVER

HEAD

1

PAYLOAD


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Section Overhead (SOH)

Overhead in SDH frame structure are classified as:

Section Overhead SOH

Path Overhead POH

SOH is further divided into RSOH and MSOH

RSOH can be accessed in the regenerator or at the terminal

equipment

MSOH can be processed at the terminal equipment


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Regenerator Section Overhead RSOH

A1 A1 A1 A2 A2 A2 J0 X X

B1 E1 F1 X X

D1 D2 D3

: Media dependent bytes

X: Bytes reserved for national use


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A1 and A2 Bytes

Frame Alignment (Framing) Bytes

Indicate the beginning of the STM-N frame

A1 = F6H (11110110), A2=28H (00101000)

In STM-N: (3XN) A1 bytes, (3XN) A2 bytes

stream

STM-N STM-N STM-N STM-N STM-N STM-N

Finding frame head

Frame # 1 Frame # 2 Frame # 3 Frame # 4 Frame # 5 Frame # 6


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A1 and A2 Bytes

Framing

Next

process

Find

A1,A2

OOF

LOF

N

Y

AIS

over 3ms

625 s

OOF: Out Of Frame

LOF: Loss Of Frame

AIS: Alarm Indication Signal


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Regenerator Section Trace J0 Byte

Regenerator Section Trace Byte: J0

Its used to transmit repetitively a Section Access Point

Identifier so that a section receiver can verify its continued

connection to the intended transmitterAnother usage of the J0 byte is that J0 byte in each STM-N

frame is defined as an STM identifier C1 i.e., to identify

individual STM-1 inside a multiplexed STM-N

Within the domain of a single operator, this byte may use

any character


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B1 Byte

Tx

2#STM-N

Rx

1#STM-N

Calculate

B1 of STM-N #1

1#STM-N

2#STM-N

Verify B1 B2

STM-NA1 00110011

A2 11001100

A3 10101010

A4 00001111

B 01011010

BIP-8

Bit interleaved ParityC

ode (BIP-8) ByteA parity code (even parity), used to check the transmission

errors over the RS

Place the result

of BIP in B1 of

STM-N #2


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F1 Byte

User Channel Byte: F1

Provides a 64 kb/s data/voice channel for special

maintenance purposes.

F1

TM REG TMADM


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E1 and E2 Bytes

Digital telephone channel

E1-RS, E2-MS

E1 and E2

TM ADM TMREG

Orderwire Bytes: Provides one 64 kbps each for voicecommunication

E1: RS Orderwire Byte RSOH orderwire messageE2: MS Orderwire Byte MSOH orderwire message


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Quiz

If only E2 byte is used as order wire byte, then order

wire voice communication is provided between:

A and B

B and C

C and D


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Quiz

If only E1 byte is used as order wire byte, then order

wire voice communication is provided between:

A and B

B and C

C and D

A and D


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D1 ~ D12 Bytes

TMN

DCC channel

NE NE NENE

OAM Information: Control, Maintenance,

Remote Provisioning, Monitoring (Alarm &

Performance), Administration

Data Communications Channels (DCC) BytesMessage-based Channel for OAM between NEs and NMS

RS-DCC D1 ~ D3 192 kbit/s (3X64 kbit/s)

MS-DCC D4 ~ D12 576 kbit/s (9X64kbit/s)


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Multiplex Section Overhead MSOH

B2 B2 B2 K1 K2

D4 D5 D6

D7 D8 D9

D10 D11 D12

S1 M1 E2X X

X: Bytes reserved for national use


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B2 Bytes

The B1 byte monitors the transmission error of the

complete STM-N frame signal

The B2 bytes monitor the error performance status foreach STM-1 frame within the STM-N frame

There are N*3 B2 bytes in an STM-N frame with

every three B2 bytes corresponding to an STM-1 frame

B2 B t


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B2 Bytes

B2 Byte Principle

At transmitting end, the BIP-Nx24 is computed over all bits of the STM-N frame except for the first three rows of SOH, and the result is placedin 3 bytes B2 of the preceding frame before scrambling.

At receiving end, the BIP- Nx24 is computed over all bits of the frameexcept for the first three rows of SOH, and then Exclusive OR with theB2 bytes of the later arrived frame.

If the value of Exclusive OR operation is zero, there is no bit block error.Any mismatch in result indicates transmission errors.

For example

BIP-N24 is computed over

a frame of signal composed

of 9 bytes.

11001100 11001100 11001100

01011101 01011101 01011101

11110000 11110000 11110000BIP24

01100001 01100001 01100001

K1 d K2 (b1 b5)


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K1 and K2 (b1 ~ b5)

Automatic Protection Switching (APS) channelbytes

Used for transmitting APS signaling to implement

equipment self-healing function

The K1 byte and K2(b1~b5) are used forautomatic switchover to a standby path

K1 d K2 (b1 b5)


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K1 and K2 (b1 ~ b5)

NE-A NE-BWorking path

Standby path

Working path

Standby path

NE-B detects a transmission error on the line and informs NE-A via K1 byte

to switchoverNE-A switches to the standby channel

NE-A via K2 byte indicates the switchover in NE-B

NE-B switches to the standby channel

K1

K2

S1 Byte


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S1 Byte

bits 5 ~ 8 Meaning

0000 Quality unknown (existing sync. Network)Quality unknown (existing sync. Network)

0010 G.811 PRCG.811 PRC

0100 G.812 transitG.812 transit

1000 G.812 localG.812 local

1011G.813 SETS (Synchronous EquipmentG.813 SETS (Synchronous Equipment

Timing Clock)Timing Clock)

