SDH~Different Overview

© Trend Communications

The Synchronous Digital Hierarchy (SDH) - II part -

by JM Caballero

Section

Transportation of a 2 Mbit/s circuit

SDH 2Mbit/s2Mbit/s

PBXPBXA B

C

D

Transportation of a 2 Mbit/s circuit 3/55© Trend Communications

Mapping of the 2 Mbit/s circuit

Mapping for the insertion (transmission) of the 2 Mbit/s circuit. At the ind of the path, for extracting the circuit (reception) the process is the inverse.

AU-4AUG C-4

TU-3 VC-3

C-3

C-2VC-2TU-2

C-12VC-12TU-12

C-11VC-11TU-11

TUG-3

AU-3

STM-1

ATM:2144kbit/sE1:2048kbit/s

x1

x3

x4

x7x7

x1

x1

TUG-2

x1

x3

STM-0

x3

STM-16

STM-4

x4

x16

x64

622 Mbit/s

2,5 Gbit/s

155 Mbit/s

51 Mbit/s(ANSI)

(ANSI)

(ANSI)

(ANSI)

x1VC-4

VC-3


Asynchronous mapping into a C-12 container (i)

The public network can be a RDSI circuit, Frame Relay, ATM, leased...

•• mapping of the 2 Mbit/s signal into the C2 container witch is synchronous with the network

•• The mapping is performed in four blocks of the same multicontainer of 500 µs

•• justification bits are added

2Mbit/s

VC-12

Public Network(1)

(2)

(3)

(4) (5)

136 bytes

500 µs

S

RS

RS

S

(32 x 8 bits)

I

(32 x 8 bits)

I

(32 x 8 bits)

I

(31 x 8 bits)

I

(1) S S S S S S S S

(2) C1C

2OOOOSS

(4) C1C

2S S S S S J

1

(5) J2 I I I I I I I

(3) C1C

2O O O O S S

: In format ion b i ts o f the 2 Mbi t /s c i rcu i t

: B i ts wi th ext ra in format ion

: stuffing bits

: by tes w i th in fo rmat ion b i t s and

ext ra in format ion

R

R

S: Stuff ingCi: Justif ication criteriaO : Ove rheadJ1: Posit ive just i f icat ionJ2: Negative just i f icat ion

S

I

125µs

C-12

500 µµs


Synchronous mapping in a C-12 container (ii)

This mapping maintains the byte synchronism of the 2 Mbit/s circuit and makes the connection of nx64k data/voice services easier because all 30 channels are directly located

•• the container is sinchronous with the 2 Mbit/s signal

•• The signal is framed in a 125 µs frame

•• There isn’t justification for adjusting clock drifts because is synchronous

1 2 5 ms

F i x e d m o d e34 b y t e s

R

(32 bytes)

I

10RRRRRR

2Mbit/s

C-12

VC-12

C A S C C S

1 to 15

Channe l s 16 to 30

Channe l s

Channels 16

1 to 15

Channe l s 17 to 31

TS0

TS16

Channe l s

32 bytes31 bytes

TS0

clientnetwork


Creation of the VC12 virtual container (iii)

The path overhead (POH) is added to the multiframe resulting the VC-12

VC-12

140 bytes

VC-12

500 µs

125 µ s

v5

500 µs

R

32 bytesI

R

32 bytesI

R

32 bytes

I

31 bytesI

R

35 bytes

35 bytes

35 bytes

35 bytes

J2

N2

K4

: V5 J2 N2 K4

POH (Path Overhead )

.

2Mbit/s

C-12

TU-12

client network

500 µµs

125 µµs


Aligning and multiplexing (iv)

•• The TU have a pointer (V5) in a fixed location witch identifies the carried information (the VC12)

•• The pointer points to the LO-POH overhead

•• A VC12 is a 4 element multiframe and need four TU14 frames for being transported

H4 = XXXXXX00

H4 = XXXXXX01

H4 = XXXXXX10

H4 = XXXXXX11

v1TU-12 1

35 bytes

PTR4

9

1v2

v3

v4

35 bytes

PTR: V1, V2, V3 ó V4

35 bytes

35 bytes

35 bytes

V1: 1st pointer byte V2: 2nd pointer byteV3: 3rd pointer byte V4: reserved

125 µµs

VC-12

TU-12

TUG-2

500 µµs

x3

125 µµs


Multiplexing and creation of TUG2 (v)

•• Three TU-12 are multiplexed in a byte oriented way in a new structure

•• The pointers are always in the firsts locations

•• The result is a Group of TU-12 known as TUG-2

P T RA

P T RB

P T RC

1

9

1 4

1

9

1 4

1

9

1 4

P T RA

P T RB

P T RC

1

9

1 12

TU-12 #1 TU-12 #2 TU-12 #3

35 by te s 35 by te s 35 by te s

T U G - 2 TUG-3

TU-12

TUG-2

x3

9 bytes of tu

-12#1

9 bytes of tu-12

#1

9 bytes of tu

-12#1

9 bytes of tu-12

#1

125 µµs


A new multiplexing forms a TUG3 (vi)

•• Seven TUG-12 are multiplexed in a byte oriented way and they form a new structure named TUG-3

