sdh theory
DESCRIPTION
SDH TheoryTRANSCRIPT
SDH Theory
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Chapter – 1 SDH Theory
Objectives
• Introduction to SDH– Multiplexing– STM-1 frame– Virtual Containers (VCs)– TU coordinates– STM-N frame– SDH layers and trails– SDH network elements– SDH overhead– Mapping
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Chapter – 1 SDH Theory
What is SDH?• SDH = Synchronous Digital Hierarchy• It is a transport network
– synchronous– fully standardized– with high bandwidth– for synchronous and asynchronous signals– for future broadband signals and new services– with standardized network management capabilities– with traffic protection– with a flexible multiplexing structure
• direct access to tributaries• cross-connections without demultiplexing
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Chapter – 1 SDH Theory
Digital Transmission System
• Regenerator– recreates the signal.
• Multiplexer (MUX)– Multiplexer combines data from
several lines and transmits itover a higher-capacity data link.
No signal
60 km
R
60 km
Regenerator
MUX MUX
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Chapter – 1 SDH Theory
• Add-Drop Multiplexer (ADM)– Part of the traffic is terminated.– Part of the traffic goes transparently
through.
Multiplexer Naming Conventions
TMm/n
aggregate
tribut arie s
ADMm/n
aggregateaggregate
tributaries
• Terminal Multiplexer (TM)– All traffic is terminated here.– m: aggregate level– n: lowest tributary level
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Chapter – 1 SDH Theory
• No traffic is terminated.• Cross-connection matrix
connects tributary signals of one aggregate to another aggregate.
Digital Cross-connect (DXC m/n)
PDHMUX
PDHMUX
PDHMUX
PDHMUX
DDF
SDHCross-Connect
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Chapter – 1 SDH Theory
PDH vs. SDH — Bit Rates
SONET(ANSI)
SDH(ITU-T)
Data rate(Mbps)
STS-1 51.84STS-3 STM-1 155.52STS-9 466.56STS-12 STM-4 622.08STS-18 933.12STS-24 1244.16STS-36 1866.24STS-48 STM-16 2488.32
STM-64 9953.28
Hierarchy level USA Europe0 64 kbit/s T0 64 kbit/s E01 1.544 Mbit/s T1 (24x) 2.048 Mbit/s E1 (32x)2 6.312 Mbit/s DS-2 (4x) 8.448 Mbit/s E2 (4x)3 44.736 Mbit/s DS-3 (7x) 34.368 Mbit/s E3 (4x)4 139.264 Mbit/s E4 (4x)
E1E0
E2E3
E4plesiochronous
plesiochronous
plesiochronous
synchronous
TM STM-1
TM STM-4
TM STM-16
• E1 (2.048 Mbit/s)
• T1 (1.544 Mbit/s)
• DS-2 (6.312 Mbit/s)
• E3 (34.368 Mbit/s)
• DS-3 (44.736 Mbit/s)
• E4 (139.264 Mbit/s)
• ATM
• etc.
PDH
SDH
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Chapter – 1 SDH Theory
PDH vs. SDH — Add & Drop Function
ADM STM-4STM-4
Six TMs neededto drop E1
One ADM isenough to drop E1.
TM TM
TMTM
TMTM
E3
E3
E3
E2
E2
E1
E1
E1
E4 E4
E1 (2.048 kbit/s)
E2
2/1 2/1
3/23/2
4/3 4/3
PDH SDH
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Chapter – 1 SDH Theory
STM-1 Frame
2430 bytes/frame × 8 bit/byte × 8000 frame/s = 155.52 Mbit/stransmitted from top to bottom and left to right
AU-4 pointers
MSOH
PayloadVC-4 (HO-VC)
RSOH
9 ro
ws
(byt
es)
9
5
261
270 columns (bytes)
3
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Chapter – 1 SDH Theory
155.520 Mbit/s serial signal
9 BYTES + 261 BYTES = 270 BYTES 270 BYTES x 9 = 2430 BYTES
2430 BYTES/FRAME x 8 BITS/BYTE x 8000 FRAMES/SEC = 155.520 Mbit/s
125us
1 2 3 4 5 6 7 8 9
2430 b yte s
261 b yte s9 b yte s 261 b yte s9 b yte sO ve rhe a d p a y lo a d
F F F F
261 b yte s9 b yte s261 b yte s9 b yte s261 b yte s9 b yte s261 b yte s9 b yte s261 b yte s9 b yte s261 b yte s9 b yte s261 b yte s9 b yte s261 b yte s9 b yte s
STM -1 Frame
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Chapter – 1 SDH Theory
C4 4. level 140 Mbit/s
C3 3. level 34/45 Mbit/s
C2 2. level 6 Mbit/s
C1.2 1. level 2 Mbit/s
C1.1 1. level 1.55 Mbit/s
E4 (139.264 Mbit/s)
Virtual Containers (VCs)
VC-3
VC-4
VC-12VC-11
VC-2
E1 (2.048 Mbit/s)T1 (1.544 Mbit/s)
DS-2 (6.312 Mbit/s)
E3 (34.368 Mbit/s)
DS-3 (44.736 Mbit/s)
ATM cells
Mapping
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Chapter – 1 SDH Theory
VC-4STM-N× N
× 3× 1
× 3
× 7
139 264 kbit/s
44 736 kbit/s34 368 kbit/s
6312 kbit/s
2048 kbit/sPointer processing
Multiplexing
Aligning
Mapping1544 kbit/s
CTPpassing connectionContains: payload pointer...
