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OTN – Optical Transport Network

November 2016

José María Pindado BuendíaEngineering & Technology, EMEA

Copyright© ANRISTU2OTN- Optical Transport Network

OTN Background Architecture Overhead Structure OTN Functioning FEC Coding Gain

OTN – Bit Rates OTN - Mapping Recommended Test-Scenarios

OTN-Layer BER Error/Alarm Pass-through-Mode (OH-Overwrite)

FEC Client to Client (Based on RFC2544 / Y.1564)

Agenda


• OTN Background Architecture Overhead Structure Functioning FEC Coding Gain

OTN – Bit Rates OTN - Mapping

4 Copyright© ANRISTUOTN- Optical Transport Network

4

New Technologies: Network Changes BackBack

• Common Carrier Class Network– From Mobile to Core– From Copper to Fiber– From 2G to 4G

• Carrier Class Network changes– Removal of T1/E1 where possible– Core changes to ROADM, OTN, MPLS-TP– Migrate over time to remove SDH/SONET

T1/E1 TDM

(SDH/SONET)SDH/

SONET

T1/E1

RF 2G3G

LegacyBackhaul network

T1/E1

SDH /SONET /

ATM Core Network

3G4G

RRH

T1/E1

Central Office

T1/E1

RRH

RF Over Fiber

Base Station

Carrier Class Ethernet

over OTN

Ethernet

RRH

Business Connection

Next Gen Backhaul network

Node BROADM

Core Network

with MPLS-TP or PBB-

TE over OTN

Business Connection

InterfacesT1/E1 SDH/SONET Ethernet


Network-Segmentation

GE/10GbE

(RNC/BSC)

Core Router

GbE/10GbEFTTx, xDSL

Femtocell

OLT

ONU

Internet

ROADMROADM

OLT

EthernetSwitch TDM

Transport

10G OTN

40G / 100G

(BTS/NB)

RFOverGlass (Fiber)

Microcell/Picocell

(RRH)

CPRI

Mobile Fronthaul

Mobile Backhaul

Access

Core

Metro

8G/10G FC10GbE/40Gb

(Data Center)

SANBackBack


6

Challenges BackBack

(BTS/NB)

Mobile Backhaul

DS1/DS3, E1/E2/E3

GE

Micro wave

(RNC/BSC)

Core Router

Internet

RODAMRODAM

OLT

ONU

ONU

ONU

Mobile Network

Ethernet SwitchTDM Transponder

PON

TDM

RFOverGrass Fibre

SDH/SONET

10G OTN

40G / 100G

Microcell

Microcell/Picocell

Microcell/Picocell

Microcell

(RRH)

Several network technologies are mixed, like PDH, SDH, Ethernet…⇒ Solution of complex maintenance

and operation management

(1) Grow traffic⇒ Expand traffic capacity⇒ Improve traffic efficiency

(2) High quality network for added value service like VoLTE, SLA…

Reduce CAPEX / OPEX by migration from Legacy to Ethernet

・TDM (E1/T1) ⇒ GbE/10GbE・Synchronize Ethernet networks

Traffic growing continuously⇒ Focus to expand traffic capacity

The latest high speed network・ 100G Ethernet / 100G OTN・ 400G or more (2017~)

(1) The latest high speed network (100GEthernet / 100G OTN)

(2) Improve traffic efficiency by ODU-XcPriority management and traffic engineering network


7

OTN was designed at first for Submarine networks Quickly moved all the way to the Core Metro Access

Operators able to implement better services, control & management Control customer traffic from the access point & across the network (single system single

management) Greater insight to faults, quick repair & reduces maintenance issues Single management of all technologies Legacy and Replacement Contribution to reduce the power budget of each network line and Tx/Rx port

OTN -Background BackBack


OTN - Background

ITU-T (G. 709) defines Optical Transport Network (OTN) as a group of Optical Network Elements (ONE), connected with an optical fiber to transport, multiplexing, switching, managing, monitor /control to provide optical channels with user/client data.Typical signals, transported via OTN:

SONET/SDHEthernetFibre Channel (CPRI)

Key functions of OTN:Mapping / Demapping of non-OTN signals Multiplexing and Demultiplexing of OTN signals (OPU and

ODU’s) Forward Error Correction

8

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Chronological development SDH

Good fault management, performance monitoring and protection mechanism Not suited for packet based traffic Provides a deterministic and connection-oriented network

These are the Key Points for a Telecom Network

Ethernet/IP– Efficient and with low costs in comparison to SDH– Provides a non-deterministic and connectionless network in order to achieve

minimum overhead/management – No fault management, performance monitoring or protection mechanism

9

OTN - Background BackBack


Architecture

12

OTS Area between EDFA´s and optical elementOMS Area between two optical elementsOch Area between two digital elementsOTU Area between two digital elementsODU/OPU Area between edge to edge elements