•• Size 7x12=84 columns, plus 2 stuffing columns gives 86 columns

•• The pointers that identifies the information are always in fixed positions

x7

x3

TUG-2

TUG-3

VC-4

TUG-2 #1 TUG-2 #7

862

1

9

N

I

P

1

S

T U G -3

S

3

1

9

1

9

1 121 12

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

125 µµs


Creation of the VC-4 virtual container (vi)

•• A new multiplexing of three TUG-3 is executed to create a VC-4

•• Size 3x86=258 columns, plus 2 stuffing columns gives 260 columns

•• Then the POH overhead and the stuffing S bytes are added and the VC-4 is completed

x3

TUG-3

VC-4

AU-4

J 1

B 3

C 2

G 1

H 4

27011 12

F 2

9

13 14

S S

F 3

K 3

N 1

V C 4 - P O H

TUG-3 #2 TUG-3 #3

1

9

1

9

1

9

1 86 1 86 1 86

TUG-3 #1

10


Creation of the STM-1 frame (vii)

•• A AU4 pointer that points to the first byte of the VC-4 is included

•• The AU4 is in a fixed position of the frame. This fact allows its location

•• This operation is known as alingment

VC-4

AU-4

STM-1POH

J1

B3

C2G1

H4

F3

K3

N1

RSOH

MSOH

1 2709 10

27010 11VC-4

F2

STM-1


A VC12 multiframe request four STM-1 frames

A VC12 formed by four need a time interval of 500µs in order to put all four components into

12

VC -12

VC -12

VC -12

VC -12

V 1

V 2

V 3

V 4

5 0 0 ms

H 4 = 0 0

H 4 = 0 1

H 4 = 1 0

H 4 = 1 1

TUG-3TUG-3TUG-3

9

S T M -1

1 2 5 ms

S T M -1S T M -1500ms

S T M -1

9

J 1

B 3

C 2

G 1

H 4

F 3

K 3

N 1

F 2 RR

1

9

V C -4H 4

1

9 9

TUG-2

1

PTR1

TUG-2TUG-2

x3

x7

x3

Section

Overheads

A U P o i n t e r

B 2 B 2 B 2 K 1 K 2

S 1

D 4

D 7

D10

D 5

D 8

D11

D 6

D 9

D12

M 1 E 2

*A 1*

B 1

D 1

A 1*

A 1*

A 2 A 2* *

E 1

D 2

A 2J 0C 1

**

F 1

D 3

*


SDH Overheads

Each overhead is intended to do specific task related with the transmission management at different layers: regeneration, multiplexing and path

As the classical protocol tower an overhead is controlled just by one layer but is transparent for the rest of the SDH layers

M S O H

R S O HR S O H R S O H

Assembling ofVC-3 , VC-4

N N I N N I


C-11, C-12

C-3, C-4MUX

STM-N

Assembling of VC-3 , VC-4


C-11, C-12

C-3, C-4MUXSTM-N

S T M - N S O H

VC-3 , VC -4 POH

VC -11 , VC -12 POH

Add Drop Mult ip lexer

··

·

Add Drop Mult ip lexer


Path overheads

Each container (C-n) has associated an overhead, named Path Overhead (POH) with information enough to manage the transmission through the SDH network.

The union of C-n and POH is renamed as Virtual Container (VC-n) and is the interchange unit between origin and destination multiplexers.

LTMUX LTMUX

back up link

140 Mbit/s140 Mbit/s

active link

C4POH

+

VC4

PLL

POH

high order path

STM-1

RSOH

MSOH

Payload

POH

C4

STM-1

pointer


Higher order path overhead (HO-POH)

J1B3C2G1F2H4F3K3N1

Path trace, message of 16 or 64 bytes with CRC7> alarm HP-TIM High Order Path Trace Identifier Mismatch

BIP8 parity control > HO-EBER (Excessive Bit Error Rate) or SD (Signal Degraded) error

Path label > HP_SLM (Signal Label Mismatch) error

Path status (far signaling, alarm return or far error indication)

Path channel (64 kbit/s for voice or data)

TU12 multiframe indicator

Path channel (64 kbit/s for voice or data)

APS path protection > Mismatch K3 alarm

FEBE (Far End Block Errors) > HO-FEBE or HP-REI (Remote Error Indicator) error or LP-REI if it is a VC3

REI (FEBE)RFI

FERF UnusedG1:

Byte for tandem connection monitoring purposes

If 0<FEBE<9 shows the remote BIP-8 violation count as a binary number

FERF (Far End Reveive Failure) > HO/HP FERF o HP-RDI (Remote Defect Indication) alarm shows a remote AIS alarmdetected, or a LP-REI if it is a VC3

RFI/RDI (Remote Failure Indication) > RFI alarm indication

C2: 00 unequiped > HP/LP-UNEQ defect, unequiped01 unspecified02 TUG structure03 blocked TU04 34 or 45 Mbit/s

12: 140 Mbit/s 13: ATM14: DQDB15: FDDI

H4: > TU-LOM alarm Loss of Multiframexxxxxx00 - pointer points V1xxxxxx01 - pointer points V2xxxxxx10 - pointer points V3xxxxxx11 - pointer points V4

RDI


Lower order path overhead (HO-POH) C2, C12, C11

BIP-2V5:

