Optical Transport Network Slide for Optics Begineers

1. OTN NEWBIES
1

2. FOREWORD
 According to the ITU-T Recommendation G.709, an Optical
Transport Network (OTN) is composed of a set of optical
network elements connected by optical fiber links. The network
provides functionality of transport, multiplexing, routing,
management, supervision, and survivability of optical channels
carrying client signals.
 This architecture can be seen as a combination of the
advantages of SDH/SONET technology with the flexibility of
DWDM. Using OTN, the OAM&P functionality of SDH/SONET is
applied to DWDM optical networks.
 Compared to SDH/SONET, OTN has the following advantages:
 • Stronger error correction mechanisms
 • More levels of tandem connection monitoring
 • Transparent transport of client signals
 • Switching scalabilityIntroduction
Page2

3. ABOUT THIS COURSE
 This course is based on the following ITU-T
recommendations:
 ITU-T G.709
 ITU-T G.805
 ITU-T G.806
 ITU-T G.798
Page3

4. LEARNING GUIDE
Just little Basics
4

5. CONTENTS
1. OTN Introduction
2. Typical OTN Scenarios
Page5

6. CONTENTS
1. OTN Introduction
1.1 OTH
1.2 OTN Port Structure
1.3 Multiplexing/Mapping Principles and Bit Rates
1.4 Overhead Description
1.5 Maintenance Signals and Functions of Different
Layers
1.6 Alarms and Performance Events
Page6

7. OTN
 Optical transport network (OTN)
 An OTN network is composed of a set of optical
NEs connected by optical fiber links. These NEs
are able to provide functions such as transport,
multiplexing, routing, management, supervision,
and protection (survivability) of client signals,
according to the requirements specified in REC.
G.872.
Page7

8. FEATURES OF OTN
 Compared with SDH and SONET networks, an OTN
network has the following features:
 Ultra capacity with high accuracy, T-bit/second per fiber over
DWDM lines
 Service transparency for client signals
 Asynchronous mapping, powerful FEC function, simplified
network design, and reduced costs
 Compared with traditional WDM networks, an OTN
network has the following features:
 Enhanced OAM and networking capabilities for all services
 Dynamic electrical/optical-layer grooming
Page8

9. OTN STANDARD SYSTEM
Structure
OTN
OTN network structureG.872
ASON network structureG.8080
Structure and
mapping
Generic frame protocol (GFP)G.7041
Link capacity adjustment
scheme (LCAS) for virtual concatenation signalsG.7042
Ports on an OTN networkG.709
Equipment
functions
and
features
Features of function blocks of equipment on an OTN networkG.798
Transport network equipment features: description methods and general functionsG.806
Physical-layer
features
Optical ports for intra-office systemsG.693
Optical security rule and requirements in an optical transport systemG.664
Physical-layer ports on an OTN networkG.959.1
Network
protection
Linear protection on an OTN networkG.873.1
Ring protection on an OTN networkG.873.2
Jitter and
performance
Jitter and shift control on an OTN networkG.8251
Bit error performance parameters and specifications on
international channels of multiple carriers on an OTN networkG.8201
Equipment
management
Management features of NEs on an OTN networkG.874
OTN network: Protocol-neutral management
information model for the network elementG.874.1
9

10. OTN NETWORK LAYERS AND PORT STRUCTURE
 OPUk: optical channel payload unit-k
 ODUk: optical channel data unit-k
 OTUk: completely standardized optical
channel transport unit-k
 OTUkV: functionally standardized Optical
channel transport unit-k
 OCh: optical channel with full
functionality
 OChr: optical channel with reduced
functionality
 OMS: optical multiplex section
 OTS: optical transmission section
 OPS: optical physical section
 OTM: optical transport module
Page10
ODUk (ODUkP and ODUkT)
OPUk
OTUk OTUkV OTUk OTUkV
OCh OChr
OMSn
OTSn
OPSn
IP/MPLS ATM Ethernet STM-N
OTM-0.m
OTM-nr.m
OTM-n.m

