SDH Technology Overview

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SDH TechnologyUTSI-ENG-200114480100

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Outline

Basic Terms

Basic Concept

Multiplexing Structure

Network Topologies

Network Management

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Commonly Used Terms

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Lowest Operating Digital Rate Analog Signal converted to 64 Kbps

Data Stream 8 Bits = 1 Byte 8000 Bytes/Sec = 64000 bps

From Analog to Digital 8000 samples per second 8000 * 8 = 64000 bps

DS0 (Single Channel) Signal

Commonly Used Terms

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24 DS0 Multiplexed to 1 DS1

64 Kbps * 24 = 1536000 bps

+ 1 F bit * 8000 bps for Framing

= 1,544,000 bps or 1.5 Mbps

Commonly called a T1 Line (or C11 Container)

Commonly Used Terms

DS1 Signal

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32 DS0 Multiplexed to 1 E-1

64 Kbps * 32 = 2048 Kbps or 2.048 Mbps

Commonly called a E1 Line (or C12 Container)

Commonly Used Terms

E-1 Signal

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Commonly Used Terms

16 E-1 Multiplexed to 1 E-3

2.048 Mbps * 16 + 1.60 = 34.368 Mbps

Overhead

Commonly called a E3 Line (or C3 Container)

E-3 Signal

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Commonly Used Terms

4 E-3 Multiplexed to 1 E-4

34.363 Mbps * 4 + 1.812 = 139.264 Mbps

Overhead

Commonly called a E4 Line (or C4 Container)

E-4 Signal

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SDH Concept

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What is SDH ?

SDH - Synchronous Digital Hierarchy

A Modular, Layered & Organized Architecture using Synchronous Multiplexing Technique.

A Standardized hierarchical Set of Digital Transport Structures for transport of suitably Adapted Payloads

A Set of Improved & Standardized Management Interfaces and Functions, allowing Digital Transmission Systems to inter-work in a multi-vendor environment.

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What is SDH ?

An Evolutionary Step in Transmission Technology, enabling Network Operators to compete more successfully in the face of deregulation

A Vision of Transport Networks in Year-2000

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SDH Functional Layers

Circuit Layer Network

Path Layer Network

Transmission Media Layer Network

Circuit Layer

Lower Order Path Layer

Higher Order PathLayer

Multiplex Section Layer

Regenerator SectionLayer

Physical Medium Layer

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Circuit Layers

64 Kbps layer Network ISDN Services Network Mgmt & Control links

Leased Lines E1 / E2 / E3 / E4 Lines

B-ISDN / Virtual Circuit layer Network Variable bit rate & integrated broadband

Services

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Path Layers

VC-11 layer Network 64 Kbps links & 1.5 Mbps leased lines

VC-12 layer Network 64 Kbps & 2 Mbps leased lines

VC-3 layer Network LAN links, DS3 / E-3 leased lines

VC-4 layer Network VC-12, VC-3, B-ISDN / Virtual path & HDTV links

B-ISDN / Virtual path Network B-ISDN services, Virtual path link, Mgmt &

Control links

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Transmission Media Layers

Multiplex Section layer Network

VC-4 / VC-3 links, Mgmt & Control links

Regenerator Section layer Network

Multiplex Section links, Mgmt & Control links

Optical Section layer Network

Regenerator Section links

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SDH Network - A Layered Model

Circuit Layer Network

Multiplex Section Layer

Regenerator Section Layer

Physical Medium Layer

VC-11

VC-3

VC-12 VC-2 VC-3

VC-4

Circuit Layer

Path Layer

TransmissionMedia Layer

Section Layer

Higher OrderPath Layer

Lower OrderPath Layer

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SDH Equipment Layers

SDH Multiplexer SDH Multiplexer

PDHATM

IP

PDH

ATMIP

PA

TH M

ST

RST

PH

OTO

NIC

L

AYE

R

PA

TH

MST

RST

PH

OTO

NIC

L

AYE

R

SDHREG

Regenerator SectionRegenerator Section

Multiplex Section

Path

SDH Network

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SDH Multiplexing Structure

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SDH Signal Hierarchy

9.95328Gbps

2.48832Gbps

622.08Mbps 155.52

Mbps

STM-64 STM-16 STM-4 STM-1

(1)

(2)

(3)

(4)

[4]

[4]

[4]

(number) = Hierarchical Level[number] = Multiplexing

Factor

(Basic Signal)

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SDH Transport Rates

Signal Level

STM-1

STM-4

STM-16

STM-64

Rate (Mbps)