REI (Receive Error Indication) > LP - REI error shows the detection of a far error

REI(FEBE)

RFI RDI

BIP-2 bit 1: odd bit parity of de previous VC. bit 2: even bit parity

L1 L2 L3

RDI (Remote Defect Indication) > LP - RDI defect

L1-L3 VC path label > P - SLM alarm Signal Label Mismatch

000 - Unequipped > LP-UNEQ alarm001 - Unspecified status010 - Asynchronous floating011 - Synchronous floating bit oriented100 - Synchronous floating byte oriented

V5

J2

N2

K4

Path Overhead

Reserved for its use by the operator. It can be used for tandem connection monitoring

Tandem connection monitoring (TCM)Trace protectionbits 1-4 APS bits 5-7RDI

RFI (Remote Failure Indication) > LP - RFI alarm, path protection indicator

Low Order Path Trace


Section overhead (SOH)

Path overheads can detect transmission errors from the receiver side but it can’t identify where those errors rose. This is one of the missions of the section overhead: RSOH (Regenerator Section Overhead) and MSOH (Multiplexer Section Overhead)

AU Pointer

B 2 B 2 B 2 K 1 K 2

S 1

D 4

D 7

D10

D 5

D 8

D11

D 6

D 9

D12

M 1 E 2

*A 1

*

B 1

D 1

A 1*

A 1*

A 2 A 2* *

E 1

D 2

A 2J 0C 1

**

F 1

D 3

* D1..D3: 192 kbit data communications channel

D4..D12: 576 kbit/s data communications channel

E1: 64 Kbit/s voice service channel between regenerators

* Non scrambled bytesX Bytes reserved for national use^ Media dependent bytes. S1: clock source

10101010 - valid0000 - unknown0010 - G.811 primary clock0100 - G.812 transit clock1000 - G.812 local clock1011 - G.813 synchronous equipment1111 - non synchronized

01010101 - invalid

E2: 64 Kbit/s voice service channel between multiplexers

F1: 64 Kbit/s voice or data service channel between regenerators

M1: re-sending of B2 errors, coded over 8 bits implies REI (FEBE)

K1, K2: APS protection channel > wrong K1, K2 alarm

bits 5-8

K1: Request of a channelbits 1-4 : kind of request (manual, signal failure(SF), degradation(SD)...)bits 5-8 : requested channel number

K2: far answer

bits 1-4: connected channel number (0=null channel)bit 5: architecture type (0 for 1+1, and1 for 1:n)bit 6-9: > MS AIS alarm if 1111, > error indication if 110

MS

OH

RS

OH

A1= 11110110 A2= 00101000: frame alingment

B1: Bit interleaved parity, regenerator section (BIP-8)

B2: Bit interleaved parity, multiplexer section (BIP-24)

J0/C1: STM-1 identifier in STM-n


Overhead management (i)

S T M - M S T M - M

A D MS D HM U X

S T M - M

M >N

R E GL O - P T E H O - P T E

2M

34M

140M

S T M - 1STM-N

STM-NS T M - M S T M - M L O - P T EH O - P T E

2M

34M

140M

S T M - 1

M >ND X C R E G R E G H O - P T E L O - P T E

STM-N

PDHPDH

SECTION

REGENERATOR

SECTION

MULTIPLEXING

PATHHIGH ORDER

PATHL O W O R D E R

SECTION

REGENERATOR

SECTION

REGENERATOR

SECTION

REGENERATOR

SECTION

REGENERATOR

SECTION

REGENERATOR

SECTION

MULTIPLEXING

SECTION

MULTIPLEXING

L O - P O H

H O - P O H R S O H / M S O H R S O H R S O H R S O HR S O H / M S O H R S O H / M S O H R S O H / M S O H

L O - P O H

H O - P O H


Overhead management (ii)

Cada tara es gestionada exclusivamente por dos nivel correspondientes pareja contiguas de elementos de red contiguos. Ningún otro nivel pude manipularlos lícitamente.

LO

VC11VC12

HO

VC3VC4

POH POHMSOH RSOH

LO

VC11VC12

HO

VC3VC4

POHPOHMSOHRSOHRSOH

multiplexer multiplexerregenerator

B3-G1J1

C2-H4K3

F2-F3-

N1

V5J2-

K4--

N2

B2-M1J0-

K1-K2E2

D4-D12-

B1J0--

E1-F1D1-D3

-

B1J0--

E1-F1D1-D3

-

B1J0--

E1-F1D1-D3

-

B3-G1J1

C2-H4K3

F2-F3-

N1

V5J2-

K4--

N2

B2-M1J0-

K1-K2E2

D4-D12-

B1J0--

E1-F1D1-D3

-

B1

B2

B1

B3

V5

Multiplexer sectionRegenerator section

Higher order path

Lower order path

Regenerator section

Section

Pointers

Pointers 22/55© Trend Communications

The pointer mechanism

All the elements inside the SDH network must be synchronized with only one master clock but:

•• is very difficult avoid little deviations in clock signals

•• networks of different operators and with different master clocks must be connected

•• Long filter buffers bring delays to the received signal

A solution is to use moving pointers. These buffers don’t avoid using input buffers but the their size is smaller an so the delay