11. OTM-N.M CONTAINMENT RELATIONSHIPS
 “n” represents the maximum number of wavelengths that can be supported at the lowest bit rate
supported by the wavelengths. “m” equals 1, 2, 3, 12, 23, or 123.
 OTS_OH, OMS_OH, OCh_OH and COMMS OH information fields are contained in the OOS.
 The optical supervisory channel (OSC) is used to transmit OOSs.
Page11
OCCp OCCp OCCp
OCh payload
ODUk FECOH
OPUkOH
Client signal
OPUk payloadOHOPUk
ODUk
OTUk[V]
OCh
OCG-n.m
OTM-n.m OTSn OH
OMSn OH
OCCo
OChOH
OCCo
OCCo
OMU-n.m
Non-associatedOH
OOS
Common
management
OH
OTM-n.m
OTM overhead signal (OOS)
l 2
l 1
l n
l OSC

12. OTM-NR.M CONTAINMENT RELATIONSHIPS
 Fixed channel spacing, irrelevant to the signal rate
 1 < n ≤ 16; m = 1, 2, 3, 12, 23, or 123
 Without optical supervisory channels
Page12
OCCp OCCp OCCp
OCh payload
ODUk FECOH
OPUkOH
Client signal
OPUk payloadOHOPUk
ODUk
OTUk[V]
OChr
OCG-nr.m
OTM-nr.m
OTM-16r.m
l 2
l 1
l 16

13. OTM-0.M CONTAINMENT RELATIONSHIPS
 The OTM 0.m supports a non-colored optical channel on a single optical span with 3R
regeneration at each end.
 m = 1, 2, or 3
 Without optical supervisory channels
Page13
OCh payload
ODUk FECOH
OPUkOH
Client signal
OPUk payloadOHOPUk
ODUk
OTUk[V]
OChr
OTM-0.m OPS0
OTM-0.m

14. OTN PORTS
 User to network interface (UNI)
 Network node interface (NNI)
 Inter-domain interface (IrDI)
 Intra-domain interface (IaDI)
 Between equipment provided by different vendors (IrVI)
 Within subnet of one vendor (IaVI)
 The completely standardized OTUk is used at OTM IrDIs and OTM IaDIs.
 The partly standardized OTUk is used at OTM IaDIs.
Page14
OTM
UNI
OTM NNI
IaDI-IrVI
OTM NNI
IaDI-IaVI
OTM NNI
IaDI-IaVI
Network Operator B
Vendors X Vendors Y
OTM
NNI
IrDI
Network
Operator
C
USER
A

15. CONTENTS
1. OTN introduction
1.1 Optical transport hierarchy
1.2 OTN interface structure
1.3 Multiplexing/mapping principles and bit rates
1.4 Overhead description
1.5 Maintenance signals and function for different
layers
1.6 Alarm and performance events
Page15

16. OTN MULTIPLEXING AND MAPPING STRUCTURE
Page16
Mapping
Multiplexing
ODTUG3
ODTUG2
OChr
OChr
OChr
OCh
OCh
OCh
OTU3[V]
OTU2[V]
OTU1[V]
Client signal
Client signal
OPU3ODU3
OCCr
OCCr
OCCr
OCC
OCC
OCC
OCG-nr.m
1 ≤ i+j+k ≤ n
OCG-n.m
1 ≤ i+j+k ≤ n
OPU2ODU2
1
OPU1ODU1
OTM-nr.m
OTS, OMS, OCh, COMMSOSC OOS
OTM-n.m
4
1
14
161
11
1
1
1
1
1
1
1
1
1
1
1
1
1
1
 i
 j
 k
 i
 j
 1
Clientsignal
1
OTM-0.m
 k

17. OTN Multiplexing and Mapping Structure
17

18. OTN Multiplexing and Mapping Structure
18

19. OPUflex
OPU4
OPU3
OPU2
OPU0
OPU1
Client service rate
1.238G
2.488G
9.995G
40.149G
104.134G
10.312G OPU2e
LO OPU
OPUflex(GFP)
OPUflexOPUflex
 LO ODU
 New LO ODU signals
 1.25G ODU0
 10.3G ODU2e
 104G ODU4
 ODUflex
OTN Service Bearing Capability (LO ODU)
19

