SDH Overhead Bytes

SDH Overhead BytesSDH Overhead Bytes

SDH Overhead BytesSDH Overhead BytesSDH Overhead BytesSDH Overhead Bytes

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

J1

B3

C2

G1

SDH Frame: Overhead Bytes

SDH Overhead BytesSDH Overhead BytesSDH Overhead BytesSDH Overhead Bytes2. 45

H1 H2 H3

B2 K1 K2

G1

F2

H4

F3

K3

N1

D4

D7

D10

S1

D5

Z1 Z2

D8

D11

D6

D9

D12

M1 E2

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

J1

B3

C2

G1

Regenerator Section Overhead Bytes


H1 H2 H3

B2 K1 K2

G1

F2

H4

F3

K3

N1

D4

D7

D10

S1

D5

Z1 Z2

D8

D11

D6

D9

D12

M1 E2

� Provide a frame (F) alignment pattern

� A1 = 11110110 A2 = 00101000

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4

F3

D4

D7

D5

D8

D6

D9

A1, A2 Framing


� Provided for each STM-1 signal within an STM-n

K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

� Transmits a fixed pattern

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4

F3

D4

D7

D5

D8

D6

D9

J0 Regenerator Section Trace


� Transmits a fixed pattern repetitively

� Used by the section receiver to verify its continued connection to the intended transmitter

K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

� The Trace (pattern) is an assigned string (either 16 or 64 bytes in length) with an included ending CRC byte

� The Trace is sent a byte per frame� Both ends of a link set their own unique

transmit values and compare the received

J0 Regenerator Section Trace


transmit values and compare the received values with the expected

NE A NE B NE C

Send : “…NE A send”Expect : “Expect NE B…”

Send : “Expect NE B…”Expect : “…NE A send”

Send : “…NE B send”Expect : “Expecting NE C…”

Send : “Expecting NE C…”Expect : “…NE B send”Receive : “ …different message…”

?��

� �

� Provides an 8-bit wide bit-interleaved even parity check for error performancemonitoring at the regenerator section level

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4

F3

K3

D4

D7

D10

D5

D8

D11

D6

D9

D12

B1 8-bit Parity Check


� The parity check is computedfor all bytes of the previousSTM-N frame after scrambling

� The computed value is placed in this byte beforescrambling

� Provided for the first STM-1 signal within an STM-N

K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

Byte # Tx Value Rx Value7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0

1 01010110 010101102 10110110(…Noise…) 111111113 10101010 101010104 … …

… … …2429 11001101 11001101

B1 8-bit Parity Checking


2429 11001101 110011012430 01100110 01100110

–––––––– ––––––––BIP(e) 11100001 Mismatch 10101000

–––––––– ––––––––Changes across one byte can always be detectedDouble bit changes (2 “0”s going to 2 “1”s) down a bit column cannot always be detectedNoise corruptions would affect several/many bytes

� Provide a local orderwirechannel for voicecommunication

� E1 is part of the RSOHand may be accessed at regenerators

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4

F3

K3

D4

D7

D10

D5

D8

D11

D6

D9

D12

E1, E2 Orderwire Channels


at regenerators

� E2 is part of the MSOH and may be accessed at Multiplex Section terminations


K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

� Allocated for user’spurposes

� Terminated at allregenerator section-level equipment

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4

F3

D4

D7

D5

D8

D6

D9

F1 User Channel


� Provided for the firstSTM-1 signal within an STM-N

K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

D1-D3, D4-D12 Datacom Channel (DCC)

K2

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1

J1

B3

C2

G1

F2

H4

F3

K3

D4

D7

D10

D5

D8

D11

D6

D9

D12

� Provide a message-based data communicationschannel, includingadministration,monitor, alarm andmaintenance functions


K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

maintenance functions

� D1-D3 define a 192 Kbps channel in the RSOH

� D4-D12 define a 576 Kbps channel in the MSOH


A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

J1

B3

C2

G1

AU Pointer Bytes


H1 H2 H3

B2 K1 K2

G1

F2

H4

F3

K3

N1

D4

D7

D10

S1

D5

Z1 Z2

D8

D11

D6

D9

D12

M1 E2

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4

F3

D4

D7

D5

D8

D6

D9

H1-H3 AU Pointers

� Provide indications andflags regarding the frame contents

� Define the start position of the VC-4 within the STM-1 frame


K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

STM-1 frame

� Provide a method for letting the VC-4“float” within the AU-4 frame

� Provide an indication of AU-4 concatenation

H1-H3 Contents

� In the STM-0 frame (a single VC-3) the relevant overhead bytes total 3 bytes

H3H2H1

S S I D I D I D I D IN N NN D

1 2 3 4 5 6 7 8 9 10111213141516

Justification


� In the STM-1 frame (a VC-4 (i.e. three VC-3 frames), the same information bits are spread over 9 bytes with the infill bits preset