A pointer points to the POH control information of the VC traffic channel

POH

J1B3

C2G1

H4F3K3N1

27010 11

F2

H1 H2 H3 H3 H3Y Y 1 1

VC-4

+


AU-4 and TU-3 pointers

•• Bits 1 0 of the H1 byte shows that it is an AU-4 or TU-3

•• Range of AU-4: from 0 to 782

•• Range of TU-3: from 0 to754

•• H3 is formed by 3 bytes if it is an AU-4 or 1 byte if it is a TU-3

•• Invert five D bits for negative justification and five I bits for positive justification

•• Concatenation indication (CI): H1=1001RR11, H2=11111111

•• Null pointer indication (NPI) (only TU-3): H1=1001RR11, H2=11100000

POH

J1

B3

C2

G1

H4F3

K3

N1

27010 11

F2

H1 H2 H3 H3 H3Y Y 1 1

VC-4

+H 1

H 3

H 2 +

862 3

1

9

G 1

H4

F3

K 3

N1

F2

J1

B 3

C 2

VC-3

TU-3

N N N N

pointer va lue

(10 b i t s )

D D

H1 H2 H3

negative justification

1 0 D D DD D D

positive justif ication

: increase bit

: new data f lag (NDF)

: decrease bitD

N NDF enabled:

N D F disabled :

1 0 0 1

0 1 1 0

NDF

I

I I I I I

Y: 1011SS11 (unspecif ied SS bits) 1: 11111111


TU-2 and TU-12 pointers

•• Range of TU-2: from 0 to 427

•• Range of TU-12: form 0 to 139

•• For negative justification invert five D bits, for positive invert five I bits

•• Concatenation indication (CI) V1 = 1001RR11, V2 = 11111111

H4 = X X X X X X00

H4 = X X X X X X01

H4 = XXXXXX10

H4 = XXXXXX11

v1TU-12

1

35 bytes

P T R

4

9

1

v2

v3

v4

35 by te s


35 by te s

35 by te s

35 by te s

V1: 1st pointer byte V2: 2nd pointer byte V3: 3rd byte (action)V4: reserved

125 ms

500 ms

H4 = XXXXXX 00

H4 = XXXXXX 01

H4 = XXXXXX10

H4 = XXXXXX11

v1TU-2

1

107 bytes

107 bytes

P T R

12

9

1v2

v4

107 bytes

107 bytes

107 bytes


v3 500 ms

125 ms

N N N N

pointer value (10 bits)

D D

V1 V2 V3

: increase bit

: New data f lag (NDF)

: decrease bit

N D F enabled :

N D F disabled :

1 0 0 1

0 1 1 0


S S s i z e

S S D D DD D D

D

N

positive justification

NDF

I I I I I

0 0 TU-21 0 TU -12

I


Pointer Regeneration


Pointer reading

125µs

125µs

J1

AU Pointer 0 0

782782AU Pointer

J1

J1

Drop the VC-4

0 1 1 1

7827817817810 0

782782

0 1 1 1

782781781781


Pointer adjustment


Justification mechanism


Case 1: clock transparency (i)

1 - B doesn’t see pointer movement because the 2 Mbit/s frame and the STM-1 are created in A with the same clock. B send the STM-1 with R2 and the pointer moves like a function f (R1 -R2)

2 - Nothing happens because C multiplexer uses the same clock like B

3 - The VC4 will be extracted like R1 altough the STM-1 has arrived with R2 frecuency. At B the STM is sent at R3 and the pointer moves like a function f (R1-R3)

STM-1

B

E

D

C

R2

R3

R1

A

STM-1

2Mbit/s

1

2

4

5 6

3


Case 1: clock transparency (ii)

4 - E multiplexer doesn’t generate pointer movement because it uses the same clock like D

5 - At B the VC4 is extracted like R1 altough it has arrived in the STM-1 at a R3 frequency. At B the STM-1 is sent at R3 and the pointer moves like f(R1-R2).

6 - A multiplexer receive the STM-1 like R2 but the VC12 arrives at the first rate R1!!

STM-1

B

E

D

C

R2

R3

R1

ASTM-1

2Mbit/s

1

2

4

5 6

3

cclloocckk ttrraannssppaarreennccyy!!!!!!


Case 2

If the R1 clock synchronizes R2 then the STM-1 frame won’t have pointer movements beacuse:

•• R1 = R2 then f(R1-R2) = f(0) = Cte.

In points 3 and 5 will be yet exist pointer movements. In order to finish with all movements R1 must be synchronized with R3 too.

STM-1

B

E

D

C

R2

R3

R1

A

STM-1

2Mbit/s

1

2

4

5 6

3


Pointer actions

P shows how many pointer movements are made in one second while the horizontal axis shows de frequency correction met

1 VC - 4 f r ame = 261 x 9 x 8 b i t s = 18792 b i t s

VC -4 t r an sm i s s i on r a t e = = 150336000 b i t / s

∆∆f

1 2 5 µs

f0

P a c t i o n s

s

24 b i ts

1 ac t i on

1 s

1 5 0 3 3 6 0 0 0 b i t s = . . = P x 1 . 6 E - 7 : c l o c k a d j u s t emen t g o t w i t h P p o i n t e r movemen t s

∆∆f

f0

= P x 1 . 6 E - 7

PM A X

= = 2000 acc i ones / s1 a c c i ó n

4 t r amas

1 t r a m a

1 2 5 µs .