20. OTN LINE BEARING CAPABILITY
(HO ODU)
OPU3e2/21
(ODU0,ODU1,ODU2,ODU2e,ODUflex)
OPU3/20
(ODU1,ODU2)
OPU2/21
(ODU0,ODU1,ODUflex)
OPU2/20
(ODU1)
OPU4/21
(ODU0,ODU1,ODU2,ODU2e,ODU3,ODU3e2,ODUflex)
OPU3/21
(ODU0,ODU1,ODU2,ODU2e,ODUflex)
OPU1
(ODU0)
LO ODU rate
ODU0
ODU1
ODU2
ODU3
ODU4
ODU2e
HO OPU
ODUflexODUflexODUflex
ODUflex(GFP)
ODU3e2
 New HO ODU signals
 2.5G ODU1
 41.7GG ODU3e2 (G.sup43)
 104G ODU4
 Signals with extended
capabilities
– 10G ODU2
– 40G ODU3
20

21. OTUK FRAME RATE
OTU Type OTU Nominal Bit Rate OTU Bit Rate Tolerance
OTU1 255/238 x 2488320 kbit/s
20 ppm
OTU2 255/237 x 9953280 kbit/s
OTU3 255/236 x 39813120 kbit/s
OTU4 255/227 x 99532800 kbit/s
Note 1: The nominal OTUk rates are approximately 2666057.143 kbit/s (OTU1), 10709225.316
kbit/s (OTU2), 43018413.559 kbit/s (OTU3) and 111809 973.568 kbit/s (OTU4).
Note 2: OTU0, OTU2e and OTUflex are not specified in this recommendation. ODU0 signals
are transported over ODU1, ODU2, ODU3 or ODU4 signals, ODU2e signals are transported
over ODU3 and ODU4 signals, and ODUflex signals are transported over ODU2, ODU3 and
ODU4 signals.
OTUk rate = 255/(239 - k) x STM-N frame rate

22. ODUK FRAME RATE
ODU Type ODU Nominal Bit Rate ODU Bit Rate Tolerance
ODU0 1244160 kbit/s
20 ppm
ODU1 239/238 x 2488320 kbit/s
ODU2 239/237 x 9953280 kbit/s
ODU3 239/236 x 39813120 kbit/s
ODU4 239/227 x 99532800 kbit/s
ODU2e 239/237 x 10312500 kbit/s
100 ppm
ODUflex for CBR
client signals
239/238 x Client signal bit rate
Client signal bit rate tolerance, with a
maximum of 100 ppm
ODUflex for GFP-F
mapped client
signals
Pre-set bit rate 20 ppm
ODUk rate = 239/(239 - k) x STM-N frame rate

23. OPUK FRAME RATE
OPU Type OPU Payload Nominal Bit Rate OPU Payload Bit Rate Tolerance
OPU0 238/239 x 1244160 kbit/s
20 ppm
OPU1 2488320 kbit/s
OPU2 238/237 x 9953280 kbit/s
OPU3 238/236 x 39813120 kbit/s
OPU4 238/227 x 99532800 kbit/s
OPU2e 238/237 x 10312500 kbit/s
100 ppm
OPUflex for CBR client
signals
Client signal bit rate
Client signal bit rate tolerance, with a
maximum of 100 ppm
OPUflex for GFP-F
mapped client signals
238/239 x ODUflex signal rate 20 ppm
OPU1-Xv X x 2 488 320 kbit/s
20 ppm
OPU2-Xv X x 238/237 x 9953280 kbit/s
OPUk payload rate = 238/(239 - k) x STM-N frame rate

24. ODUK (TDM)
 Low-rate ODUk signals are multiplexed into high-
rate ODUk signals using time-division multiplexing:
 A maximum of four ODU1 signals are multiplexed into
one ODU2 signal using time-division multiplexing.
 Hybrid j (j  4) ODU2 and 16-4j ODU1 signals are
multiplexed into one ODU3 signal using time-division
multiplexing.
 Multiple LO ODUi[j] signals at different levels are
multiplexed into one HO ODUk signal.
Page24