Overhead per Layer enables further Management (Fault location etc.)BEI of ODU Layer; indicates BIP-8 of a single connection (client) BDI of OTU Layer; more critical

BDI (Backward Defect Indication)BEI (Backward Error Detection)BIP-8 (Bit Interleaved Parity-8)

Digital Domain

Optical Amp Optical ADMDigital ADM

Optical ADMDigital ADM Operator or

Customer

OTS OTS

OMS

OCh (Channel)

OTU (Section)

ODU (Path)

OPU (Payload)

Operator or Customer

Optical Domain

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Mechanism- Signal Interaction

13

Key for all What is the cause of an Error/Alarm What happens, if an

Error/Alarm occurs E.g..: if LOF is de-

tected, a BDI must be returned by network-element

If the cause of a BDI is known, the problem can quickly be solved

If the level of an Error/Alarm is known, the nature and scale of the problem can be evaluated more easily Total Network or

On Client side only

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Overhead Structure

OPU Overhead

OTU Overhead section

Frame Alignment Signal SM

OPU PayloadRES PM &

TCMTCM ACT TCM6 TCM5 TCM4 FTFL

TCM3 TCM2 TCM1 PM EXP

GCC1 GCC2 APS/PCC RES

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 …………………….….. 3824

1

2

3

4

OTU FEC

3825 ……………………. 4080

Column No#

Row

No#

MFAS GCC0 RES

ODU Overhead section

PSI NJO

RES JC

RES JC

RES JC

PJO

OTN OH similar to SDH •FAS and OTU similar RSOH•ODU similar MSOH•OPU similar Ho POH•OPU Payload similar to C-4 Payload

OTN is based on a fixed Frame size and consists of three areas: Overhead sectionPayload sectionFEC (Forward Error Correction) section

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OTUk Overhead

Frame Alignment SignalFAS (Frame Alignment Signal)MFAS (Multi Frame Alignment Signal)

SM (Section Monitoring)TTI (Trail Trace Identifier) SAPI (Source Access Point Identifier)DAPI (Destination Access Point Identifier),BIP-8 (Bit Interleaved Parity-8),BEI/BIAE (Backward Error Indication and Backward Incoming Alignment Error), BDI (Backward Defect Indication),IAE (Incoming Alignment Error),

GCC (General Communication Channel),

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OPU Overhead

OTU Overhead Section


OPU PayloadRES PM &




1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 ………………… 3824

1

2

3

4

OTU FEC

3825 ………………. 4080

Column Nr.#

Row

Nr.#

MFAS GCC0 RES

ODU Overhead Section

PSI

SM Section

TTI BIP-8

SAPI

DAPI

Operator Specific

BEI/BIAE BDI

IAE RES

1 2 3 4 5 6 7 8

1 2 3

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ODUk Overhead

• PM (Path Monitoring),– TTI (Trail Trace Identifier),– BIP-8 (Bit Interleaved Parity-8),– BDI (Backward Defect Indication),– BEI (Backward Error indication),– STAT (STATus bits),– DMp (path Delay Measurement),

• TCM ACT (Activation/Deactivation),• TCM (Tandem Connection Monitoring),

– TTI (Trail Trace Identifier),– BIP-8 (Bit Interleaved Parity-8),– BDI (Backward Defect Indication),– BEI/BIAE (Backward Error Indication and backward Incoming Alignment Error),– STAT (STATus bits),– DMti (Delay Measurement TCMi i=1 to 6)

• FTFL (Fault Type and Fault Location),• EXP (Experimental Overhead),• GCC1 and GCC2 (General Communication Channels 1/2),• APS/PCC (Automatic Protection Switching and Protection Communication Channel).

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OPU Overhead



OPU PayloadRES PM &




1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 ………………... 3824

1

2

3

4

OTU FEC

3825 ………………. 4080

Column Nr. #

Row

Nr.

#

MFAS GCC0 RES


PSI

TCMi Section

PM & TCM

TTIi BIP-8i

SAPI

DAPI

Operator Specific

BEIi/BIAEi BD

Ii

STATi

1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

1 2 3

DM

t1

DM

t2

DM

t3

DM

t4

DM

t5

DM

t6

PM Section

TTI BIP-8

SAPI

DAPI

Operator Specific

BEI BD

I

STAT

PM & TCM

DM

p

1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

1 2 3

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OTN Functioning….