TTPend of trailContains: path trace,
signal label, error detection…
AUG AU-4
TUG-3
TUG-2
TU-3
TU-2
TU-12
VC-2
VC-3
VC-12
VC-11
C-4
C-3
C-2
C-12
C-11
× 1
C-n Container-n
SDH Multiplexing Structure (ETSI)
× 1
ITU-T
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Chapter – 1 SDH Theory
VC-4STM-N× 1× N
× 3
× 3× 1
× 3
× 4
× 7× 7
139 264 kbit/s
44 736 kbit/s34 368 kbit/s
6312 kbit/s
2048 kbit/sPointer processing
Multiplexing
Aligning
Mapping1544 kbit/s
• TTP– end of trail– Contains: path trace,
signal label, error detection…
• CTP– passing connection– Contains: payload pointer...
AUG
AU-3
AU-4
VC-3
TUG-3
TUG-2
TU-3
TU-2
TU-12
VC-2
VC-3
VC-12
VC-11
C-4
C-3
C-2
C-12
C-11
× 1
TU-11
C-n Container-n
SDH Multiplexing Structure (G.707)
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Chapter – 1 SDH Theory
KLM: 300
KLM CoordinatesAU-4 pointers
MSOH
PayloadVC-4 (HO-VC)
RSOH
VC-4
POH
VC-12
VC-12
K
L
TU12-1 TU12-2 TU12-3
TUG3-1 TUG3-2 TUG3-3
TUG2-6
TUG2-7
TUG2-5
TUG2-4
TUG2-3
TUG2-1
TUG2-2
TUG-3 number (values 1-3)TUG-2 number (values 1-7)TU-12 number (values 1-3)
KLM: 271KLM: 152
VC-3
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Chapter – 1 SDH Theory
STM-N Frame
T1518000-95
4
3
1
9
5
270 × N columns (bytes)
9 × N 261 × N
STM-N payload9 rows
Section overheadSOH
Section overheadSOH
Administrative unit pointer(s)
• One SOH• AU pointers for every VC-4• N × VC-4s
Synchronous TransportModule
Line RateMbit/s
STM-1 155.520
STM-4 622.080
STM-16 2488.320
STM-64 9953.280
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Chapter – 1 SDH Theory
Multiplexing of AU into STM-N
AUG
AUG
AUG
AUG
STM-4
SOH
AU-4
AU-4
AU-4
AU-4
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Chapter – 1 SDH Theory
SDH Layers
PSTN ISDN ATM IP
Lower-Order
Higher-Order
Multiplex
Regenerator
Physical
Client
Server
OS, ES
RS
MS
HOP (VC-4)
LOP (VC-12, VC-3)
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Chapter – 1 SDH Theory
Client
Server
SDH Layers
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Chapter – 1 SDH Theory
R R
LO Path
MS trail MStrail
RStrail
RStrail
RStrail
RStrail
MS trail
TM LO TM LOADM HO DXC LO
HO Path HO Path
SDH Trails 1(2)
• Trail: Route between two Trail Termination Points (TTP) • TTP: Point where signal is terminated• RS trail: Regenerator Section trail (or just RS) is between regenerators• MS trail: Multiplex Section trail (or just MS) is between multiplexers• Path (P): Trail in path layer (HOP or LOP)
RStrail
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Chapter – 1 SDH Theory
SDH Trails 2(2)
HO
LO
MS
RS RS RSRS RS RS RS
MS MS MS MS
HO HO
RS RS RS
MS
HO
LO
RS trail RS trail RS trail RS trail RS trail
MS trail MS trailMS trail
HO path HO path
LO path
LO matrix LO matrix
HO matrix
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Chapter – 1 SDH Theory
• Regenerates the optical signal.