25. ODU1 MULTIPLEXED INTO ODU2
 ODTU12: optical channel data tributary unit 1 into 2
 ODTUG2: optical channel data tributary unit group 2
 JOH: justification overhead
Page25
ODU1
OH ODU1ODU1 payload
ODTU12
JOH
ODU1 ODTU12
ODU2
OH
OPU2
OH
ODU2 payload
OPU2
ODU2
ODTU12
JOH
ODU1
ODTU12
JOH
ODU1 ODTUG2
ODTUG2
OPU2 payload

26. ODU1 MULTIPLEXED INTO ODU2
 ODU1 floats in one quarter of the OPU2 payload area.
 An ODU1 frame travels cross multiple ODU2 frame boundaries.
Page26
OTU2 OTU2
FEC
Client-layer signal
(STM-16, ATM, or GFP)
ODU1
ODU1OH
Alignment
ODU2
x4
Client Layer Signal
(for example, STM-16)ODU1 OH
OPU1OH
Client Layer Signal
(for example, STM-16)ODU1 OH
OPU1OH
Client Layer Signal
(for example, STM-16)ODU1 OH
OPU1OH
Client-layer signal
(STM-16, ATM, or GFP)ODU1 OHODU2 OH
OPU2OH
OPU2 Payload
ODU2 OH
Alignment
OPU2OH
OTU2
OH
Client Layer Signal
(for example, STM-16)ODU1 OH
OPU1OH
Client Layer Signal
(for example, STM-16)ODU1 OH
OPU1OH
Client Layer Signal
(for example, STM-16)ODU1 OH
OPU1OH
Client-layer signal
(STM-16, ATM, or GFP)ODU1 OH
OPU1OH
Alignment
Alignment
OPU1OH
OPU1OH

27. ODU1 AND ODU2 MULTIPLEXED INTO ODU3
 ODTU23: optical channel data tributary unit 2 into 3
 ODTU13: optical channel data tributary unit 1 into 3
Page27
ODU1
OH ODU1ODU1 payload
ODTU13
JOH
ODU1 ODTU13
ODU3
OH
OPU3
OH
ODU3 payload
OPU3
ODU3
ODTU23
JOH
ODTU23
JOH
ODU1 ODTUG3
ODTUG3
OPU3 payload
ODU2
OH ODU2ODU2 payload
ODTU23
JOH
ODU2 ODTU23
ODTU13
JOH
ODU2ODTU13
JOH
ODU2 ODU1

28. OH
Payload Area
client data
stuff
server frame or multi-frame
0
memory
Pserver?
Pserver
client
data
indication
=
read/write
enable
payload area
frame start
clock
Cm(t)
enable
 GMP can automatically adapt CBR services to an OTN container. It is the key
technology for an OTN network to bear multiple services.
 Service rate information transmitted in overheads
 Sigma-delta algorithm
 M byte bit width
 Separation of data and clocks
GMP Mapping
28

29. ODUflex
OH
OH
Services with
a fixed bit rate
Client signals
Packet services
Client services
OH
GMP
TSi TSj
ODUflex
OH
BMP
TSi TSj
GMP
GFP
 Map CBR services to ODUflex services using synchronized packet encapsulation.
 Map packet services to ODUflex services using GFP.
 Map ODUflex services to HO OPUk services using GMP.
ODUflex
29

30. CONTENTS
1. OTN introduction
1.1 Optical transport hierarchy
1.2 OTN interface structure
1.3 Multiplexing/mapping principles and bit rates
1.4 Overhead description
1.5 Maintenance signals and function for different
layers
1.6 Alarm and performance events
Page30

31. OOS
 TTI: trail trace identifier
 PMI: payload missing indication
 OCI: open connection indication
 BDI-O: backward defect indication - overhead
 BDI-P: backward defect indication - payload
 FDI-O: forward defect indication - overhead
 FDI-P: forward defect indication - payload
Page31
Non-associated
overhead
OTSn
n
3
2
OCh
1
General management communication
OMSn
FDI-O
FDI-P
OCI
BDI-O
BDI-P
PMI
FDI-P
FDI-O
BDI-O
BDI-P
PMI
TTI
OOS functions subject to
standardization. Bit rate
and format are not
standardized.

