sdh~different overview
TRANSCRIPT
© 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
Transportation of a 2 Mbit/s circuit 4/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 5/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 6/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 7/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 8/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 9/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 10/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 11/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 12/55© Trend Communications
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
*
Transportation of a 2 Mbit/s circuit 14/55© Trend Communications
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
Assembling ofVC-11 , VC-12
C-11, C-12
C-3, C-4MUX
STM-N
Assembling of VC-3 , VC-4
Assembling ofVC-11 , VC-12
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
Transportation of a 2 Mbit/s circuit 15/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 16/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 17/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 18/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 19/55© Trend Communications
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
Transportation of a 2 Mbit/s circuit 20/55© Trend Communications
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
+
Pointers 23/55© Trend Communications
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
Pointers 24/55© Trend Communications
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
PTR: V1, V2, V3 ó V4
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
PTR: V1, V2, V3 ó V4
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
negative justification
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
Pointers 25/55© Trend Communications
Pointer Regeneration
Pointers 26/55© Trend Communications
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
Pointers 27/55© Trend Communications
Pointer adjustment
Pointers 28/55© Trend Communications
Justification mechanism
Pointers 29/55© Trend Communications
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
Pointers 30/55© Trend Communications
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!!!!!!
Pointers 31/55© Trend Communications
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
Pointers 32/55© Trend Communications
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
Pointers 33/55© Trend Communications
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
Pointers 34/55© Trend Communications
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.
Maintenance 37/55© Trend Communications
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
Maintenance 38/55© Trend Communications
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
Maintenance 39/55© Trend Communications
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
Maintenance 40/55© Trend Communications
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
negative justification
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
Maintenance 41/55© Trend Communications
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
Maintenance 42/55© Trend Communications
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
Maintenance 43/55© Trend Communications
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
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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
R E G E N E R A T O R
Maintenance 45/55© Trend Communications
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
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
R E G E N E R A T O R
Maintenance 46/55© Trend Communications
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 )
B 2 w i t h e r r o r 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
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
R E G E N E R A T O R
Maintenance 47/55© Trend Communications
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 )
B 1 w i t h e r r o r s
MS-RDI(K2=xxxxx110)
HO-RDI(G1=xxxx1xxx )
L O - R D I(V5=xxxxxxx1)
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
R E G E N E R A T O R
Maintenance 48/55© Trend Communications
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)
Maintenance 49/55© Trend Communications
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
Maintenance 51/55© Trend Communications
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
Maintenance 52/55© Trend Communications
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.
Maintenance 53/55© Trend Communications
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
Maintenance 54/55© Trend Communications
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
Maintenance 55/55© Trend Communications
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 $