SDH Theory

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ISO 9001:2008

What is SDH?

SDH = Synchronous Digital Hierarchy It is a transport network

synchronous fully standardized with high bandwidth for synchronous and asynchronous signals

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ISO 9001:2008

for future broadband signals and new services with standardized network management capabilities with traffic protection with a flexible multiplexing structure

direct access to tributaries cross-connections without de-multiplexing

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ISO 9001:2008

Digital Transmission System

Regenerator recreates the signal.

Multiplexer (MUX) Multiplexer combines data from

several lines and transmits itover a higher-capacity data link.

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No signal

60 km

R

60 km

Regenerator

MUX MUX

ISO 9001:2008

Multiplexer Naming Conventions

Terminal Multiplexer (TM) All traffic is terminated here. m: aggregate level n: lowest tributary level

Add-Drop Multiplexer (ADM) Part of the traffic is terminated. Part of the traffic goes transparently

through.5

TMm/n

aggregate

tribu taries

ADM

m/n

aggregateaggregate

tributaries

ISO 9001:2008

Digital Cross-connect (DXC m/n)

No traffic is terminated. Cross-connection matrix

connects tributary signals of one aggregate to another aggregate.

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PDHMUX

PDHMUX

PDHMUX

PDHMUX

DDF

SDHCross-Connect

ISO 9001:2008

PDH Bit Rates & HIERARCHY

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E1

E0

E2

E3

E4plesiochronous

plesiochronous

plesiochronous

synchronous

ISO 9001:2008

SDH Bit Rates & HIERARCHY

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STM1

STM4

STM16

STM64

ISO 9001:2008

PDH vs. SDH — Add & Drop Function

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ADM STM-1STM-1

Six TMs needed to drop E1

One ADM is enough to drop E1.

TM TM

TMTM

TMTM

E3

E3

E3

E2

E2

E1

E1

E1

E4 E4

E1 (2.048 kbit/s)

E2

2/1 2/1

3/23/2

4/3 4/3

PDH

SDH

ISO 9001:2008

STM-1 Frame

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2430 bytes/frame × 8 bit/byte × 8000 frame/s = 155.52 Mbit/s

transmitted from top to bottom and left to right

ISO 9001:2008

SDH Multiplexing Structure (ETSI)

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Pointer processing

Multiplexing

Aligning

Mapping

VC-4STM-N

× N

× 3× 1

× 3

× 7

139 264 kbit/s

44 736 kbit/s34 368 kbit/s

6312 kbit/s

2048 kbit/s

1544 kbit/s

AUG AU-4

TUG-3

TUG-2

TU-3

TU-2

TU-12

VC-2

VC-3

VC-12

VC-11

C-4

C-3

C-2

C-12

C-11

× 1

C-n Container-n

× 1

C Container

VC Virtual Container

TU Tributary Unit

TUG Tributary Unit Group

AU Administrator Unit

AUG Administrator Unit Group

ISO 9001:2008

PDH over SDH Container (C)

basic payload unit

Virtual Container (VC) C + POH (path overhead)

Tributary Unit (TU) VC + pointer The pointer indicates the

start of the VC and allows dynamic alignment of the VC within the TU frame.

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2 Mbit/s plesiochronous stream

Justification bytes

C12

Path OverheadVC12

Container

POH

TU PointerTU12

Virtual Container

ISO 9001:2008

KLM Coordinates

A U -4 po in te rs

M S O H

P ayloadV C -4 (H O -V C )

R S O H

VC-4 POH

VC-12

VC-12

K

L

TU12-1 TU12-2 TU12-3

TUG3-1 TUG3-2 TUG3-3

TUG2-6

TUG2-7

TUG2-5

TUG2-4

TUG2-3

TUG2-1

TUG2-2

TUG-3 number (values 1-3)TUG-2 number (values 1-7)TU-12 number (values 1-3)

KLM: 271KLM: 152 KLM: 300

VC-3

ISO 9001:2008

Termination of Sections

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Path

Multiplexing Sections Multiplexing Sections

Regenerator Sections

TM TM

ISO 9001:2008

Regenerator

Regenerates the optical signal.