32. OPTICAL-LAYER FUNCTION
Page32
OTSn
BDI-O
BDI-P
PMI
TTI MI_TxTI
aPMI
RI_BDI-P
RI_BDI-O
PayloadOTSn OH
dLOS_P
Payload and OH combined together APR control
OA, DCM
 The OTS source function is used as an example.

33. Page33
OTN FRAME FORMATS (K = 1, 2, OR 3)
3825
4080
1
7
8
14
15
16
17
3824
1
2
3
4
OPU k payloadOPUkOH
OPUk - optical channel payload unit
ODUk
OH
ODUk - Optical Channel Data Unit
Client signal
mapped in
OPUk payload
Client signal
OTUK
FEC
OTUk
OH
OTUk - Optical Channel Transport Unit
Alignment
Alignment
K:
1 - 2.5G
2 - 10G
3 - 40G
33

34. OTN ELECTRICAL OVERHEAD OVERVIEW
Page34
 ODUk OH
 TCMACT: tandem connection monitoring
activation/deactivation control channel
 TCMi: tandem connection monitoring i
 FTFL: fault type and fault location reporting
channel
 PM: path monitoring
 EXP: experimental
 GCC1/2: general communication channel 1/2
 APS/PCC: automatic protection switching
coordination channel/protection
communication control channel
 Alignment OH
 FAS: frame alignment signal
 MFAS: multiframe alignment signal
 OTUk OH
 SM: section monitoring
 GCC0: general communication channel 0
 RES: reserved for future international
standardization
OPUk OH
 PSI: payload structure identifier
 JC: justification control
 NJO: negative justification opportunity
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2 TCM1
TCM4
PM
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS MFAS SM GCC0 RES JCRES
17

35. FRAME ALIGNMENT SIGNAL
Page35
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8
OA1 OA1 OA1 OA2 OA2 OA2
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2 TCM1
TCM4
PM
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS MFAS SM GCC0 RES JCRES
17
 Frame alignment signal (FAS)
 A six-byte OTUk-FAS signal is defined in row 1 and columns 1 to 6 of the
OTUk overhead.
 OA1 is 0xF6 (1111 0110) and OA2 is 0x28 (0010 1000).

36. MULTIFRAME ALIGNMENT SIGNAL
Page36
MFAS OH byte
MFASsequence
1 2 3 4 5 6 7 8
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 1
0 0 0 0 0 0 1 0
0 0 0 0 0 0 1 1
0 0 0 0 0 1 0 0
....
.
.
1 1 1 1 1 1 1 0
1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 1
..
 Multiframe alignment signal (MFAS)
 It is defined in row 1 and column 7.
 The value of the MFAS byte is increased by OTUk/ODUk
frame and the MFAS byte provides a maximum of 256
multiframes.
 Individual OTUk/ODUk overhead signals may use this
central multiframe to lock their 2, 4, 8, 16, or 32
multiframes to the main frame.
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2 TCM1
TCM4
PM
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS SM GCC0 RES JCRES
17
MFAS

37. OTUK SECTION MONITORING OVERHEAD
Page37
 Trail trace identifier (TTI)
 A one-byte overhead is defined to transport 64-byte TTI
signals.
 The 64-byte TTI signal should be aligned with the OTUk
multiframe and transmitted four times per multiframe.
 TTI structure:
 16-byte SAPI: source access point identifier
 16-byte DAPI: destination access point identifier
 32-byte operator specified information
Operator
specified
TTI BIP-8
BEI/BIAE
BDI
RES
1 2 3 4 5 6 7 8
1 2 3
IAE
63
32
0
15
16
31
SAPI
DAPI
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2 TCM1
TCM4
PM
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS GCC0 RES JCRES
17
MFAS SM

38. OTUK SECTION MONITORING OVERHEAD
 Bit interleaved parity-8 (BIP-8)
 For section monitoring and a one-byte error detection code signals are defined.
 This byte provides a bit interleaved parity-8 (BIP-8) code.
 OTUk BIP-8 is computed over bits in the OPUk (columns 15 to 3824) area of OTUk frame
i, and inserted in the OTUk BIP-8 overhead location in OTUk frame i+2.
Page38
BIP8
OPUk
1 14 15 3824
Frame i
Frame i+1
Frame i+2