H3 H3 H3H2 H2 H2H1 H1 H11 2 3 4 5 6 7 8

JustificationX XNNNN

1 2 3 4 5 6 7 8

0 0 1 1 11

1 2 3 4 5 6 7 8

0 0 1S S S S 1 11

1 2 3 4 5 6 7 8

1 1 1 1 1

1 2 3 4 5 6 7 8

1 1 1 1 1 1 1 1

1 2 3 4 5 6 7 8

1I D I D I D I D I D 1 1

10-bit pointer value

H3H2H1

N N N S S I D I D I D I D IN D1 2 3 4 5 6 7 8 9 10111213141516

Negative justification opportunity

H1-H3 Contents


I = Increment Negative justification :D = Decrement Invert 5 D-bits, accept majority voteN = New data flag (from 0110 to 1001)

Positive justification :Pointer value (b7-b16) : Invert 5 I-bits, accept majority voteNormal range is 0-782 (for AU-4)

SS bits = 10 / AU-4,AU-3 structure

H3H2H1

F F F F

Pointer Bytes

Frame “N” Frame “N+1”

Link Between Section Overhead and VC


Pointer Bytes

Section OverheadFrame “N”

Pointer Bytes

Section OverheadFrame “N+1”

Virtual

Container

J1

AU-4 Pointer Adjustment: Positive Justification

H1 H2 H3

H1 H2 H3

1) Indicating the mismatch

2) Changingthe I/D flag 1


H1 H2 H3

H1 H2 H3

the I/D flag

3) Pushing theVC-4 for 3 bytes span

4) Pointing to the new pointer value

1

2+3

4

AU-4 Pointer Adjustment: Negative Justification

H1 H2 H3

H1 H2 H3

1) Indicating the mismatch

2) Changingthe I/D flag

1


H1 H2 H3

H1 H23) Pulling the VC-4 for 3 bytes span

2+3

44) Pointing to the new pointer value

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

J1

B3

C2

G1

Multiplexer Section Overhead Bytes


H1 H2 H3

B2 K1 K2

G1

F2

H4

F3

K3

N1

D4

D7

D10

S1

D5

Z1 Z2

D8

D11

D6

D9

D12

M1 E2

� Include a 24-bit wide bit-interleaved even paritycheck, for errorperformance monitoringat the multiplexer

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4

F3

K3

D4

D7

D10

D5

D8

D11

D6

D9

D12



at the multiplexersection level

� The check is computed for all bytes of the previous STM-N frame, except those located in the RSOH

� Provided for each STM-1 signal within an STM-N

K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

B2 24-bit Parity Checking

Byte #7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0

1 01010110 11001101 010101104 10110110 10011001 111111117 10101010 01100110 10101010

10 … …… … …

2398 11001101 11100111 11001101


2398 11001101 11100111 110011012401 01100110 00110010 01100110

–––––––– –––––––– ––––––––BIP-24 (e) 11100001 11100111 10101000

–––––––– –––––––– ––––––––

Changes affecting adjacent across several bytes are more likely to be detected. Double bit changes (2 “0”s going to 2 “1”s) down a bit column cannot always be detected Noise corruptions would affect several/many bytes

� Provides MPS signalingbetween multiplexersection terminatingequipment

� Provided for the first

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4

F3

D4

D7

D5

D8

D6

D9

K1 Multiplexer Protection Switching (MPS)


� Provided for the firstSTM-1 signal within an STM-N

K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

� Used to return an indicationto the transmit end that thereceived end has detectedan incoming section defect

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4D4 D5 D6

K2 Remote Defect Indication (RDI)


an incoming section defector is receiving AIS


H4

F3

K3

N1

D4

D7

D10

S1

D5

Z1 Z2

D8

D11

D6

D9

D12

M1 E2

� Indicates the type of clocksource used to time thetransmitted signal

� The indications are one ofthe four synchronization

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4

F3

D4

D7

D5

D8

D6

D9

S1 Quality of Synchronization


the four synchronizationlevels agreed to by theITU-T, or that the source should not be used

