OTN networks provide transparent transport of client signals while protecting client management information and enabling low latency transport through enhanced fault detection and correction capabilities. Ciena enhances OTN with support for low-rate client interfaces, sub-wavelength grooming to improve efficiency, and intelligent control plane automation. The Optical Transport Network defined in ITU G.709 standards allows convergence of networks through transport of legacy and future client protocols with flexibility.

1. OTN Networks
OTN advantages
» Transparency for native transport of client signals protecting client-generated management information in the overhead
» Low overhead for efficient transport and reduced latency
» Enhanced maintenance capability for signals traversing through multi-operator networks
» Forward Error Correction (FEC) for improving long distance transport
Ciena’s OTN Enhancements
» Low-rate client interface support and aggregation into OTU1 payloads
» Transparent sub-wavelength grooming for efficient capacity utilization improving network throughput
» OTU2(e,f) line rates for transparent transport of 10 Gb/s Ethernet and high-speed Fiber Channel (FC)
» Intelligent Control Plane enables automated mesh connectivity and 50ms mesh restoration between Ethernet, OTN, SONET and SDH
networks
The Optical Transport Network (OTN) defined in ITU G.709, allows network operators to converge networks through seamless
transport of the numerous types of legacy protocols while providing the flexibility required to support future client protocols.
1
1
3
4
TCM enables signal management across
multiple networks.
The ODU allows the user to support Path Monitoring (PM),
Tandem Connection Monitoring (TCM) and
Automatic Protection Switching (APS).
Fault Type and Fault
Location channel (FTFL)
A 256 byte multi-frame
signal providing fault
status information
regarding type and
location of the fault.
Access Point Identifier (API) structure
CC Country Code
ICC ITU Carrier Code
IS International Segment
NS National Segment
UAPC Unique Access Point Code
TCMi/PM
Operator Identifier Field Structure
G/PCC Geographic/Political country code
Fault indication codes
ODUk TCM status interpretation
TCM byte 3, Status
bits 678
000_________ no source TC
001_________ in use without IAE
010_________ in use with IAE
011_________ reserved for future
international standardization
100_________ reserved for future
international standardization
101_________ mainentance signal: ODUk-LCK
110_________ mainentance signal: ODUk-OCI
111_________ mainentance signal: ODUk-AIS
ODUk PM status interpretation
PM byte 3, Status
bits 678
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_________ mainentance signal: ODUk-LCK
110_________ mainentance signal: ODUk-OCI
111_________ mainentance signal: ODUk-AIS
PM enables the monitoring of particular sections
within the network and fault location.
11 2
2 RES
ROW#ForwardDirection
API
BackwardDirection
COLUMN#
TCM3 TCM2
TCM6 TCM5 TCM4 FTFL
TCM1 PM EXP
TCM
ACT
GCC1 GCC2 APS/PCC RES
3
3
4
0
1
9
10
127
128
129
137 0000 0001
138
255
4
5 6 7 8 9 10 11 12 13 14
FAULT INDICATION FIELD
OPERATOR IDENTIFIER
FIELD
FAULT INDICATION FIELD
OPERATOR IDENTIFIER
FIELD
OPERATOR SPECIFIC
FIELD
OPERATOR SPECIFIC
FIELD
129 130 131 132 133 134 135 136 137
1 2 3 4 5 6 7 8 9
Fault
indication
code
Definition
No fault0000 0000
0000 0001 Signal fail
Signal degrade0000 0010
Reserved for future
international
standardization
0000 0011.
.
.
1111 1111
Country code National segment code
Null Padding
Null Padding
Null Padding
Null Padding
Null
Padding
G/PCC
G/PCC
G/PCC
G/PCC
G/PCC
G/PCC
NULL
ICC
ICC
ICC
ICC
ICC
ICC
1
0
1
15
16
31
32
63
1 2 3 4 5 6 7 8
1
1 2
CC ICC
ICC
ICC
ICC
UAPC
UAPC
UAPC
UAPC
CC
CC
CC
3 4 5 6 7 8 9 10 11 12 13 14 15
2 3 4 5 6 7 8
2
TTIi
0x00
0x00
SAPI
DAPI
Operator
Specific
BIP-8i
TCM
PM
BEIi/BIAEi BDIi STATi
BEI BDI STAT
3
OTUk TCMi & PM
BEI/BIAE bits 1234
Interpretation
0…8 BIP error
IS Character # NS Character #
9…15
11 (N/A for PM)
No BIP error
BIAE, no BIP error
ICC UAPCCC
ICC UAPCCC
Optical Channel Data Unit (ODU)
Container
Type
Client SignalLine Rate
(Gbps)
Payload
Rate (Gbps)
Frame Period
(µs)
OTU1
OTU2
OTU2e
OTU3
2.6661
10.709
11.049 10.3125 11.816
43.018
2.48832
9.9953
40.151
48.971
12.191
3.035
OC-48/STM-16
ITU G.709 OTN
Standard Bit Rates
*OPVC payload container. OPVCs can be concatenated in 155.52 Mb/s containers.