39. OTUK SECTION MONITORING OVERHEAD
 Backward error indication/backward incoming
alignment error (BEI/BIAE)
 A four-bit BEI and BIAE signal is defined.
 This signal is used to transmit in the upstream direction
the count of interleaved-bit blocks and incoming
alignment error (IAE) conditions.
 During an IAE condition the code "1011" is inserted into
the BEI/BIAE field and the error count is ignored.
Otherwise the error count (0-8) is inserted into the
BEI/BIAE field.
Page39
Operator
specified
TTI BIP-8
BEI/BIAE
BDI
RES
1 2 3 4 5 6 7 8
1 2 3
IAE
63
32
0
15
16
31
SAPI
DAPI
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2 TCM1
TCM4
PM
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS GCC0 RES JCRESMFAS SM

40. OTUK SECTION MONITORING OVERHEAD
 Backward defect indication (BDI)
 A single-bit BDI signal is defined to transmit the
signal failure status detected by the section
termination sink function in the upstream direction.
 BDI is set to "1" to indicate an OTUk backward
defect indication; otherwise, it is set to "0".
Page40
Operator
specified
TTI BIP-8
BEI/BIAE
BDI
RES
1 2 3 4 5 6 7 8
1 2 3 IAE
63
32
0
15
16
31
SAPI
DAPI
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2 TCM1
TCM4
PM
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS GCC0 RES JCRES
17
MFAS SM

41. OTUK SECTION MONITORING OVERHEAD
 Incoming alignment error (IAE)
 A single-bit IAE signal is defined to allow the S-CMEP
ingress point to inform its peer S-CMEP egress point
that an alignment error in the incoming signal has
been detected.
 IAE is set to "1" to indicate a frame alignment error;
otherwise it is set to "0".
 RES (reserved)
 Two bits are reserved (RES) for future international
standardization. They are set to "00".
Page41
Operator
specified
TTI BIP-8
BEI/BIAE
BDI
RES
1 2 3 4 5 6 7 8
1 2 3
IAE
63
32
0
15
16
31
SAPI
DAPI
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2 TCM1
TCM4
PM
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS GCC0 RES JCRES
17
MFAS SM

42. OTUK GCC0 AND RES OVERHEAD
 General communication channel (GCC0)
 Two bytes are allocated in the OTUk overhead to support a general
communications channel between OTUk termination points.
 A clear channel is located in row 1 and columns 11 and 12.
 RES (reserved)
 Two bytes of the OTUk overhead are reserved for future international
standardization.
 They are located in row 1 and columns 13 and 14.
 They are set to all “0”s.
Page42
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2 TCM1
TCM4
PM
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS RES JCRES
17
MFAS SM GCC0

43. ODUK PATH MONITORING OVERHEAD
Page43
 TTI / BIP-8 / BEI / BDI
 For path monitoring, this overhead’s functions are the
same as those of the OTUk SM signal, except that BEI
signals do not support the BIAE function.
 They are located in row 3 and columns 10 to 12.
Operator
specified
TTI BIP-8
BEI
BDI
STAT
1 2 3 4 5 6 7 8
1 2 3
63
32
0
15
16
31
SAPI
DAPI
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2 TCM1
TCM4TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS RES JCRES
17
MFAS SM GCC0
PM

44. ODUK PATH MONITORING OVERHEAD
Page44
Operator
specified
TTI BIP-8
BEI
BDI
STAT
1 2 3 4 5 6 7 8
1 2 3
63
32
0
15
16
31
SAPI
DAPI
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2 TCM1
TCM4TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS RES JCRES
17
MFAS SM GCC0
PM
Bit 678 Status
000 Reserved for future international standardization
001 Normal path signal
010 Reserved for future international standardization
011 Reserved for future international standardization
100 Reserved for future international standardization
101 Maintenance signal: ODUk - LCK
 Status (STAT)
 For path monitoring, three bits are defined as status bits.
 They indicate the presence of a maintenance signal.