K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

Code

0010

0100

Synchronization level

1 x 10-11 PRC (primary reference clock)

5 x 10-9 SSU-T (synch. source unit - transit)

Stratum

1

2

S1 Contents


1000

1011

1111

1 x 10-7 SSU-L (synch. source unit - local)

4.6 x 10-6 SEC (SDH equipment clock)

DNU (do not use)

3

4

� Used to send errorperformance informationfrom multiplexer sectionreceiving equipment to

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

J1

B3

C2

G1

F2

H4

F3

K3

D4

D7

D10

D5

D8

D11

D6

D9

D12

M1 Remote Error Indication (REI)


receiving equipment tothe originating equipment

� Conveys the count of interleaved bit blocks detected in error by the B2 byte

K3

N1

D10

S1 Z1 Z2

D11 D12

M1 E2

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

J1

B3

C2

G1

Path Overhead Bytes


H1 H2 H3

B2 K1 K2

G1

F2

H4

F3

K3

N1

D4

D7

D10

S1

D5

Z1 Z2

D8

D11

D6

D9

D12

M1 E2

� Provides a unique messageset up for each path in theSDH network

� Supports continuity testingbetween any location on atransmission path and the

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

D4

D7

D5

D8

D6

D9

J1

B3

C2

G1

F2

H4

F3

J1 Path Trace


transmission path and thepath source location

� Provided for each VC-4 frame in the frame

D10

S1 Z1 Z2

D11 D12

M1 E2

K3

N1

� Includes an 8-bit widebit-interleaved paritycheck that provideserror performancemonitoring at the

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

D4

D7

D10

D5

D8

D11

D6

D9

D12

J1

B3

C2

G1

F2

H4

F3

K3



monitoring at theVC-4 level

� The parity check is computed for all bytes of the previous VC-4 before scrambling

� The computed value is placed in this byte before scrambling

D10

S1 Z1 Z2

D11 D12

M1 E2

K3

N1

� Provides an indication ofthe payload constructionby means of a value labelassigned from a list of 11possibilities

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

D4

D7

D5

D8

D6

D9

J1

B3

C2

G1

F2

H4

F3

C2 Signal Label


possibilities

� Indicates what type of payloads are mapped within the virtual container

D10

S1 Z1 Z2

D11 D12

M1 E2

K3

N1

C2 Content

Standard binary values for C2 are :� 0000 0000 Unequipped� 0000 0001 Equipped, non-specific� 0000 0010 TUG structure� 0000 0011 Locked TU-n� 0000 0100 34 Mbps or 45 Mbps into C-3

asynchronous


asynchronous� 0001 0010 140 Mbps into C-4 asynchronous� 0001 0011 ATM mapping� 0001 0100 MAN (DQDB) mapping� 0001 0101 FDDI mapping� 1111 1110 Test signal, O.181 specific mapping� 1111 1111 VC-AIS

� Sends status and per-formance monitoringinformation from thereceiving terminatingequipment to the

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

D4

D7

D5

D8

D6

D9

J1

B3

C2

G1

F2

H4

F3

G1 Path Status


equipment to theoriginating equipment

� Bits 1-4 convey the count of errors detected by B3

� Bit 5 indicates a path Remote Defect Indication (RDI)

D10

S1 Z1 Z2

D11 D12

M1 E2

K3

N1

� Allocated for networkoperator communicationbetween path terminations

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

D4

D7

D5

D8

D6

D9

J1

B3

C2

G1

F2

H4

F3

F2, F3 User Channel


D10

S1 Z1 Z2

D11 D12

M1 E2

K3

N1

� Identifies which frame ofthe multi-frame is presentin the current VC-4

� (The TU overhead is

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

D4

D7

D5

D8

D6

D9

J1

B3

C2

G1

F2

H4

F3

H4 Multi-frame


� (The TU overhead isdistributed over four TUframes comprising theTU multi-frame)

D10

S1 Z1 Z2

D11 D12

M1 E2

K3

N1

VC-3 / VC-4Payload

V4

H4 (00)

