Backward Direction Forward Direction

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. 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 Cienas 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

OTN Networks
The OTU also contains the overhead bytes for SM including the TTI, and the GCC.
Column 1 7 8 14 15 3824 3825 4080 Row

Optical Channel Data Unit (ODU)

COLUMN# 1 2 1 3 3 4
ROW#

2 RES TCM3 GCC1

4
TCM ACT

GCC2 0 1 9 10

6 7 TCM6 TCM2 APS/PCC

9 10 TCM5 TCM1

11

12 13 TCM4

PM RES

14 FTFL EXP

The ODU allows the user to support Path Monitoring (PM), Tandem Connection Monitoring (TCM) and Automatic Protection Switching (APS).
TCMi/PM 1 TTIi 2 BIP-8i 3

TCM enables signal management across multiple networks. 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 PM enables the monitoring of particular sections within the network and fault location.

Optical Channel (OCh)/Optical Transmission Unit (OTU)

FAULT INDICATION FIELD

OPERATOR IDENTIFIER FIELD

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.

OPERATOR SPECIFIC FIELD

FAULT INDICATION FIELD

OPERATOR IDENTIFIER FIELD

127 128 129 137 138

Fault Type and Fault Location channel (FTFL) A 256 byte multi-frame signal providing fault status information regarding type and location of the fault. Fault indication codes
API
Fault indication code Definition

0 1 15 16 31 32 63

0x00 SAPI 0x00 DAPI Operator Specific

1 1

2 3 4 5 6 7 8 BEIi/BIAEi BDIi STATi 2 BEI 3 4 5 6 7 8 BDI STAT

TCM PM

0000 0000 0000 0001 0000 0010

0000 0011 . . . 1111 1111

No fault Signal fail Signal degrade Reserved for future international standardization

OPERATOR SPECIFIC FIELD

255

Optical Transport Module (OTM)

The OTM is the information structure that is transported across the OTN node interface

1 2 3 4
1 1

FA OH

OTUk OH

OTUk FEC (4 x 256 bytes)

Column #

The FEC enables the correction and detection of errors in an optical link.

Operator Identifier Field Structure G/PCC Geographic/Political country code

129 130 131 1 2 3 Country code G/PCC G/PCC G/PCC G/PCC G/PCC 132 4 ICC ICC ICC ICC ICC ICC NULL 133 134 135 136 5 6 7 8 National segment code Null Padding Null Padding Null Padding Null Padding
Null Padding

Access Point Identifier (API) structure CC Country Code ICC ITU Carrier Code IS International Segment NS National Segment UAPC Unique Access Point Code
NS Character #

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

137 9

OTUk TCMi & PM BEI/BIAE bits 1234 08 915 11 (N/A for PM)

Interpretation

IS Character #

3 FAS

7 MFAS

9 SM

10

11

12

13 RES

Column #

GCC0

BIP error No BIP error BIAE, no BIP error

Sub-row #

Optical Transmission Section (OTS) Optical Multiplex Section (OMS)

OCC OCC OCC OCC

OTS OH OMS OH O C C o OCh OH O C C o

1 TTI

2 BIP-8

G/PCC

2 3 4 5 6 7 CC ICC ICC CC CC ICC CC ICC CC ICC CC ICC

9 10 11 12 13 14 15 UAPC UAPC UAPC UAPC UAPC UAPC

BEI/BIAE

BDI IAE

OOS
O C C o

0 15 16 31 32

SAPI DAPI Operator Specific

1 2 3 4 5 6 7 8 RES

Optical Channel Payload Unit (OPU)

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

63

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.
15 1 2 3 4 RES RES RES PSI 16 JC JC JC NJO PJO 17

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.

Payload type code points

Hex code 01 ______ 02 ______ 03 ______ 04 ______ 05 ______ 06 ______ 10 ______ 11 ______

OCh
OTU OH ODU OH OPU OH

OTU Payload ODU Payload OPU Payload

OPVC Payload (Ciena)
Low-speed SONET/SDH, GFP, Ethernet FC100/200, ESCON, Video, Other

FEC

Interpretation Experimental mapping Asynchronous CBR mapping Bit synchronous CBR mapping ATM mapping GFP mapping Virtual concatenation signal Bit stream with octet timing mapping Bit stream without octet timing mapping

Payload type code points

Hex code Interpretation 20 _______ ODU multiplex structure 55 ______ Not available 66 ______ Not available 80 ______ Cienas OPVC mapping 81 - 8F __ Reserved codes for proprietary use FD _____ NULL test signal mapping FE ______ PRBS test signal mapping FF ______ Not available