45. ODUK TCM OVERHEAD
Page45
 TTIi/BIP-8i/BEIi/BIAEi/BDIi
 For each tandem connection monitoring field,
this overhead’s functions are the same as
those of OTUk SM signals.
 Six fields of the ODUk TCM overhead are
defined in row 2 and columns 5 to 13, and row
3 and columns 1 to 9 of the ODUk overhead.
TTIi BIP-8i
BEIi/BIAEi
BDIi
STATi
1 2 3 4 5 6 7 8
1 2 3
63
32
0
15
16
31
SAPI
DAPI
Operator
specific
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS RES JCRESMFAS SM GCC0
PMTCM1TCM2TCM3
TCM6 TCM5 TCM4

46. ODUK TCM OVERHEAD
Page46
TTIi BIP-8i
BEIi/BIAEi
BDIi
STATi
1 2 3 4 5 6 7 8
1 2 3
63
32
0
15
16
31
SAPI
DAPI
Operator
specified
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIGCC2 APS/PCC RES
EXP
FAS RES JCRES
17
MFAS SM GCC0
PMTCM1
Bit 678 Status
000 No source TC
001 In use without IAE
010 In use without IAE
011 Reserved for future international standardization
100 Reserved for future international standardization
101 Maintenance signal: ODUk -LCK
110 Maintenance signal: ODUk -OCI
TCM2TCM3
TCM6 TCM5 TCM4
 STAT (status)
 For each tandem connection monitoring field, three
bits are defined as status bits.
 They indicate the presence of a maintenance signal if
there is an incoming alignment error at the source
TC-CMEP, or if there is no source TC-CMEP active.

47. NESTED AND CASCADED ODUK MONITORED
CONNECTIONS
Page47
A1 B1 C1 C2 B2 B3 B4 A2
A1 - A2
B1 - B2
C1 - C2
B3 - B4
TCM1 TCM1
TCM2
TCM1
TCM2
TCM3
TCM1
TCM2
TCM1 TCM1
TCM2
TCM1
TCM2
TCM3
TCM4
TCM5
TCM6
TCMi TCM OH field not in use TCMi TCM OH field in use
TCM2
TCM3
TCM4
TCM5
TCM6
TCM2
TCM3
TCM4
TCM5
TCM6
TCM3
TCM4
TCM5
TCM6
TCM3
TCM4
TCM5
TCM6
TCM3
TCM4
TCM5
TCM6
TCM4
TCM5
TCM6

48. OVERLAPPED ODUK MONITORED CONNECTIONS
Page48
A1 B1 C1 C2B2 A2
A1 - A2
B1 - B2
C1 - C2
TCM1 TCM1
TCM2
TCM1
TCM2
TCM3
TCM1
TCM2
TCM1
TCMi TCM OH field not in use TCMi TCM OH field in use
TCM2
TCM3
TCM4
TCM5
TCM6
TCM2
TCM3
TCM4
TCM5
TCM6
TCM3
TCM4
TCM5
TCM6
TCM3
TCM4
TCM5
TCM6
TCM4
TCM5
TCM6

49. ODUK TCM ACT COORDINATION PROTOCOL
Page49
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2
TCM4
TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIAPS/PCC RES
EXP
FAS RES JCRES
17
MFAS SM GCC0
PMTCM1
GCC2
 TCM activation/deactivation (TCMACT)
 A one-byte TCM activation/deactivation field is located in row 2 and
column 4.
 Its definition is to be defined in future.

50. ODUK GCC1/GCC2
Page50
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2
TCM4TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIAPS/PCC RES
EXP
FAS RES JCRES
17
MFAS SM GCC0
PMTCM1
GCC2
 General communication channel (GCC1/GCC2)
 Two fields of the two bytes are allocated in the ODUk overhead to support two
general communication channels between any two NEs with access to the ODUk
frame structure (for example, at 3R regeneration points).
 The bytes for GCC1 are located in row 4 and columns 1 and 2, and the bytes for
GCC2 are located in row 4 and columns 3 and 4 of the ODUk overhead.