• Terminates RSOH.
REGSTM-N STM-N
Regenerator
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Chapter – 1 SDH Theory
Terminal Multiplexer
TMSTM-N
orPDH
STM-M
• Terminates RSOH and MSOH.
• May terminate HOP and LOP overhead.
• Multiplexes/maps tributary signals.
• Includes timing and management functions.
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Chapter – 1 SDH Theory
STM-N or PDH
STM-MSTM-M
ADM
Add/drop Multiplexer
• Terminates RSOH and MSOH.• May terminate HOP and LOP overhead.• Includes connection function between the two aggregates.• Multiplexes/maps tributary signals.• Includes a connection function for allocation of TUs within the STM
frame. • Includes timing and management functions.
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Chapter – 1 SDH Theory
Cross-connect
• Terminates RSOH and MSOH.• Includes connection function between the aggregates.• Can have tributary ports, for which it may terminate HOP and LOP
overhead.• Includes timing and management functions.
STM-N or PDH
STM-MSTM-M DXC
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Chapter – 1 SDH Theory
STM-16
STM-4
STM-1
STM-16
STM-4
STM-1
SDXC 4/1Example of Cross-connect (XC)
16 x
4 x
1 x
16 x
4 x
1 x
SDH multiplexer
AUG
VC-4
34 (45) Mbit/s2(1.5) Mbit/s
VC-12 VC-3
HOXC
LOXC
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Chapter – 1 SDH Theory
SDH Overhead
• Overheads carry information for monitoring, maintaining and controlling the operation of network.
• Overhead types– POH for end-to-end monitoring of payload signal (VC-12, VC-3 and VC-4)
• Block errors, far end alarms, trace and payload type– SOH is used for monitoring of signal between SDH equipment.
• RSOH: block errors, trace and TMN communication• MSOH: block errors, synchronization, TMN communication and far-end
alarms
POH
RSOH
MSOH
POINTER
9 260
270
3
5
9
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Chapter – 1 SDH Theory
1 2 3 4 5 6 7 8 9RSOH 1 A1 A1 A1 A2 A2 A2 J0 NU1 NU2RSOH 2 B1 R1 R2 E1 R3 U1 F1 NU3 NU4RSOH 3 D1 R4 R5 D2 R6 U2 D3 U3 U4PTR 4 H1 Y1 Y2 H2 1 1 H3 H3 H3
MSOH 5 B2 B2 B2 K1 U5 U6 K2 U7 U8MSOH 6 D4 U9 U10 D5 U11 U12 D6 U13 U14MSOH 7 D7 U15 U16 D8 U17 U18 D9 U19 U20MSOH 8 D10 U21 U22 D11 U23 U24 D12 U25 U26MSOH 9 S1 Z12 Z13 Z21 Z22 M1 E2 NU5 NU6
RSOH
– A1, A2 framing patterns (F6H), (28H)– J0 regenerator section Trail Trace Identifier (TTI)– B1 BIP-8 parity byte– E1 RS orderwire channel (service telephone)– F1 user (network operator) data channel– D1, D2, D3 regenerator section Data Communication Channel (DCCR)– NU1, NU2, NU3, NU4 bytes reserved for national use– R1, R2, R3, R4, R5, R6 media specific bytes (e.g. radio link)– U1, U2, U3, U4 bytes with no defined use
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Chapter – 1 SDH Theory
MSOH
– B2 BIP-24 parity bytes– K1, K2 Automatic Protection Switching (APS) channel, bit oriented
protocol (bits 1-5), Remote Defect Indication (RDI) (bits 6-8)– D4 to D12 multiplex section Data Communication Channel (DCCM)– S1 synchronization status (bits 5-8)– M1 Remote Error Indication (REI)– E2 MS orderwire channel (service telephone)– NU5, NU6 bytes reserved for national use– U5 to U26 bytes with no defined use– Z12, Z13, Z21, Z22 bytes with no defined use
1 2 3 4 5 6 7 8 9RSOH 1 A1 A1 A1 A2 A2 A2 J0 NU1 NU2RSOH 2 B1 R1 R2 E1 R3 U1 F1 NU3 NU4RSOH 3 D1 R4 R5 D2 R6 U2 D3 U3 U4PTR 4 H1 Y1 Y2 H2 1 1 H3 H3 H3
MSOH 5 B2 B2 B2 K1 U5 U6 K2 U7 U8MSOH 6 D4 U9 U10 D5 U11 U12 D6 U13 U14MSOH 7 D7 U15 U16 D8 U17 U18 D9 U19 U20MSOH 8 D10 U21 U22 D11 U23 U24 D12 U25 U26MSOH 9 S1 Z12 Z13 Z21 Z22 M1 E2 NU5 NU6