155.52

622.08

2488.32

9953.28

Capacity Voices

63 E13 E31 E4

252 E112 E3 4 E4

1008 E148 E316 E4

4032 E1192 E364 E4

189014401920

756057607680

302402304030720

12096092160122880

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SDH Multiplexing Structure

× 1

× 3

× 3

× 1

× 1

× 3

× 4

× 7

STM-N VC-4

VC-3C-3

C-2

C-12

VC-2

VC-11

TUG-2

139 264 kbit/s

44 736 kbit/s34 368 kbit/s

6312 kbit/s

2048 kbit/s

Pointer processing

Multiplexing

Aligning

Mapping

1544 kbit/sC-11

C-4

VC-12

AU-4

AU-3

AUG

TUG-3

TU-12

TU-11

TU-2

VC-3TU-3

× 7

x N

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Basic Frame Structure

Section Overhead (SOH)

Regenrator Section Overhead (RSOH)

Multiplex Section Overhead (MSOH)

Administrative Unit Pointer(s)

Information Payload

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SDH Frame Structure

1

3

4

9

Regenerator Section

Overhead(RSOH)

AU Pointer(s)

MultiplexSection Overhead

(MSOH)

STM-N Payload

270 x N Columns (bytes)

9 x N 261 x N

9 R

ow

s

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STM-1 Frame Structure

Synchronous Transport Module Level 1

9 Rows by 270 Columns

125 Micro Seconds Frame Length

8000 Frames per Second

Bit Rate 9 * 270 * 8000 * 8 = 155520000 Bits per Second

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STM-1 Frame Structure

Transport Overhead 9 Columns * 9 Rows 9 Columns * 3 Rows = 27 bytes for RSOH 9 Columns * 1 Row = 9 bytes for AU pointer(s) 9 Columns * 5 Rows = 45 bytes for MSOH

Synchronous Payload Envelope (SPE) 2349 (9 * 261) bytes 150.336 Mbps Enough Capacity to carry a E-4 payload (139.264

Mbps)

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STM-1 Frame Structure

1

3

4

9

Regenerator Section

Overhead(RSOH)

AU Pointer(s)

MultiplexSection Overhead

(MSOH)

STM-1 Payload

270 Columns (bytes)

9 261

9 R

ow

s

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STM-1 Section Overhead (SOH)

A1 A2A1 A1 A2 A2 J0 X X

B1

D1

E1

D2

X XF1

D3

Administrative Unit Pointer(s)

B2 B2 B2 K1 K2

S1 E2M1

D4

D7

D10

D5

D8

D11

D6

D9

D12

X X

9 R

ow

s9 bytes

RSOH

MSOH

X Bytes reserved for National Use

Media Dependent Bytes

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STM-1 SOH Functions

SOH Bytes

A1, A2

B1, B2

D1…D3

Functions

D4…D12

E1, E2

F1

J0

K1, K2

S1

M1

Frame Alignment

Performance Monitoring, Parity Bytes

Network Management, RS-DCC

Network Management, MS-DCC

Voice Communication, Voice Orderwire Chls

Maintenance, Voice/Data Channel

Section Trace Identifier

Automatic Protection Switching (APS) Control

Clock Quality Indicator (Synchronization Status)

Transmission Error Acknowledgement

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Path Overhead (POH)

Container POH Virtual Container

+

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Path Overhead (POH)

End-To-End Path Connectivity

Container Type Information

Quality Monitoring

Maintenance

Automatic Protection Switching

Tandem Connection Monitoring

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VC-3/4 POH

POH Bytes

J1

B3

C2

Functions

G1

F2

H4

F3

K3

N1

Path Indication

Performance Monitoring, Parity Bytes

Container Format

Transmission Error Acknowledgement

Superframe Indication

Automatic Protection Switching (APS) Control

Tandem Connection Monitoring

Maintenance

Maintenance

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VC-11/12 POH

POH Bytes

V5

J2

N2

Functions

K4

Error Indication & Monitoring

Automatic Protection Switching (APS) Control

Path Indication

Tandem Connection Monitoring

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C-4 Mapping into STM-1

Plesiochronous Signal(139.264 Mbps)

C-4Path Overhead

(POH)

C-4 POH

VC-4AU-4PTR

AUG (= AU-4) SOH

AU-4 Pointer

Section Overhead

(SOH)

Container

Virtual Container

Administrative Unit

STM-1

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Mapping of C-3 into STM-1

1

3

4

9

Regenerator Section

Overhead(RSOH)

AU Pointer

MultiplexSection Overhead

(MSOH)

STM-1 Payload

9 261

84

H1 H1 H1H2H3

H2H3

H2H3

Fixed S

tuff

Fixed S

tuff

J1B3C2G1

H4F3K3N1

F2

J1B3C2G1

H4F3K3N1

F2

J1B3C2G1

H4F3K3N1

F2

J1B3C2G1

H4F3K3N1

F2C-3

34 Mbps

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SDH Network Topologies

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SDH Network Elements

Regenerator (REG): used to extend the fiber reach

Terminal Multiplexer (TM): used in point-to-point network or at the end point of an Add/drop network

Add/Drop Multiplexer (ADM): used in Ring or Linear Add/drop network

Digital Cross-Connect (DXC or DCS): typically used in Mesh network to cross connect payload signals