1111 Do not use for sync.Do not use for sync.

Synchronization Status Message Byte (SSMB)Synchronization Status Message Byte (SSMB)

This byte is used forThis byte is used forsynchronizationsynchronization of networkof network

Bits 5 to 8 of S1 byte indicate theBits 5 to 8 of S1 byte indicate the qualityoftheincomingclockqualityoftheincomingclockThe smaller the value of S1 (b5The smaller the value of S1 (b5--b8), the higher the level of clock qualityb8), the higher the level of clock quality

This helps to determine whether or not to switch the clock source, i.e.This helps to determine whether or not to switch the clock source, i.e.

switch to higherquality clock sourceswitch to higherquality clock source

M1 B t


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M1 Byte

Tx Rx

Traffic

Multiplex Section Remote Error IndicationMS-REIByteThis byte is used to report back the number of error blocks

detected by the receiver by evaluating three B2 bytesTx generate corresponding performance event MS-REI

B2 B2 B2

Report no. of

errors detected

Evaluate B2 and

detect bit errors

M1

Generate MS-REIMS-REI


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Path Overheads

J1

B3

C2

G1F2

H4

F3

K3

N1

12

3

45

6

7

89

VC-n Path Trace Byte

Path BIP-8

Path Signal Label

Path StatusPath UserChannel

TU Multiframe Indicatio

Path UserChannel

AP Switching

Network Operator

Higher Order Path OverheadHigher Order Path Overhead

1 2 3 4 5 6 7 8 9 10

h l b l


72/85

72

Path Signal Label : C2 Byte

C2 byte is used to indicate the type and composition

of the VC-4 tributary information

h S G


73/85

73

Path Status : G1 Byte

Path status byte

This byte is used to report back the fault from path sink to path

source and is set in the POH of the opposite direction

HP-REI HP-RDI Reserved

87654321

HP-REI: High order Path Remote Error Indication

HP-RDI: High order Path Remote Defect Indication

HP REI d HP RDI


74/85

74

HP-REI and HP-RDI

Higher order Path Remote Error IndicationThe SDH NE (sink end) checks B3 bytes

If error blocks are detected, the number oferror blocks detected

is sent to the remote terminal in HP-REI signal

The SDH NE (sink end) checks J1 and C2 bytes

Higher order Path Remote Defect Indication

If J1 and C2 fail to be consistent, HP-TIM (Higher order path

Trace Identifier Mismatch) and HP-SLM (Higher order PathSignal Label Mismatch) alarms are generated

HP-RDI is sent back to the remote end

M l if I di i H4 B


75/85

75

Multiframe Indication : H4 Byte

This byte indicates the frame

label for a multiframe in the next

VC-4 payload

The value of this byte ranges

from 00H to 03H

P th O h d


76/85

Path Overheads

V5 J2 N2 K4

VC-12 VC-12 VC-12 VC-12

1

9

1 4

500s VC

-12 multiframe

Low Order Path OverheadLow Order Path Overhead

Path Status and Signal Label : V5 Byte


77/85

77

Path Status and Signal Label : V5 Byte

BIP-2

Parity code of VC-12

LP-REI

Low order Path Remote Error Indication

LP-REI is set to "1" and returned to teh opposite direction if one or more errors are detected via BIP-2

LP-RFI

Low order Path Remote Failure Indication

If a defect condition persists beyond the maximum allowed time, it becomes a failure, then LP-RFI is set to "1"

and sent back to the source

Signal Label

Indicates type and composition of VC-12 tributary information

LP-RFI

Low order Path Remote Defect Indication

If sink end detects a TU-12 AIS, it sets LP-RDI to "1" and sends back to the source

BIP-2 LP-REI LP-RFI Signal Label LP-RDI

87654321


78/85

POINTERS

P i t


79/85

Pointers

Pointers

AU-PTR TU-PTR

AU PTR


80/85

AU-PTR

RSOHRSOH

AUAU--PTR

PTR

MSOHMSOH

44

11

99

AU PTR


81/85

81

AU-PTR

Y: Fixed value 1001SS11

F: Fixed value 11111111

H3: Additional transmission capacity during negative

justification

H1 and H2: Pointer value is contained in the last ten bits of H1

and H2

H1 Y Y H2 F F H3 H3 H3

87654321 9

AU PTR


82/85

82

AU-PTR

N: New data flag bits

A notification to the receiver about the change in pointer value and pointer

justification operation

AU/TU type:

For AU-4 and TU-3, SS=10

I/D: Increment/Decrement bitsD bits are inverted to decrement next AU-PTR address (-ve justification)

I bits are inverted to increment next AU-PTR address (+ve justification)

N N N N S S I D I D I D I D I D

H1 and H2

TU PTR


83/85

83

TU-PTR

The tributary unit pointer is used to indicate the

specific location of the first byte (V5) of the VC-12

within the TU-12 payload

TU-PTR


84/85

TU PTR

VC-12 VC-12 VC-12 VC-12

V1 V2 V3 V4

1

9

500s VC-12 multiframe

TU POINTERSTU POINTERS


85/85

THA

NK YOU

Date post:	06-Apr-2018
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59223623 Synchronous Digital Hierarchy[2]

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