The Synchronous Digital Hierarchy (SDH) (Vol.1)

SAR ISC S&T100 TELE 0005

ITU-T Recommendations

– G.707 Bitrates

– G.708 Signal Structure (NNI)

– G.709 Synchronous Multiplex Structure

– G.703 Electrical characteristic

– G.957 Optical interface characteristic

SDH Multiplexing Components

• Containers – C

• Path Overheads -POH

• Virtual Containers – VC

• Pointers

• Tributary Units – TU

• Tributary Unit Groups – TUG

• Administrative Units – AU

• Administrative Unit Groups – AUG

• Multiplexer Section Overhead – MSOH

• Regenerator Section Overhead - RSOH

SDH BIT RATES

• Synchronous Transport Modules (STM)

• STM-1: 155.520 Mbit/s

• STM-4: 622.080 Mbit/s

• STM-16: 2,488.320 Mbit/s

• STM-64: 9,953.280 Mbit/s

• STM-256: 39.81312 Gbits/s

Multiplexing PDH to SDH

E1, T1, E3, T2,T3, E4 can be directly

multiplexed/ de multiplexed to/from any

higher order bit rates.

STM 1

• 63x E1 or

• 3x E3 or 3x T3

• 84x T1 or

• 1x E4 or

• 21x T2 or

combinations

SDH EQUIPMENTS

Terminal Mux –TM

Add Drop Mux – ADM

Regenerators

Digital Cross Connects DX

SDH PATHS

• End to end of a Bandwidth( Circuits)

• Goes through different Network Elements

• Lower order Path

• Higher Order Path

SDH SECTIONS

Regenerator Section

Multiplex Section

Multiplex and Regenerator Sections

Multiplexing of E1

• E1=2.048 Mbps(+ 50 ppm)

• 32x8bit in 125 micro sec

• 32x1Bytes in 125 micro sec

• 32 Bytes in 125 micro sec

Multiplexing of E1

• Container for Multiplexing E1 = C12

• C12 = 34 Bytes/ 125 micro sec

• 16 bits of Stuffing

Virtual Container 12 (VC12)

• =C12+ 1 Byte(LPOH)

• Using 1 Byte LPOH, 4 different Bytes are send in 500 Micro sec Multi frame

• LPOH Bytes are V5, J2, N2 and K4

Mapping of 2Mbps into STM – N

LPOH

LPOH…

LPOH…

Tributary Unit 12 (TU12)

• TU12= VC12+ 1Byte TU Pointer• Pointer points the position of V5 Byte(Start of VC12)• Pointers mapped in 500 micro sec multi frame• Pointer Bytes are V1, V2, V3 and V4.• V1 and V2 used for Pointers• TU12= 36 Byte/125 micro sec• 9x4 matrix, each cell 1 byte=64kbps• TU12 is denoted as “M” in bandwidth configurations

Mapping of 2Mbps into STM – N

Mapping VC12 into TU12

TU Pointer

TU12 Multi frame

TU12 Multi frame

TU12 Multi frame

Tributary Unit Group 2 (TUG2)

• Multiplexing 3 x TU12

• Byte interleaved

• 108 Bytes/125 micro sec

• 9x12 Matrix, each cell 1 byte=64kbps

• TUG2 is denoted as “L”

• Each “L” contains 3 “M”

Mapping of 2Mbps into STM – N

Mapping TU12’s into TUG2’s

SDH Multiplexing Structure

Tributary Unit Group 3 (TUG3)

• Multiplexing 7 x TUG2 + 18 Stuffing Bytes

• Byte interleaved.

• 774 Bytes / 125 micro sec

• 9 x 86 Matrix, each cell 1 byte=64kbps

• TUG3 is denoted as “K”

• Each “K” Contains 7 “L”

Mapping of 2Mbps into STM – N

Virtual Container 4 (VC4)

• Multiplexing 3 x TUG3 + 18 stuffing Bytes + 9 Bytes Higher Order Path Overhead(HPOH)

• 2349 Bytes/ 125 micro sec

• 9x261 Matrix, each cell 1 byte=64kbps

VC4 Frame structure

VC4 Path Over Head (HPOH)

HPOH….

HPOH…

HPOH…

Administrative Unit 4 (AU4)

• VC4 + 9Byte AU Pointer

• AU pointer points the Start Position of VC4 in the Frame (i.e. Position of J1 Byte in the frame)

• AU4= 2358 Bytes/ 125 micro sec

• AU4 is denoted as “J”

• Each “J” contains 3 “K”

Administrative Unit 4 (AU4)

AU-Pointer

Administrative Unit Group (AUG)

• AUG1 Contains 1 AU4, 1x J Leads STM1

• AUG4 Contains 4 x AUG1’s, 4x J Leads STM4

• AUG16 Contains 4 x AUG4’s,16 x J Leads STM16

• AUG64 Contains 4 x AUG16’s, 64 x J Leads STM64

Synchronous Transport Module1

• AUG1+ 45 Bytes MSOH + 27 Bytes RSOH

• 2430 Bytes/ 125 micro sec

• 155.52 Mbps

• 9x270 Matrix

SDH Multiplexing Structure

SDH Multiplexing Structure…

STM1 Section Overheads

Mapping E3/T3(DS3)

SDH ALARMS

What Next?

• Protection• Bandwidth Configuration-Provisioning• Structure of SDH Equipments