3 - intro sdh

8/8/2019 3 - Intro SDH

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ALCATEL University - - Ed1 -

Page 0.1

OVERVIEW OF THE SYNCHRONOUS DIGITALHIERARCHY

( SDH )

8/8/2019 3 - Intro SDH


ALCATEL University - - Ed1 - Page 0.2

OVERVIEW OF THE SYNCHRONOUS DIGITAL HIERARCHY

A BRIEF HISTORY

- 1983 : BELLCORE proposal and standardization of a 45 Mbit/s synchronous frame

(SYNTRAN system) providing direct access to the 64 kbit/s channel

- at the same time,AT&T develops a synchronous system (METROBUS) at 146 Mbit/s.

- 1985 : BELLCORE begins research into a "Synchronous Optical Network " project.

"SONET will be the basis of work at the CCITT.

- 1986 : CCITT committee set up on the subject.

- 1988 : first CCITT Recommendations are published (G.707 to G.709).

- 1990 : ETSI chooses multiplexing as the way forward.

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PDH VERSUS SDH

PDH SDH

PDifferent standards between US and rest of

world. No standard above 565 Mbit/sPWorldwide CCITT standard, three

standard rates:

155 Mbit/s, 622 Mbit/s, 2.5 Gbit/s, 10 Gbit/s

PManufacturer-specific administration PStandardization of TMN under way (info

model)

PAccess to basic channels at the cost of

numerous multiplexing/demultiplexing stagesPSimplified access to basic channels by the

system of A.U. and A.D.M. (Add and Drop

Multiplexors)

PService modification long and costly PReconfiguration on request by T.M.N.

PRuggedness and rerouting of data

expensivePNew network structures (loop) with

inherent protection

PKnowledge of quality in "portions" PKnowledge of quality from end to end


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8/8/2019 3 - Intro SDH



STM-N AU-4AUG VC-4

TUG-3

TUG-2

TU-12

TU-2

TU-3 VC-3

VC-2

VC-12

VC-11 C-11

C-12

C-4

AU-3 VC-3 C-3

TU-11

139.264 Mbit/s

44.736 Mbit/s

34.368 Mbit/s

C-2 6.312 Mbit/s

2.048 Mbit/s

1.544 Mbit/s

xN x1

x3

x7

x4

x7

x1

x1

x3

x3

STM-N FRAME MULTIPLEXING STRUCTURE

Multiplexing

Pointer processing

Alignment

Mapping


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STRUCTURE OF THE STM-1 FRAME

1

RSOH

PAYLOAD

MSOH

9

1 9 10 270

R OH: Regenerator ection Overhead

OH: ultiplex ection Overhead

Frame length: 2430 bytes

Frame frequency: 8 kHz

Bit rate: 155.520 bit/s


8/8/2019 3 - Intro SDH




A1 A1 A1 A2 A2 A2 J0

1 E1¡

1

D1 D2 D3

AU P¢

INTE£

S

2

2

2 K1 K2

D4 D5 D6

D7 D8 D9

D10 D11 D12

S1 Z1 Z1 Z2 Z2 M1 E2

YTES£

ESE£

VE D¡

¢

£

¡

UT U£

E INTE£

NATI ¢ NAL STANDA£

DIZATI ¢ N

YTES£

ESE£

VE D¡

¢

£

NATI¢

NAL USE

MEDIA DEPENDENT

YTES

A1,A2¡

raming

D 1, D12 D at a co mm un icat io n ch an nel

J0 (o r C1) M odule identi ¤ ier

E1,E2 ¢ rderwire¡

1 User channel

1

IP-8 (regenerator section quality)

2

IP-24 (multiplex section quality)

K1,K2 APS channel

Z1,Z2 Spare

S1 Synchronization state

M1 "¡

E

E section"

SOH STRUCTURE(ITU-T G.708)

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A1 A1 A1 A2 A2 A2 J0

¥

1 E1¦

1

D1 D2 D3

AU P§

INTE ̈

S

¥

2¥

2¥

2 K1 K2

D4 D5 D6

D7 D8 D9

D10 D11 D12

S1 Z1 Z1 Z2 Z2 M1 E2

¥

YTES ̈

ESE ̈

VED¦

§

̈

2 M¥

IT/S, JUSTI¦

IED

MEDIA DEPENDENT¥

YTES

A1,A2¦

raming

D 1, D1 2 D at a co mm unic at io n c ha nne ls

J0 ( or C1) M od ule id ent i©

ier

E1,E2 § rderwire¦

1 User channel¥

1¥

IP-8 (regenerator section quality)¥

2

¥

IP-24 (multiplex section quality)K1,K2 APS channel

Z1,Z2 Spare

S1 Synchronization state

M1 "¦

E¥

E section"

SOH STRUCTURE(ETSI proposal TM4, not ITU-T compliant)

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RADIO SYSTEM FRAME ( STM-1 )1

RSOH

PAYLOAD

MSOH

9

1 9 10 270

S : egenerator Section verheadMS : Multiplex Section verhead

Lenght rame: 2430 octets

rame requency: 8 K z

it rate: 155.520 Mbit/s

2Mbit/S Way Side Tra ic

Speci ic bytes or A96xxUSY(ATPC,MC,DSI)+ E1, 1,D1-D2-D3

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PR INCIPLES OF MULTIPLEXING IN SDH

- mapping of t e plesioc ronous tri utary into a container using padding and justification its: conventional

plesioc ronous multiple ing.

- addition of t e corresponding PO H (creation of t e virtual container )

- t e virtual container is t e asic element in SDH

- alignment of t e virtual containers in t e tri utary units y positive-zero-negative justification. The C floats

ithin the TU. Its position is indicated on each frame y pointers .

- identical alignment y pointers is used to form the AU.

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Terminology:

AU-n Administrative Unit,level n (= VC-n PT for high order containers

AUG Adminitrative Unit Group (group of AU-n)

C-n Container, level n

TU-n Tributary Unit, level n (=VC-n PT for basic containers)

TUG Tributary Unit Group (group of TU-n)

VC-n Virtual Container, level n (=C-n POH)

Bit rate (kbit/s) for networks in which the hierarchy is based on a

primary rate of

Digital hierarchy level G702 1544kbit/s 2048kbit/s

1 1544 20482 6312 8448

3 44736 34368

4 97728 139264

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PT

1

2

N

STM-N

PT

PT

P

P

VC-4VC-3ouVC-12

MULTIPLEXING ITH TWO LEVELS OF POINTERS

PT

PT: P INTE


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ALCATEL University - - Ed1 -Page 0.13


SPI R ST ST SA SPIR STST

SOME FUNCTIONAL BLOCKS FROM RECOMMENDATION G.782

SPI (Synchronous Physical Interface)

RST (Regenerator Section Termination): Starts and ends the RSOH

MST (Multiplex Section Termination): Starts and ends the MSOH

MSA (Multiplex Section Adaptation): AU3/4 pointer processing

SEMF MCF

SETS SETPI

Q interfaceF interface

external synchronization

SEMF (Synchronous Equipment Management Function): converts supervision data into object-oriented

messages

MCF (Message Communication Function): provides the means of conveying TMN messages

SETS (Synchronous Equipment Timing Source): represents the frequency standard for the network

element

SETPI (Synchronous Equipment Timing Physical Interface): physical interface with the external clock

3 - intro sdh

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