OTN Extensions
OTU1
Channelized*
2.6661 N x 0.15552 3134.2* OC-3/STM-1, ESCON®
, FC100/200,
10/100/1000 Base-T, GbE
OC-192/STM-64,10GbE WAN,
10GbE LAN PHY (MAC Frames)
10GbE
(Transparent)
OTU2f 11.270 10.51875 11.585
10G FC
(Transparent)
OC-768/STM-256
OTU Bit Rate Capacity
OTN Layers
ODU and OPVC
OCh and OTU
OADMOLA OLA MSTPMSTP
OMS
OTS OTS OTS OTS
OMS
OTS monitors optical span connections between NEs
OMS monitors connections between NEs with optical multiplex functions (OADMs)
OCh transports client signals between 3R regeneration points
OTU monitors electrical span connections between MSTPs
ODU monitors end-to-end client paths for wavelength services
OPVC monitors end-to-end client paths for sub-wavelength services
OADM OADM
Optical Transport Module (OTM)
The OTM is the information structure that is transported across the OTN node interface
OOS
Optical Transmission Section (OTS)
Optical Multiplex Section (OMS)
OCC
OTU
OH
ODU
OH
OPU
OH
FEC
OCC OCC OCC
OTU Payload
OCh
ODU Payload
OPU Payload
OPVC
OH OPVC Payload (Ciena)
Low-speed SONET/SDH, GFP, Ethernet
FC100/200, ESCON, Video, Other
Client
SONET/SDH, ATM, Ethernet, Other
OCh
OH
OTS
OH
OMS
OH
O
C
C
o
O
C
C
o
O
C
C
o
The OPU OH supports the mapping and concatenation of the client signals and provides information on the type of signal transported.
Payload Structure Identifier (PSI)
A 256 byte multi-frame signal.
The PSI[0] contains the Payload Type (PT)
Justification Bits (NJO, PJO)
Required for asynchromous mappings.
For synchronous mappings all JCs are
0 and the PJO is a data byte.
Mapping and Concatenation
PSI[1] to PSI[255] are mapping and
concatenation specific.
JC, NJO and PJO generation by asynchronous mapping process
Payload type code points
Hex code Interpretation
01 ______ Experimental mapping
02 ______ Asynchronous CBR mapping
03 ______ Bit synchronous CBR mapping
04 ______ ATM mapping
05 ______ GFP mapping
06 ______ Virtual concatenation signal
10 ______ Bit stream with octet timing mapping
11 ______ Bit stream without octet timing mapping
Payload type code points
Hex code Interpretation
20 _______ ODU multiplex structure
55 ______ Not available
66 ______ Not available
80 ______ Ciena’s OPVC mapping
81 - 8F __ Reserved codes for proprietary use
FD _____ NULL test signal mapping
FE ______ PRBS test signal mapping
FF ______ Not available
15
1
0
1
255
2
3
4
16
RES
RES
RES
PSI
JC
JC
JC
NJO PJO
17
JC [7,8] NJO PJO
00 Justification byte Data byte
01 Data byte Data byte
10 Not generated Not generated
11 Justification byte Justification byte
Optical Channel Payload Unit (OPU)
PT
Mapping &
Concatenation
specific
ODU3 OPU3
ODTUG3
ODTUG2
4X
4X
OTU3
OTU2f(11.270 Gbps)
OTU2e(11.049 Gbps)
ODU2f OPU2f
OPU2eODU2e
OTU2
OTU1
Ciena’s OTN Extensions
FE
OC-3/STM-1
ESCON
OC-12/STM-4
FC100
GbE
FC200
Any Rate
OTU1
1xOPTU1
Pointer Processing
Multiplexing
Aligning
Mapping
OPTUG1
OPVC1 GFP
GFP
GFP
GFP
GFP
GFP
OPVC1-7n
OTU2
OC-768/STM-256
3X 2G/4G FC
10G FC
10GbE (transparent)
OC-192/STM-64
10GbE
ODU2 OPU2
ODU1 OPU1
OC-48/STM-16
OTU3
2xOPTU1
4xOPTU1
6xOPTU1
7xOPTU1
12xOPTU1
XxOPTU1
OPVC1-2n
OPVC1-4n
OPVC1-6n
OPVC1-12n
OPVC1-Xn
OTN Multiplexing Structure
FA OH OTUk OH
OTUk FEC
(4 x 256 bytes)
Column
Column #
1 –––––––––––– 7 8 ––––––––––––14 15
1
2
3
4
Row
1
1
2 3
FAS MFAS
4 5 6 7 8 9 10 11 12 13
SM GCC0 RES
––––––––––––– 3824 3825 –––––––––––– 4080
SAPI
BIP-8TTI
DAPI
Operator
Specific
1
0
15
16
31
32
63
2 3
1 2 3 4 5 6 7 8
BEI/BIAE RES
BDI
IAE
FEC is used to increase system margin for a given Bit Error Rate (BER) and optical signal power. FEC detects and corrects errors providing an increase in
the signal-to-noise ratio, allowing longer spans.