F o r b i d d e n

P

0 . 0 2

0 . 2

2

2 0

2 0 0

2 0 0 0

∆f

f 0

P M A X : max imum po in te r a c t i v i t y o n l y one po i n t e r movemen t i s po s s i b l e i n f ou r f r ames

2000 x 1 ,6E-7= 3 ,2 x 10E-4 ∆∆f

f0

m a x =

tha t i s t he max imum f r equency co r r e c t i on

18792 b i t s


STM-N frame creation

Multiplexing process in STM-N, N=4,16, 64

STM-1 at 155Mbit/s, STM-4 at 622Mbit/s, STM-16 at 2,5Mbit/s, STM-64 at 10Gbit/s

1

261

9

1

Carga úti l de

270

9

9

4

5

1

3123...N123...N

R S O H

M S O H

N x 261

9

# 1

1

261

9

1

Carga úti l de

270

9 # 2

1

261

9

1

Carga úti l de

270

9 # N

N x 9

123...N123...N

T U G T U G T U G

S T M - N


Concatenation and multiplexing

In a STM-N frame that is the result of STM-1 frame multiplexion there are 4 pointers of lower order STM-M (N=4M) and the useful load is divided for each component.

One concatenated STM-N groups all the useful load for only one client. For example, an ATM network, that is, there are only one pointer for the load.

H1 Y Y H2 1 1 H3 H3 H3

H1 H2 H3

H1 Y Y.......

STM-0(SONET STS-1)

STM-1(SONET STS-3c)

12 bytes

H2 1 1.......12 bytes

H3 H3 H3.......12 bytes

3 bytes 3 bytes 3 bytes

3 bytesx 3 frames

x 4 frames

STM-4(SONET OC-12)

pointer increments in a byte oriented way

1 increment = 3 bytes

1 increment = 12 bytes

Section

Maintenance

Maintenance 36/55© Trend Communications

Anomalies, Defects, Errors, Alarms and Failures

•• Anomaly: Is the least disagreement that can be observed between the measured and the expected characteristics of a network element without service interruption (for example a parity error)

•• Defect: A defect level is reached when de anomaly density is high enough to interrupt a re-quested function (for example a loss of signal).

•• Damage: A damage is is produced when a function can’t finish a requested action. This sit-uation doesn’t comprise incapacities caused by preventive maintenance.

•• Fault: The cause of a damage without interruption for a time long enough that makes pos-sible to consider that a network element can’t achieve a recuested function

•• Alarm: An obserbable indication that points to a fault (revealed damage) that usually shows an indication of the damage depth, for example a LED or a siren

Errors reflect anomalies and alarms show defects and ofen those words are used to speak about the formers.

All are grouped under the common term of events.


Causes for the disfunctions

Nowadays, high capacity transmission systems are robust but they are yet vulnerable to some effects like:

•• Termal noise, always present in regeneration systems. It is produced by electron activity due to temperature. This noise is matematically well modelled and it follows a gaussian dis-tribution

•• Degraded lasers, often lasers lose capabilities due to the use and their power decreases. In this situation de signal/noise ratio may be poor

•• Rayleigh scattering, in radio systems

•• Rain and humidity atenuations

•• Electrostatic discharges, lightnings and human discharges when equipment is touched with-out preventions

•• Satellites and radiotransmitters are often affected by sun radiations

•• Degradation of electric connections, most of the systems are optoelectric and metalic parts are exposed to oxidation and erosion processes

•• Bad synchronization of network elements is one of the most important error causes. Jitter and wander effects are intications of potential problems

•• Design errors in equipment or infrastuctures


SDH events associated with sections

Are events associated with the SOH overheads and the network elements that manage them. That is, they are the Regeneration and Multiplexing Sections

Level Event Type How Cause

LOS Alarm Total signal absence

RSOH

LOF Alarm Loss of frame

OOF Alarm A1-A2 Out of frame

LSS Alarm Loss of signal synchronization

EFAS Alarm A1-A2 Frame alignment sequence error

Error B1 Error B1 Verification of BIP-8 parity error

MSOH

MS-AIS Alarm K2=xxxxx111 Alarm indication signal, multiplexer section

MS-RDI Indication K2=xxxxx110 Remote defect indication, multiplexer section

Error B2 Error B2 Verification of BIP-24 parity error

MS-REI Indication M1=nnnnnnnn Remote error indication, multiplexer section

Puntero AU

B 2 B 2 B 2 K 1 K 2

S 1

D 4

D 7

D10

D 5

D 8

D11

D 6

D 9

D12

M1 E 2

*A 1

*

B 1

D 1

A 1*

A 1*

A 2 A 2* *

E 1

D 2

A 2J 0C 1

**

F1

D 3

*

RSOH

MSOH


SDH events associaded with paths

They are events identified by the pair of multiplexers defining a path. There are two kinds of paths, higher order paths (HOP) lower order paths (LOP) there are two different groups of events.

