The Optical Transport Network up to 100G

The Optical Transport Network (OTN) defined in ITU G.709 up to edition 4, 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. OTN Layers Optical Channel (OCh)/Optical Transmission Unit (OTU)
ODU The Optical Channel (OCh) provides the end-to-end networking of individual optical channels for transparently conveying client information of varying
OTN Advantages format. The OTU contains supervisory functions and conditions the signal for transport between 3R regeneration (re-timing, reshaping and regeneration)
Video OCh and OTU points in the network. It contains the Frame Alignment Signal (FAS) and Multi-Frame Alignment Signal (MFAS) for each OTU.
• Insulates the network against uncertain service mix by providing transparent native
OMS OMS 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 yo 255 incrementing once per frame.
transport of client signals encapsulating all client management information When overheard signals span multiple frames, this byte is used to track and lock to a common frame.
Ethernet
• Performs multiplexing for optimum capacity utilization thereby improving OTS OTS OTS OTS The OTU also contains the overhead bytes for SM including the TTI, and the GCC.

OTN network efficiency

Row
Column
1 78 14 15 3824 3825 4080

• Enables network scalability as well as support for dedicated Ethernet services 1 FA OH OTUk OH
OTUk FEC The FEC enables the correction and
ODUk Electrical ROADM OLA ROADM OLA ROADM Electrical 2
with service definitions for1GbE, 10GbE, 40GbE, and 100GbE, with higher rates Switch Switch 3 (4 x 256 bytes) detection of errors in an optical link.

beginning specification 4
Column #
SONET/SDH OTS monitors optical span connections between NEs Column #
1 2 3 4 5 6 7 8 9 10 11 12 13 14
• Provides multi-layer performance monitoring and enhances maintenance capability OMS monitors optical span connections between NEs with optical multiplex functions (OADMs) 1 FAS MFAS SM GCC0 OSMC RES 1 2 239 240 255
for signals transversing mult-operator networks OCh transports client signals between 3R regeneration points 1 1 17 3809 3825 4065
Client Ports OTU monitors electrical span connections between service switches

Sub-row #
1 2 3
2 2 18 3810 3826 4066
• Combined with Intelligent Control Plane, enables automated mesh connectivity ODU monitors end-to-end client paths for wavelength services TTI BIP-8

0 3 3 19 3811 3827 4067

and 50ms mesh restoration for a wide range of clients 15
SAPI
1 2 3 4 5 6 7 8
16 DAPI
BEI/BIAE RES

BDI
IAE
31
32 Operator
16 16 32 3824 3840 4080

Optical Transport Module (OTM) OTN Maintenance – Overhead Bytes 63

Specific OTU OH and payload bytes
RS 255,239 code
FEC bytes

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
The OTM is the information structure that is transported across the OTN node interface.
Column in the signal-to-noise ratio, allowing longer spans.
PSI
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 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
Digital 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
1 Frame Alignment MFAS SM GCC0 OSMC RES JC JC
PT subrow are used to calculate the parity which is placed in the last 16 bytes of the subrow. Equipment vendors typically also offer propriety enhanced
PM &
2 RES EXP TCM6 TCM5 TCM4 EXP JC JC
FEC options to improve the coding gain to >9 Db for a further increase in reach. The ability to turn off FEC is available in transport equipment that is
SONET/SDH, Ethernet, Client
TCM
Row 3 optimized for low-latency applications.

CSF
TCM1 TCM2 TCM1 PM EXP JC JC RES
IP/MPLS, etc... Note: G.709.2 will introduce OTU4-SC standardized enhanced FEC.
4 GCC1 GCC2 APS/PCC RES PSI NJO
OPU
For Client Service Mapping OH OCh Payload Unit (OPUk) Payload PM &
PM
Optical Channel (OCh)/Optical Transmission Unit (OTU)
TCM
Section, Path & Tandem Connection Monitor
For Switching ODU
OCh Data Unit (ODUk) Payload
1 2 3 4 5 6
DMp
7 8
1 2 3
OH
and Multiplexing TTI BIP-8 TCM6 TCM6 TCM6 TCM6 TCM6 TCM6 TCM6 TCM6 TCM6 TCM6 TCM6
OCh Transport Unit (OTUk) Payload TCMi PM & TCM5 TCM5 TCM5 TCM5 TCM5 TCM5 TCM5 TCM5 TCM5 TCM5 TCM5
TCM
0 TCM4 TCM4 TCM4 TCM4 TCM4 TCM4 TCM4 TCM4 TCM4 TCM4 TCM4 TCMi
For Transmission OTU
OH OCh Transport Unit (OTUk) Payload FEC ODUk 1 2 3 4 5 6 7 8 SAPI
TCM3 TCM3 TCM3 TCM3 TCM3 TCM3 TCM3 TCM3 TCM3 TCM3 TCM3 Overhead
DM1 DM2 DM3 DM4 DM5 DM6 (source) TCM2 TCM2 TCM2 TCM2 TCM2 TCM2 TCM2 TCM2 TCM2 TCM2 TCM2
15 SM BEI/BIAE BDI IAE RES TCM1 TCM1 TCM1 TCM1 TCM1 TCM1 TCM1 TCM1 TCM1 TCM1 TCM1
DMp-transmit DMp-receive 16