ITU G.709 specifies a Reed-Solomon (RS) 255,239 code, also known as standard FEC. It provides 6 dB of coding gain. Each OTU row is separated into 16
subrows that are byte interleaved. Each sub row is 255 bytes. One FEC encoder/decoder is used to process each subrow. The first 239 bytes of the
subrow are used to calculate the parity which is placed in the last 16 bytes of the subrow. Ciena also uses an ITU G.975.1 Enhanced FEC (EFEC)
RS(1023,1007) interleaved with a Bose, Ray-Chaudhuri, Hocquenghem (BCH) 2047,1952 code. This code improves the coding gain to >8 dB while
maintaining the exact same data rate as the G.709 OTU.
The FEC enables the correction and
detection of errors in an optical link.
The Optical Channel (OCh) provides the end-to-end networking of individual optical channels for transparently conveying client information of varying
format. The OTU contains supervisory functions and conditions the signal for transport between 3R regeneration (re-timing, reshaping and regeneration)
points in the network. It contains the Frame Alignment Signal (FAS) and Multi-Frame Alignment Signal (MFAS) for each OTU.
The FAS is 6 bytes long containing the hex codes F6 F6 F6 28 28 28. The MFAS byte is a binary count from 0 to 255 incrementing once per frame.
When overhead signals span multiple frames, this byte is used to track and lock to a common frame.
The OTU also contains the overhead bytes for SM including the TTI, and the GCC.
Optical Channel (OCh)/Optical Transmission Unit (OTU)
Column #
RS 255,239 code
OTU OH and payload bytes FEC bytes
Sub-row#
Ciena enhances OTN capabilities with the OPVC. It provides transparent aggregation and sub-wavelength grooming via 155 Mb/s time slots that support
numerous low-speed TDM and data-based services maximizing network efficiency in the OTN layer.
OC-3/STM-1 1
ESCON 2
OC-12/STM-4 4
1 G FC - FC100 6
Gigabit Ethernet 7
2G FC-FC200 12
OC-48/STM-16 OTU1
Service # of Time Slots
GbE
ESCON
FC100
Gigabit Ethernet FC100
ESCON
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
1 1 1 1 1 1 1
Gigabit Ethernet FC100
STM-1/OC-3 OTU1 Frame
Header HeaderODU1 Frame
Mapped into ODU1 Frame
Client Signals
Client Port Interfaces
Unused
Unused
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
1 1 1 1 1 1 1
Time Slot Interchanger Function
1 2 3 4 5 6 7
1
1 2 3 4 5 6
Span 1
OTU1
Span 2
OTU1
STM-1.OC-3
ESCON
Gigabit Ethernet
STM-1/OC-3
FC100
Optical Channel Payload Virtual Container (OPVC)
Glossary
ATM Asychronous Transfer Mode
BDI Backward Defect Indication
BEI Backward Error Indication
BER Bit Error Rate
BIAE Backward Incoming Alignment Error
BIP8 Bit Interleaved Parity - level 8
CBR Constant Bit Rate
DAPI Destination Access Point Identifier
FA Frame Alignment
FC Fiber Channel
FE Fast Ethernet
FEC Forward Error Correction
GCC General Communications Channel
GFP Generic Framing Procedure
IAE Incoming Alignment Error
ITU International Telecommunications Union
JC Justification Control
MSTP Multiservice Transport Platform
NE Network Element
NJO Negative Justification Opportunity
OADM Optical Add Drop Multiplexer
OCC Optical Channel Carrier
OH Overhead
OLA Optical Line Amplifier
OOS OTM OH Signal
PJO Positive Justification Opportunity
PRBS Pseudo Random Bit Sequence
RES Reserved for future international standardization
SAPI Source Access Point Identifier
SM Section Monitoring
TDM Time Division Multiplexing
TTI Trail Trace Identifier
Ciena’s OTN-Enabled FlexSelect Architecture for End-to-End Networking
FlexSelect™
Architecture
Product Family
CoreDirector®
Multiservice Switch
CoreDirector®
CI
Multiservice Switch
CN 4200™
CN 4200™ RS
CN 4200™ MC
CoreSteam®
Agility
Optical Transport System
Research &
Education
OTU1/2
OTU1/2 OTU1/2/3
OTU1/2/3
OTU1/2
OTU1/2
OTU1/2
OTU2/3
Data
Center
Content
Provider
Wireless
Service
Aggregation
Broadband Access
Service Provider
DWDM
Metro
DWDM
Metro Core
Metro Core
Metro AccessFlexSelect Advanced Services Platform
FlexSelect Advanced Services Platform
FlexSelect Advanced
Services Platform
Ciena may from time to time make changes to the products or specifications contained herein without notice. ESCON is a registered trademark of International Business Machines, Inc. ©2007 Ciena Communications. All rights reserved.