OTU Bit Rate Capacity

Container Type OTU1
Channelized*

JC, NJO and PJO generation by asynchronous mapping process

0 1 255

PT Mapping & Concatenation specific

JC [7,8] 00 01 10 11

NJO Justification byte Data byte Not generated Justification byte

PJO Data byte Data byte Not generated Justification byte

Line Rate (Gbps) 2.6661 2.6661 10.709 11.049 11.270 43.018

Payload Rate (Gbps) N x 0.15552 2.48832 9.9953 10.3125 10.51875 40.151

Frame Period (s) 3134.2* 48.971 12.191 11.816 11.585 3.035

Client Signal
OC-3/STM-1, ESCON, FC100/200, 10/100/1000 Base-T, GbE

ITU G.709 OTN Standard Bit Rates

OTU1

OC-48/STM-16
OC-192/STM-64,10GbE WAN, 10GbE LAN PHY (MAC Frames)

OPVC OH

Optical Channel Payload Virtual Container (OPVC)

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.
STM-1.OC-3

Client

OTU2 OTU2e

10GbE (Transparent) 10G FC (Transparent) OC-768/STM-256

Gigabit Ethernet
ESCON

FC100

SONET/SDH, ATM, Ethernet, Other

OTU2f OTU3

OTN Extensions

Service OC-3/STM-1 ESCON OC-12/STM-4 1 G FC - FC100 Gigabit Ethernet 2G FC-FC200 OC-48/STM-16

# of Time Slots 1 2 4 6 7 12 OTU1

U1 OT

1 1 1 11 1 1 1 2 3 45 6 7 8 9 0 1 2 3 4 5 6
OTU1

ESCON
Span
2

Unused
GbE ESCON

OTN Layers
ODU and OPVC OCh and OTU OMS
OTS OTS OTS

*OPVC payload container. OPVCs can be concatenated in 155.52 Mb/s containers.

n Spa

Glossary
ATM Asychronous Transfer Mode Backward Defect Indication Backward Error Indication Bit Error Rate Backward Incoming Alignment Error Bit Interleaved Parity - level 8 Constant Bit Rate Destination Access Point Identifier Frame Alignment Fiber Channel Fast Ethernet FEC GCC GFP IAE ITU JC MSTP NE NJO OCC Forward Error Correction General Communications Channel Generic Framing Procedure Incoming Alignment Error International Telecommunications Union Justification Control Multiservice Transport Platform Network Element Negative Justification Opportunity Optical Channel Carrier OH OLA OOS PJO PRBS RES SAPI SM TDM TTI Overhead Optical Line Amplifier OTM OH Signal Positive Justification Opportunity Pseudo Random Bit Sequence Reserved for future international standardization Source Access Point Identifier Section Monitoring Time Division Multiplexing Trail Trace Identifier

Time Slot Interchanger Function Client Signals Gigabit Ethernet 1 2 3 45 6 7 Gigabit Ethernet FC100 Header ODU1 Frame OTU1 Frame

FC100

OMS
OTS

BDI BEI BER BIAE BIP8 CBR

STM-1/OC-3

1 1 1 11 1 1 1 2 3 45 6 7 89 0 1 2 3 4 5 6 STM-1/OC-3 Unused

Header

MSTP OADM

OLA

OADM

OLA

OADM MSTP

DAPI FA FC FE

FC100

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 Optical Add Drop Multiplexer

1 2 3 45 6 Client Port Interfaces

Mapped into ODU1 Frame

Cienas OTN-Enabled FlexSelect Architecture for End-to-End Networking

FlexSelect Architecture Product Family
CoreSteam Agility
Optical Transport System

OTN Multiplexing Structure

OTU3 OTU3 ODU3 OPU3 ODTUG3
(11.270 Gbps)

Research & Education

Content Provider

OC-768/STM-256

Broadband Access Service Provider

OTU2f

ODU2f ODU2e

OPU2f OPU2e

10G FC 3X 2G/4G FC

OTU2e (11.049 Gbps)

10GbE (transparent) OTU2 4X

Data Center
OTU1/2

OTU1/2

OTU1/2

OTU2

ODU2

OPU2 ODTUG2 4X

OC-192/STM-64 10GbE

CoreDirector
Multiservice Switch

OTU1/2/3

OTU2/3

OTU1/2

OTU1

ODU1

OPU1 1xOPTU1 OPVC1 GFP

OC-48/STM-16 FE OC-3/STM-1

DWDM Metro

Core

CoreDirector CI
Multiservice Switch

DWDM Metro
OTU1/2/3

OTU1/2

Pointer Processing Multiplexing Aligning Mapping Cienas OTN Extensions OPTUG1

2xOPTU1 4xOPTU1 6xOPTU1 7xOPTU1 12xOPTU1 XxOPTU1

OPVC1-2n OPVC1-4n OPVC1-6n OPVC1-7n OPVC1-12n OPVC1-Xn

GFP

ESCON OC-12/STM-4

GFP GFP GFP GFP

FC100 GbE FC200 Any Rate OTU1

CN 4200 RS
FlexSelect Advanced Services Platform

Metro Core

CN 4200
FlexSelect Advanced Services Platform

Wireless Service Aggregation

CN 4200 MC
FlexSelect Advanced Services Platform

Metro Access

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.