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SDH Network Topologies

Point-to-Point Configuration

Linear Add/Drop (or Chain) Configuration

Ring Configuration

Star Configuration

Mesh Configuration

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Point-to-Point Configuration

A Simple Topology terminating SDH payload at each point of a Fiber Span

Requires Single SDH Multiplexer (Terminal MUX) on a Single Route

Typically, deployed in Transport Applications Enhanced Survivability with a Protection Path

SDH NE SDH NESTM-1 (OC-3)

Central Office

User Site

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Linear Add/Drop Configuration

SDH NESTM-1 (OC-3)

SDH NE

Central Office

SDH NE

User Site 1 User Site 2

STM-1 (OC-3)

Drop/Insert of relevant Traffic at Intermediate Sites

Used where Protection against Failure is not of great concern

Also, called Drop/Insert or Chain Configuration

Typically, deployed in both Regional Transit & Access Sub-

networks

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Ring Configuration

SDH NESTM-1 Ring

SDH NE

SDH NE

Site A

Site B

SDH NE

Working Path

Protection Path

Site D

Site C

Closed Loop Configuration with Add/Drop Multiplexers

Protection against: Fiber cut Signal failure/degrade (e.g., aging Laser) Node failure

Common Ring Topologies UPSR (Unidirectional Path Switched Ring) BLSR (Bi-directional Line Switched Ring)

DPR (Dedicated Protection Ring)

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UPSR Vs BLSR

All High Speed Line Resources are Service (Active/Standby) & Assigned on a round the Ring basis

A Dedicated Standby Path for each Active Path

Redundant End-to-End Paths

Head-end bridged & Tail-end Switched

Non-Revertive Path Switching (common)

Half High Speed Line Resources are Service & Half are Protection & assigned on a Span-by-Span basis

Different Paths depending on fault location

Single End-to-End Paths

Loop back to Protection

Revertive Line Switching

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Unidirectional Path Switched Ring

SDH NE

SDH NE

SDH NE

Site A

Site B

SDH NE

Site D

Site C

2 Fiber UPSR

Traffic from A to B to C

Traffic from C to D to A

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Bi-directional Line Switched Ring

SDH NE

SDH NE

SDH NE

Site A

Site B

SDH NE

Site D

Site C

2 Fiber BLSR

Traffic from A to B to C

Traffic from C to B to A

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Dedicated Protection Ring (DPR)

Unidirectional Line Switched Ring

Working Traffic & Protection Traffic in Opposite Directions

High Speed Line Resources assigned on a round the Ring Basis

A Dedicated standby Ring for an Active Ring

Revertive Line Switching

SDH NE2 Fiber DPR

SDH NE

SDH NE

Site A

Site B

SDH NE

Working Ring

Protection Ring

Site D

Site C

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Star Configuration

SDH NE

SDH NE

SDH NE

Central Office

User Site 1

User Site 2

SDH NE

User Site 2

(HUB NE)

Point-to-Point Connectivity on different routes from a Centralized Site

Terminating SDH Payload at each point of a Fiber Span

Centralized Site operates with HUB Configuration

Typically, deployed in both Regional Transit & Access Sub-networks

Enhanced Survivability with Protection Path on each route

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Mesh Configuration

S D H N E

S D H N E

S D H N E

S D H N E

Provides Capacity Sharing, Protection against Fiber Cut & Equipment Failures

Efficient use of Bandwidth & Traffic Restoration

Additional Protection using Spare Capacity

Suitable for Higher transmission networks

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SDH Network Management

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SDH Network Management

Configuration Management (CM)

Fault Management (FM)

Performance Management (PM)

Security Management (SM)

DCN Management

Management Functional Areas

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Configuration Management (CM)

Equipment Configuration

Termination Point (Physical Interfaces) Provisioning

Cross-Connect (or Payload Map)

Protection switching

Synchronization Configuration (Timing Synchronization)

NE Recovery

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Fault Management (FM)

Alarm Surveillance Alarm Detection Alarm Filtering Alarm Reporting

Fault Localization & Testing Fault Isolation Fault (or Alarm) Correlation Diagnostics (Loopbacks, Self-Diagnostics, etc.)

Alarm History Management

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Performance Management (PM)

PM Data Collection

PM Attributes Setting Thresholds Setting PM Evaluation Criteria Start Time, etc.

PM Data Reporting

Performance Monitoring History 24-hour Registers 15-minute Registers

Performance monitoring during Unavailable Time

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Security Management (SM)

User Access Control to protect Network against Unauthorized Access

Major Functions

Logon/Logoff

User Categories

Addition/Deletion of a User

Logs of Invalid login tries, Configuration related commands, etc.

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DCN Management

Configure & Control Resources in SDH NEs (e.g., DCC Management) Enable/Disable DCC (or ECC) Operational Status of DCC Network Parameters (Qos, Packet size, etc.)

Management of Network Addresses

Establish of Message Routing between DCC Nodes

Network Route Configuration Routing Tables Route Priorities