H4 (01) VC-3 / VC-4Payload

V1

V2

TU-1/2 Multiframe Indication: Example Using H 4

Example of TU-1/2 Multiframe Indication

Using H4 Byte



V2


V3


V4

� Used to provide path-level protection switching on individual VC-4 paths

A1 A1 A1 A2 A2 A2 J0

F1B1 E1

J1

B3

K3 Automatic Protection Switch (APS)


D3D1 D2

H1 H2 H3

B2 K1 K2

D4

D7

D10

S1

D5

Z1 Z2

D8

D11

D6

D9

D12

M1 E2

C2

G1

F2

H4

F3

K3

N1

� Supports end-to-endperformance monitoringof a tandem connection(path sub-section)Communicates the

A1 A1 A1 A2 A2 A2 J0

F1

D3

B1

D1

E1

D2

H1 H2 H3

B2 K1 K2

D4

D7

D5

D8

D6

D9

J1

B3

C2

G1

F2

H4

F3

N1 Tandem Connection (TC) Monitor


� Communicates thenumber of B3 errors

� Bits 1-4 serve as incoming error count; Bit 5 serves as a TC-REI Bit 6 serves as an outgoing error indication Bits 7-8 serve as a multiframe (TC-APID, TC-RDI, ODI, reserved)

D10

S1 Z1 Z2

D11 D12

M1 E2

K3

N1

V5

N2

J2

V1

V3

V2 125 µs

250 µs

TU-1/2 Pointers and VC -1/2 Path Overhead


K4

N2

V4

V3 250 µs

375 µs

500 µs

V5

N2

J2

� Bits 1-2 are used for a Bit InterleavedParity (BIP) check on the previousVC-2/VC-1

� Bit 3 is a path Remote Error Indicator(REI)

V5 Error Checking, Signal Label, Path Status


K4

N2(REI)� Bit 4 is a path Remote Failure Indicator

(RFI)� Bits 5-7 provide a VC-2/VC-1 signal

label� Bit 8 is a path Remote Defect Indicator (RDI)

1 2 3 4 5 6 7 8

BIP-2BIP-2 REIREI RFIRFI RDIRDISignalSignal

V5 Detail

V5 functions :

Signal Labels :0 0 0 Unequipped or supervisory-unequipped0 0 1 Equipped – non-specific0 1 0 Asynchronous


0 1 0 Asynchronous0 1 1 Bit synchronous1 0 0 Byte synchronous1 0 1 Reserved for future use1 1 0 Test signal, O.181 specific mapping1 1 1 VC-AIS

V5

J2

� Used to transmit repetitively a Low Order Path Access Point Identifier, so that a path receiving terminal can verify its continued connection to the intended transmitter

� Used in the same way as J0 in the SOH

J2 Path Trace


K4

N2� Used in the same way as J0 in the SOH

� Bits 1-2 are used as an even BIP-2 check for the Tandem Connection

� Bit 4 operates as an incoming AISindicator

V5

J2

N2 Tandem Connection ( TC)


� Bit 5 indicates errored blocks within the TC

� Bit 6 indicates errored blocks of the ingressing VC-n

� Bits 7-8 operate in multi-frame as an access point identifier and as defect indicators

K4

N2

V5

� Bits 1-4 are allocated for APS signaling for protection at the lower order path level

K4 Automatic Protection Switching (APS)


K4

N2

J2

STM-1 : 270 columns x 9 rows

AU-3/AU-4 Pointer

MSOH

RSOH

* TUG-3 : 86 columnsTUG-3 POINTERNPI

FIXED

J1VC-4 : 261 columns

Fixed

STUFF

TU-3.Ptr

POH

TU-3.Ptr

VC-3 POH

*TU-3 : 86 columns

C3=34/45 Mbit/s

X3*

SDH Basics


TU-2 Ptr.

*TUG-2 :12 columns

FIXEDSTUFF

VC-12POH

TU-12Ptr.

TU-12 : 4 columns

TU-2.Ptr

C2=6 Mbit/s

VC-2POH

X7*

TU- 2 : 12 columns*

Pointer resolutionFixed positionByte interleave*

HPX

AU-4

Synchronous

port

STM-1

Plesinchronous port

VC-4 C-4140

Mbps

ETSI SDH Multiplexing Scheme


Assembler

TUG-3

TUG-2

VC-4 VC-3

VC-12

C-3

C-12

34Mbps

2Mbps

LPX

TU-3

TU-2

TU-12

SDH Overhead Bytes

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