HO Path

HP-RDI Indication G1=xxxx1xxx Remote defect indication, higher order pathHP-TIM Alarm J1 Trace identifier mismatch, higher order pathHP-UNEQ Indication C2=00000000 Unequiped higher order pathHP-PLM Error C2 Payload mismatch, higher order pathHP-REI Indication G1=nnnnxxxx Remote error indication, higher order pathHP-B3 Error B3 B3 parity error, higher order path

LO Path

LP-RDI Indication V5=xxxxxxx1 Remote defect indication, lower order pathLP-TIM Alarm J2 Trace identifier mismatch, lower order pathLP-UNEQ Indication V5=xxxx000x Unequiped lower order pathLP-PLM Alarm V5=xxxxnnnx Payload mismatch, lower order pathLP-RFI Indication V5=xxx1xxxx Remote failure indication, lower order pathLP-REI Indication V5=xx1xxxxx Remote error indication, lower order pathLP-B3 Error B3 B3 parity error, lower order pathBIP-2 Error V5=nnxxxxxx BIP-2 Parity error

J1B3C2G1F2H4F3K3N1

V5

J2

N2

K4

HO-POH HO-POH


SDH events associated with pointers

They are events identified with pointers. The AU pointer in STM-1 basic frame an the TU pointer in low rate tributaries transported

AU ptr

AU-AIS Alarm all “1s” Alarm indication signal, administrative unit

AU-LOP Alarm H1-H2 Loss of pointer, administrative unitAU-PJE Pointer H1-H2 AU pointer justification eventAU Incr Pointer H1-H2 AU pointer increased

AU Decr Pointer H1-H2 AU pointer decreasedAU NDF Pointer H1-H2 New data flag in AU pointerAU Inv Pointer H1-H2 AU pointer inversion

TU ptr

TU-LOM Alarm H4 Loss of multiframe of tributary unitTU-AIS Alarm “all 1s” Alarm indication signal, tributary unitTU-LOP Alarm V1-V2 Loss of TU pointer

TU-PJE Pointer V1-V2 TU pointer justification eventTU Incr Pointer V1-V2 TU pointer increasedTU Decr Pointer V1-V2 TU pointer decreased

TU NDF Pointer V1-V2 New data flag in TU pointer

AU ptr TU ptr

N N N N

pointer value(10 bits)

D D

H1 H2 H3


1 0 D D DD D D

positive justification

: increase bit

: new data flag (NDF)

: decrease bitD

N NDF enabled:

NDF disabled :

1 0 0 1

0 1 1 0

NDF

I

I I I I I

Y: 1011SS11 (unspecified SS bits) 1: 11111111

N N N N

po in te r va lue

(10 b i t s )

D D

V 1 V 2 V 3

: inc rease b i t

: New da t a f l a g (NDF )

: dec rease b i t

NDF enabled:

NDF disabled :

1 0 0 1

0 1 1 0

negative just i f icat ion

S S s i ze

S S D D DD D D

D

N

positive just i f icat ion

NDF

I I I I I

0 0 TU - 21 0 TU -12

I


Summary of SDH events

Level ID Type How MeaningLOS Alarm Loss of Signal

RSOH

LOF Alarm Loss Of FrameOOF Alarm A1-A2 Out Of FrameLSS Alarm Loss of Sequence SynchronizationEFAS Alarm A1-A2 Error in Frame Alignment SignalError B1 Error B1 Error B1

MSOH

MS-AIS Alarm K2=xxxxx111 Multiplexion Section - Alarm Indication SignalMS-RDI Indication K2=xxxxx110 Multiplexion Section - Remote Defect IndicationError B2 Error B2 Error B2MS-REI Indication M1=nnnnnnnn Multiplexion Section - Remote Error Indication

HP

HP-RDI Indication G1=xxxx1xxx Higher order Path - Remote Defect IndicationHP-TIM Alarma J1 Higher order Path - Trace Identifier MismatchHP-UNEQ Indication C2=00000000 Higher order Path - UnequippedHP-PLM Error C2 Higher order Path - Payload Label MismatchHP-REI Indication G1=nnnnxxxx Higher order Path - Remote Error IndicationHP-B3 Error B3 Higher order Path - B3 error

LP

LP-RDI Indication V5=xxxxxxx1 Lower order Path - Remote Defect IndicationLP-TIM Alarma J2 Lower order Path - Trace Identifier MismatchLP-UNEQ Indication V5=xxxx000x Lower order Path - UnequippedLP-PLM Alarma V5=xxxxnnnx Lower order Path - Payload Label MismatchLP-RFI Indication V5=xxx1xxxx Lower order Path - Remote Failure IndicationLP-REI Indication V5=xx1xxxxx Lower order Path - Remote Error IndicationLP-B3 Error B3 Lower order Path - B3 errorBIP-2 Error V5=nnxxxxxx Bit Interleave Parity - 2

AU

AU-AIS Alarm todo “1s” Administrative Unit - Alarm Indication SignalAU-LOP Alarm H1-H2 Adminastrative Unit - Loss Of PointerAU-PJE Pointer H1-H2 Administrative Unit - Pointer Justification EventsAU Incr Pointer H1-H2 Administrative Unit pointer - IncrementAU Decr Pointer H1-H2 Administrative Unit pointer - DecrementAU NDF Pointer H1-H2 Administrative Unit pointer - New Data FlagAU Inv Pointer H1-H2 Administrative Unit pointer - Inversion