For Management Adaptation Near

End ODUk
OTN Far
End
DAPI
(destination)
TCMi BEI/BIAE BDI STAT

Analog DMp-receive DMp-transmit 31 PM BEI BDI STAT

Connection Monitoring End Point
32
Connection requires
coordination between Operator
OCh Optical Channel (OCh) the near- and far- end Specific
OH connection monitoring
ODUk Operator C Client
end point. 63 Operator A Signal
Operator B User
OCC OCC User
OH OH OCC OCC OCC Optical Carrier Channel (OCC) OCC Client

OTU Bit Rate Capacity

Signal

OTM OMS NNI CM NNI CM NNI CM

Overhead OH Optical Multiplex Section (OMS)
Signal OTU OTU Rate OPU Payload UNI CM
OTS Type (Gb/s) Rate (Gb/s) Client Signals
(OOS) QoS of Leased Connection is Monitored by User
OH Optical Transmission Section (OTS)
OTU1 2.6661 2.48832 STM-1/OC-3, STM-4/OC-12, STM-16/OC-48, Path CM
FC-100/200, 1GbE, CMGPON TCM provides nested performance monitoring for hierarchical operations and sectionalization.

OTU1e 11.049 10.3215 10GbE LAN (BMP w/o fixed stuff)

ITU-T OTN Hierarchy
OTU2 10.709 9.9953 STM-64/OC-192, FC-400/800, 10GbE WAN, OTN Benefit: maximize the efficiency of your network
10GbE LAN (GFP), IB SDR/DDR
STM-1/OC-3, STM-4/OC-12, Optimal network utilization with right-sizing of the
FC-100, 1GbE ODU0
2x
OTU2e 11.095 10.356 FC-1200, 10GbE LAN (BMP w/fixed stuff) New enhanced SLAs with sub-rated Ethernet
ODU1 bandwidth for all services carried over the network
STM-16/OC-48, FC-200 ODU1 OTU1 OTU3 43.018 40.150 STM-256/OC-768, 40GbE, IB QDR ODUflex containers can transport PLUS: Ethernet transport over any
a wide variety of multi-rate clients distance from metro to LH
16GFC, 32GFC, 40 x
FC-400, FC-800, Various, ODUflex 8x OTU4 111.80997 104.35597 100GbE Fiber Channel, OTN Switched 10GE, OTN Switched
ODUflex ODUflex
25GbE, 50GbE SDI Video, Transport Network 40GE,100GE Transport Network
ODU2 CPRI,
ODUflex OTU4
Ethernet
ODUflex OTU4
STM-64/OC-192, 10GbE ODU2 OTU2 InfiniBand
ODUflex
sub-rating
ODUflex

10GbE ODU1e OTU1e

OTN Applications Mobile
Backhaul
10 x • ODUflex containers map services, in 1.25G increments Flexibility to limit BW of each client to desired amount

Ciena may from time to time make changes to the products or specifications contained herein without notice. © 2022 Ciena Corporation. All rights reserved. 6.2022
Residential
FC-1200, 10GbE ODU2e OTU2e Services (such as FC400) more efficiently into OTN rather than with 1.25G/5G granularity
32 x
10 x Backhaul dedicating a full 2.5G (ODU1) or 10G (ODU2) per service.
• Subscriber purchases only the amount of BW needed
ODU3
3x • Asynchronous Mapping Procedure (AMP)
STM-256/OC-768, 40GbE ODU3 OTU3 • Providers can limit the BW entering their network per the SLA
Government,
• Bit-synchronous Mapping Procedure (BMP)
2x Research and
Ethernet/IP • Generic Framing Procedure (GFP)
Education
80 x Services • Generic Mapping Procedure (GMP)
Router
Interconnection Backhaul • Idle Mapping Procedure (IMP)
ODU4
100GbE ODU4 OTU4
Core OTN Mesh Further increase network bandwidth efficiencies with a right-sized ODUflex container
1GbE, 10GbE Retail
Metro Core OTN Mesh and Wholesale

Metro and Aggregation Ciena’s 6500 Family of Packet-Optical Platforms

OTN switching from the edge to the core scaling to 24Tb
Acronym guide Common OTN Control Plane
Fabric-based switching
Blade-based switching
6500 Family

OSMC OTN Synchronization Message Channel

6500-D2 6500-D4 6500-D7 6500-S8 6500-D14/S14 6500-S32 6500-T12 6500-T24