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Chapter – 1 SDH Theory
VC-4 and VC-3 POH
POHJ1B3C2G1F2H4F3K3N1
REI RDI Reserved Spare
1 2 3 4 5 6 7 8
J1 Trail Trace IdentifierB3 Parity BIP-8C2 Signal label (C2), used for payload type identificationG1 Path status
REI Remote Error IndicationRDI Remote Defect Indication
F2 Network operator (user) channelH4 Multiframe indicator, a sequence indicating TU-multiframe
phase (position of VC-12/VC-2)F3 Network operator (user) channelK3 Automatic Protection Switching (bits 1-4)N1 Tandem Connection Monitoring TCM, optional use in
multioperator environments
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Chapter – 1 SDH Theory
VC-2 and VC-12 POH
J2 Trail Trace IdentifierN2 Tandem Connection Monitoring TCM, optional use in multioperator
environmentsK4 Automatic Protection Switching (bits 1-4), additional
information for RDI (bits 5-7) (optional)V5 Signal monitoring
Parity BIP-2Remote Error Indication (REI)Remote Failure Indication (RFI), only for VC-11 (not in ETSI)Signal label (SL)Remote defect indication (RDI)
POHV5 J2 N2 K4
V51 2 3 4 5 6 7 8BIP-2 BIP-2 REI RFI SL SL SL RDI
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Chapter – 1 SDH Theory
PDH over SDH
2 Mbit/s plesiochronous stream`
Justification bytes
C12POH
Path OverheadVC12
Container
POH
TU PointerTU12
Virtual Container
• Container (C)– basic payload unit
• Virtual Container (VC)– C + POH (path overhead)
• Tributary Unit (TU)– VC + pointer– The pointer indicates the start
of the VC and allows dynamic alignment of the VC within the TU frame.
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Chapter – 1 SDH Theory
Asynchronous Bit synchronous Byte synchronous
PDH signal is notsynchronized with SDH
PDH and SDH aresynchronized but not the
PDH frame (if any)
PDH and SDH aresynchronized and also the
PDH frame
Justification neededaccess to 2048 kbit/s In SONET only Direct access to
64 kbit/s signal
Defined for:139M, 45M, 34M,
6M, 2M, 1.5M
Defined for:6M, 1.5M
Defined for:2M, 31×64 kbit/s, 1.5M
Mapping
• Mapping is a process where tributaries (Containers) are adapted to VC at boundary of SDH network.
• LX: asynchronous
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Chapter – 1 SDH Theory
V5
32 bytes
R R R R R R R RJ2
R R R R R R R R
C1 C2 O O O O R R
32 bytes
R R R R R R R RN2
C1 C2 O O O O R R
32 bytes
R R R R R R R RK4
C1 C2 R R R R R S1S2 D D D D D D D
31 bytes
R R R R R R R R
140octets
11ststfram
efram
e22
ndndframe
frame
33rdrdfram
efram
e44
ththframe
frame
Asynchronous 2048 kbit/s
• Four VC-12 POH bytes(V5, J2, N2 and K4)
• 1023 data bits• Six justification control bits
• C1C1C1=111 ⇒ S1 is a justification bit (data bit)
• C2C2C2=111 ⇒ S2 is a justification bit (data bit)
• Majority vote should be used.• Eight overhead communication channel bits
(0)• 49 fixed stuff bits (R)
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Chapter – 1 SDH Theory
Byte Synchronous 2048 kbit/s
• Four VC-12 POH bytes (V5, J2, N2 and K4)
• No justification opportunities• 2 R-bytes per frame
R
R
R
R
R
V5
R500 µs
R
J2
N2
K4
RTime Slot 0
Time Slots 1 to 15Time Slot 16
Time Slots 17 to 31
Time Slot 0Time Slots 1 to 15
Time Slot 16Time Slots 17 to 31
Time Slot 0Time Slots 1 to 15
Time Slot 16Time Slots 17 to 31
Time Slot 0Time Slots 1 to 15
Time Slot 16Time Slots 17 to 31
140bytes
R Fixed stuff byte
11ststfram
efram
e22
ndndframe
frame
33rdrdfram
efram
e44
ththframe
frame