TU

TU-LOM Alarm H4 Tributary Unit - Loss Of MultiframeTU-AIS Alarm “todo 1s” Tributary Unit - Alarm Indication SignalTU-LOP Alarm V1-V2 Tributary Unit - Loss Of PointerTU-PJE Pointer V1-V2 Tributary Unit - Pointer Justification EventsTU Incr Pointer V1-V2 Tributary Unit pointer- IncrementTU Decr Pointer V1-V2 Tributary Unit pointer - DecrementTU NDF Pointer V1-V2 Tributary Unit pointer - New Data FlagTU Inv Pointer V1-V2 Tributary Unit pointer - Inversion


Alarms

They happen at different levels:

•• in the section level: regeneration y multiplexion,

•• in higher order path and lower order path

An alarm signal (AIS) is activated under standarized criteria and is sent forward to notify the event to the next network element. As an answer to a received AIS a remote defect indication is sent backwards

An RDI is indicated in a specific byte while an AIS is a secuence of “1” in the space deticated to the load because de affected element can’t access to the information.

Una AIS es una secuancia de bytes todos a “1” en el espacio dedicado a carga puesto que el elemento afectado por la alarma no puede acceder a la información. Mientras que el RDI se indica en un byte específica. A failure sent in a transmission way doesn’t depends on the failure in the other transmission way


ITU alarm detection criteria

Alarm Criteria

OOFDetection: before 625µsRealignment: before 250µs

LOFDetection: from 0 to3 ms in OOFRealignment: from 0 to 3 ms without OOF

LOPDetection: from 8 to 10 invalid ptrs. or from 8 to10 consecutive NDF (New Data Flag) Realignment: 3 consecutive valid pointers

MS-RDIDetection: 3 consecutive frames with K2=xxxxx110Realignment: 3 consecutive frames with K2<>xxxxx110

MS-AISDetection: 3 consecutive frames with K2=xxxxx111

Realignment: 3 consecutive frames with K2<>xxxxx111

AU-AISTU-AIS

Detection: 3 consecutive pointers with all bits to 1 (H1-H2 o bien V1-V2)

Realignment: 3 consecutive valid pointers or 1 NDF (New Data Flag)

LSS Loss of Sequence Synchronization: if BER > 2x10-1 in 1s.

LOSDesirable detection: between 10 and 50µs

Obligatory detección: before 50µs


OAM: detected events at the end of a LOP

•• Any loss of pointer (AU-LOP) or an alarm (AU-AIS) generate: a PDH-AIS forwards and a HO-RDI backwards

•• Any parity error in the tributary (V2 bip2) generate a LO-REI backwards

PDH AIS(A l l 1 s )

LO-RDI(V5=xxxxxxx1 )

LO-REI(V5=nº of detected er rors)

V5=xx nx xxxx; Errors=0..2

B I P - 2 ( V 5 ) w i t h e r r o r s

A U - A I S(A l l 1 s )

A U - L O P

M U X R E GL O - P T E H O - P T E

2 M

3 4 M

1 4 0 M

STM-1 STM-NL O - P T EH O - P T E

2 M

3 4 M

1 4 0 M

STM-1

H O - P T E L O - P T EM U X

M U L T I P L E X E R

S E C T I O N

S E C T I O N

H I G H O R D E R

P A T H

L O W O R D E R

P A T H

R E G E N E R A T O R

S E C T I O N



OAM: detected events at the end of a HOP

AIS: Alarm Indication Signal

HO-REI: High Order Remote Error Indication

TU-AIS(A l l 1 s )

PDH AIS(A l l 1 s )

HO-RDI(G1=xxxx1xxx )

LO-RDI(V5=xxxxxxx1)

HO-REI(G1=nº o f detec ted er rors )G 1 = n n n nxxxx; Errors=0..8

A U - A I S(A l l 1 s )

A U - L O P

B 3 w i t h e r r o r s


2 M

3 4 M

1 4 0 M


2 M

3 4 M

1 4 0 M

STM-1



S E C T I O N

S E C T I O N

H I G H O R D E R

P A T H

L O W O R D E R

P A T H


S E C T I O N



OAM: detected events at the end of a MS

MS-RDI: Multiplexer Section Remote Defect Indication

L O S

L O F

A U - A I S

( A l l 1 s )

TU-AIS

( A l l 1 s )

P D H A I S

( A l l 1 s )


M S - R D I

( K 2 = x x x x x 1 1 0 )

H O - R D I(G1=xxxx1xx x )

L O - R D I

( V5=xx x x x x x1 )

M S - R E I(M1=nº o f de tec t ed e r ro r s )

M1=nnnnnnnn; E r ro r s=0 . .24


2 M

3 4 M

1 4 0 M


2 M

3 4 M

1 4 0 M

STM-1



S E C T I O N

S E C T I O N

H I G H O R D E R

P A T H

L O W O R D E R

P A T H


S E C T I O N



OAM: Detected events at the end of a RS

L O S

L O F

MS-AIS ( A1 , A2 OK ; t he r e s t a l l 1 s )