51. ODUK APS/PCC CHANNEL
Page51
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2
TCM4TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIRES
EXP
FAS RES JCRES
17
MFAS SM GCC0
PMTCM1
GCC2 APS/PCC
 Automatic protection switching/protection communication control
(APS/PCC)
 A four-byte ODUk-APS/PCC signal is defined in row 4 and columns 5 to 8 of the ODUk
overhead.
 For linear protection schemes, bit assignments for these bytes and the bit oriented
protocol are given in ITU-T G.873.1. Bit assignment and byte oriented protocol for ring
protection schemes are to be defined in future.
 A maximum of eight levels of nested APS/PCC signals may be present in this field.

52. ODUK FTFL CHANNEL
 Fault Type & Fault Location (FTFL)
 One byte is allocated in the ODUk overhead to transport a 256-byte FTFL
message.
 The byte is located in row 2 and column 14 of the ODUk overhead.
 The 256-byte FTFL message consists of two 128-byte fields. The forward field is
allocated in bytes 0 to 127 of the FTFL message. The backward field is allocated
in bytes 128 to 255 of the FTFL message.
Page52
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2
TCM4TCM
ACT
GCC1
RES JC
RES JC
NJOPSIAPS/PCC RES
EXP
FAS RES JCRES
17
MFAS SM GCC0
PMTCM1
GCC2
FTFL

53. ODUK EXPERIMENTAL AND RESERVED OVERHEAD
 Experimental (EXP)
 Two bytes are allocated in the ODUk overhead for experimental use.
 They are located in row 3 and columns 13 and 14 of the ODUk overhead.
 There is no requirement for forwarding the EXP overhead over different (sub)networks.
 RES
 9 bytes are reserved in the ODUk overhead for future international standardization.
 They are located in row 2 and columns 1 to 3, and row 4 and columns 9 to 14 of the ODUk
overhead.
 They are set to all “0”s.
Page53
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2
TCM4TCM
ACT
GCC1
FTFL RES JC
RES JC
NJOPSIAPS/PCC
FAS RES JCRES
17
MFAS SM GCC0
PMTCM1
GCC2
EXP
RES
RES

54. OPUK PAYLOAD STRUCTURE IDENTIFIER
 Payload structure identifier (PSI)
 One byte is allocated in the OPUk overhead
to transport a 256-byte payload structure
identifier (PSI) signal.
 It is aligned with the ODUk multiframe.
 PSI[0] contains a one-byte payload type.
PSI[1] to PSI[255] are mapping and
concatenation specific.
Page54
255
0
1
PT
Mapping
and concatenation
specific
RES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
2
3
4
TCM3
TCM6 TCM5
TCM2
TCM4TCM
ACT
GCC1
RES JC
RES JC
NJOAPS/PCC RES
EXP
FAS RES JCRES
17
MFAS SM GCC0
PMTCM1
GCC2
FTFL
PSI

55. PAYLOAD TYPE CODE POINTS
MSB 1234 LSB 1234 Hex Code
Meaning
0000 0001 01 Experimental mapping
0000 0010 02 Asynchronous CBR mapping
0000 0011 03 Bit synchronous CBR mapping
0000 0100 04 ATM mapping
0000 0101 05 GFP mapping
0000 0110 06 Virtual Concatenated signal
0001 0000 10 Bit stream with octet timing mapping
0001 0001 11 Bit stream without octet timing mapping
0010 0000 20 ODU multiplex structure
0101 0101 55 Not available
0110 0110 66 Not available
1000 xxxx 80-8F Reserved codes for proprietary use
1111 1101 FD NULL test signal mapping
1111 1110 FE PRBS test signal mapping
1111 1111 FF Not availablePage55

56. OPUK MAPPING SPECIFIC OVERHEAD
 Justification control/negative justification opportunity/reserved
(JC/NJO/RES)
 Seven bytes are reserved in the OPUk overhead for the mapping and concatenation
specific overhead.
 These bytes are located in rows 1 to 3 and columns 15 and 16, and row 4 and column
16.
 255 bytes in the PSI are reserved for mapping and concatenation specific purposes.
Page56
RES
1
2
3
4
TCM3
TCM6 TCM5
TCM2
TCM4TCM
ACT
GCC1
RES JC
JC
APS/PCC RES
EXP
FAS RES JCRESMFAS SM GCC0
PMTCM1
GCC2 PSI
FTFL
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
RES
NJO

57. THANKS FOR BEING PATIENT
57