Terminates RSOH.

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REG

STM-N STM-N

ISO 9001:2008

Terminal Multiplexer

Terminates RSOH and MSOH.

May terminate HOP and LOP overhead.

Multiplexes/maps tributary signals.

Includes timing and management functions.16

TMSTM-N

orPDH

STM-M

ISO 9001:2008

Add/drop Multiplexer

Terminates RSOH and MSOH. May terminate HOP and LOP overhead. Includes connection function between the two aggregates. Multiplexes/maps tributary signals. Includes a connection function for allocation of TUs within the STM frame. Includes timing and management functions.

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STM-N or PDH

STM-MSTM-M

ADM

ISO 9001:2008

Cross-connect

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• Terminates RSOH and MSOH.

• Includes connection function between the aggregates.

• Can have tributary ports, for which it may terminate HOP and LOP overhead.

• Includes timing and management functions.

STM-N or PDH

STM-MSTM-M DXC

ISO 9001:2008

SDH Overhead Overheads carry information for monitoring, maintaining

and controlling the operation of network. Overhead types

POH for end-to-end monitoring of payload signal (VC-12, VC-3 and VC-4) Block errors, far end alarms, trace and payload type

SOH is used for monitoring of signal between SDH equipment. RSOH: block errors, trace MSOH: block errors, synchronization, and far-end alarms

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POH

RSOH

MSOH

POINTER

9 260

270

3

5

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ISO 9001:2008

RSOH

A1, A2 framing patterns (F6H), (28H) J0 regenerator section Trail Trace Identifier (TTI) B1 BIP-8 parity byte E1 RS orderwire channel (service telephone) F1 user (network operator) data channel D1, D2, D3 regenerator section Data Communication Channel

(DCCR) NU1, NU2, NU3, NU4 bytes reserved for national use R1, R2, R3, R4, R5, R6 media specific bytes (e.g. radio link) U1, U2, U3, U4 bytes with no defined use

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ISO 9001:2008

MSOH

B2 BIP-24 parity bytes K1, K2 Automatic Protection Switching (APS) channel, D4 to D12 multiplex section Data Communication Channel (DCCM) S1 synchronization status M1 Remote Error Indication (REI) E2 MS orderwire channel (service telephone) NU5, NU6 bytes reserved for national use U5 to U26 bytes with no defined use Z12, Z13, Z21, Z22 bytes with no defined use

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ISO 9001:2008

Functions of POH (Path Overhead)* Parity check (B3, V5/BIP-2 calculated by terminating point)

* Alarm and performance information (V5, G1)

* Structure of VC (Signal label C2)

* Multi-frame indication for TUs (H4)

* User communication channel-between path elements (F2, F3)• Identification of path source (path trace J1, J2)

Functions and characteristics of the individual elements

1) The Administrative Unit (AU)

* Is shaped if a pointer is allocated to the VC formed at last

* Clock justification through positive –zero-negative stuffing in the AU pointer area

* Byte by byte stuffing

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ISO 9001:2008

2) The container (C)

* Basic packaging unit for tributary signals (PDH)

* Synchronous to STM-1

* Bit rate adaptation is done via a positive stuffing procedure

* Adaptation of synchronous tributaries by fixed stuffing bits

* Bit by bit stuffing

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ISO 9001:2008

3) The virtual container (VC)

* Formation of the container by adding of POH (Path Overhead)

* Transport as a unit through the network (SDH)

* A VC containing several VCs has also same pointer area

4) The Tributary Unit (TU)

* Is formed by adding pointer to

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5) Tributary Unit Group (TUG) * Combines several TUs for new VC

ISO 9001:2008

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ISO 9001:2008

Any Questions?

ISO 9001:2008

THANK YOU