AU-AIS(A l l 1 s )

TU-AIS(A l l 1 s )

PDH AIS(A l l 1 s )


MS-RDI(K2=xxxxx110)

HO-RDI(G1=xxxx1xxx )

L O - R D I(V5=xxxxxxx1)


2 M

3 4 M

1 4 0 M


2 M

3 4 M

1 4 0 M

STM-1



S E C T I O N

S E C T I O N

H I G H O R D E R

P A T H

L O W O R D E R

P A T H


S E C T I O N



Anomaly and defect management

AIS: Alarm indication signalRDI: Remote defect indication

REI: Remote error indication

HPA: Higher order path adaptationHPC: Higher order path connection

HPOM: Higher order path monitor

HPT: Higher order path terminationHUG: Higher order unequipped generator

LPA: Lower order path adaptation

LPC: Lower order path connectionLPOM: Lower order path monitor

LPT: Lower order path termination

LUG: Lower order unequipped generatorLOF: Loss of frame

LOM: Loss of multiframe

LOP: Loss of pointerLOS: Loss of signal

MSA: Multiplexer section adaptation

MST: Multiplexer section terminationRST: Regeneration section termination

SPI: SDH physichal interface

SLM: Signal label mismatchTIM: Trace identifier mismatch

UNEQ: Unequipped signal

SPI RST MST MSA HPOM HUG HPC HPT HPA LPOM LUG LPC LPT LPA

LOS

LOF

Error B1

“1”

“1”regenerated signal

MS-AIS“1”

Error MS-Exc. (B2)

Error MS-BIP (B2)

MS-RDI

MS-RDI

AU-AIS

AU-LOP

AU-AIS

“1”

“1”

HP-TIMHP-SLM

“1”

HP-REI

HP-RDI

HP-RDI

HP-REI

TU-AIS

TU-AIS “1”

“1”

“1”

phys.section

regen.section

multiplexersection Higher order path Lower order path

HO path signal

HOVC with POH y and unspecified useful load

HO unequipped signal

HP-UNEQ

Error HP-BIP (B3)

HPC unusedoutput/HP-UNEQ

HP-LOM/TU-LOP HPC unusedoutput/LP-UNEQ

LP-TIM

LP-SLM

LP-REI

LP-RDI

LP-RDI

LP-REI

LP-UNEQ

Error LP-BIP (B3)

Detection

Generation

AIS Insertion

Detection/Generation

“1”

(Note 1)


AIS formats

•• MS-AIS: All bits excepting the ones of the RSOH are put to the binary value ‘1’.

•• AU-AIS: All bits of the adminsitrative unit are put to ‘1’ but the RSOH and MSOH maintains their codification.

•• TU-AIS: All bits in the tributary unid are put to ‘1’ but the unaffected tributaries and the RSOH and MSOH maintains their codification.

•• PDH-AIS: All the bits in the tributary are ‘1’.

RSOH

MSOH

RSOH

MSOH

K2

PTR PTR

RSOH

MSOH

PTR

: X= 1

AU-AIS TU-AIS PDH-AIS MS-AIS

Section

Some conclusions


SDH means infrastructures standardization

A SDH network can offer transport services to final users or it can be used as a transport infrastructure by a GSM, ISDN, ATM, Frame Relay, UMTS..., network.

ATM

GSM

UMTS

SDH

SDHnode

SDHnode

Frame Relay

STM-N


Simple and reliable

Simple•• Direct tributaries add&drop avoiding the typical PDH mux/demux

•• The tributaries are synchronized to the network

•• Byte oriented justification; stuffing bits are not necessary

•• Tributaries can be drop&insert to the signal dynamically without disturbing the signal.

•• The High efficiency level reached is a consequence of management facilities

•• It is cheaper to provide new service

Reliable•• SDH is byte oriented allowing the integration of telecommunications with computers

•• Automatic reconfiguration is possible to prevent faults

•• Multiplexers provide a high reliability equivalent similar in backbones and in regional areas

•• Hierarchical management of alarms and maintenance functions by the network elements.


New services

•• As a consequence of higher capacity and quality

•• Transport for high definition audio and video

•• High speed data for Internet or other networks

•• Fast bandwidth management to answer requirements

•• Integration under the same arquitecture circuit and packet networks.

Services

Telephony

Frame RelayUMTS

GSM

Infrastructures

SDH ATMSDH link

ATM access

FrameRelay

IWU

Host

Superserver


Cost effective

•• Universal standard: multivendor

•• Maintains the compatibility with legacy PDH networks

•• Reduces the number of network elements to provide advanced services

•• With just a few network elements is possible to configure a network

•• Simplifies the management because of centralized configurations

•• Fast traffic routing in case of fault

SDH network

SDH access

SDH ring2,5 Gb/s

Interconnected rings

point ot point45 Mb/s

PDH access

622 Mb/s


Telecom basis in the next 10 years?

“SDH will be the dominant technology in the next 10 years” as Pioneers Optical Edge Networks Boston (MA) June 2000 said

•• IP, MPLS, DWDM, will be attention focus of investements of 2,5 billion $

•• Investements in SONET/SDH tecnology will be about 6 billion $

SDH~Different Overview

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