17

OTU section has three areas FAS (Frame Alignment) and MFAS (Multi Frame Alignment)

Shows the start of the frame and MFAS Section Monitoring

Includes details for each section (between any two Switches) Source- and destination address Parity check Backward Error Indication

GCC0/1/2 (General Communication Channel) ODU section

Includes details of the total path (often assignable to clients) Source- and destination address Parity check Backward Error indication Delay measurement FTFL (Fault Type and Fault Location), to indicate fault-status und -location APS/PCC (Auto Protection Switching / Protection Communication Channel), Data

may pass a different part of the network TCM (Tandem Connection Monitoring) Section, enables the monitoring of individual

sections (various carrier) of an end to end network

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OPU Overhead



OPU PayloadRES PM &




1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 …………….….. 3824

1

2

3

4

OTU FEC

3825 ………………. 4080

Column No#

Row

No#

MFAS GCC0 RES


PSI NJO

RES JC

RES JC

RES JC

PJO

OPU Overhead

Controls various Client Signal Mappings into the PayloadAMP (Asynchronous Mapping Process)BMP (Bit synchronous Mapping Process)GMP (Generic Mapping Procedure)

Based on PT (Payload Type) Overhead bits willbe adapted

PSI (Payload Structure Identifier)PT (Payload Type)CSF (Client Signal Fail)

JC (Justification Control)NJO (Negative Justification Opportunity)PJO (Positive Justification Opportunity)

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PSI & JC Section

…

…

PT

RES

Reserved JC

1 2 3 4 5 6 7 8

1

1

2

255

CSF

1 2 4

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OPU Overhead



OPU PayloadRES PM &




1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 …………….….. 3824

1

2

3

4

OTU FEC

3825 ………………. 4080

Column No#

Row

No#

MFAS GCC0 RES


PSI NJO

RES JC

RES JC

RES JC

PJO

FEC

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FEC Parity check-Bytes are calculated over the Information-Bytes 1 to 239 of each Sub-Row and inserted in the Bytes 240 to 255 of the same Sub-Row. In total there are 16 Sub-Rows.

The theoretical efficiency of the errorCorrection are calculated based on occurrence of randomized errors.

20 Copyright© ANRISTUOTN- Optical Transport Network Technology Overview

20

OPU section consists of two areasOverhead

Includes Payload Structure Identifier (PSI) and Payload Type (PT), the Overhead in connection with Concatenation and Overhead (e.g. Justification Control und Opportunity Bits) for mapping of client data into OPUk Payload

Payload Container to carry the client data

FEC Improves the erroneous behaviour and for longer

optical transmission path (use of Reed Solomon Codes; RS(255,239)) Bitrate expansion due to FEC-Algorithm by 7% Improves the SNR by up to 6,2 dBCorrection of up to 8 symbol error

….OTN Functioning BackBack


OTN Bit Rates - OTU OTU is a physical interface in an OTN Network.

ITU-T Recommendation G.709 Optical Transport Network (OTN) line rates:

OTU: Optical channel Transport Unit

OTN TypeFEC Multiplier

Multi-plier

Payload-rate

OTU Rate Gbit/s Ideal Payload

OTU1 255 238 2.488 320 2.666 057 STM-16/OC-48, 1GFC/2GFCOTU1e 255 238 10.312 500 11.049 107 10GigE LANOTU1f 255 238 10.518 750 11.270 089 10GFCOTU2 255 237 9.953 280 10.709 225 STM-64/OC-192, 4GFC/8GFCOTU2e 255 237 10.312 500 11.095 728 10GigE (LAN)OTU2f 255 237 10.518 750 11.317 642 10GFCOTU3 255 236 39.813 120 43.018 414 40GigE, STM-256/OC-768OTU3e1 255 236 4 10.312 500 44.570 975 4xODU2eOTU3e2 243 217 16 2.488 320 44.583 356 4xODU2eOTU4 255 227 99.532 800 111.809 974 100GigE

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1

2

3

4

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OTN 10 Gb/s Mappings

2

1

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OTN 40Gb/s Mappings

3

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OTN 100Gb/s Mappings

4

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Recommended Test-Scenarios OTN-Layer BER Error/Alarm Pass-through-Mode (OH-Overwrite) FEC Analog-Method Digital-Method

Client to Client (Based on RFC2544/Y.1564)

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OTN-Layer BER Error/Alarm Pass-Through-Mode

ODU-Multiplexing FEC Analog-Method Digital-Method


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OTN Network Partition

RFC2544/Y.1564 TestOTN-Layer Test BER Error/Alarm FEC

OTN-Layer Test BER Error/Alarm FEC

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Error/Alarm Status-check Monitoring of SM/PM

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Investigation on various mappings in order to view the results based on Client-level

E.g. BER at 1GbE

BER-Analysis BackBack


OTN-Frequency-Offset BackBack


OH-Header Manipulation BackBack


OTN-Error/Alarm-Injection BackBack


Pass-Through-Mode; OH transparent/overwrite

MEME

Bidirectional monitoringEvaluate if Network-Element shows the correct response

to Error situation. (OTU-AIS; SM-BDI )

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ODU MultiplexingSimulation of various Client-Signals (Eth., CPRI etc.)

ThroughputBER

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ODU-Multiplexing FEC-Test Analog-Method Digital-Method


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Analog MethodRandom Error generation by varying the SNR using an optical attenuator. Input Error Ratio is determined with FEC disabled With FEC enabled the Error-Correction-Efficiency can be

obtained

FECEncoder

ME

Optical Attenuator

Optical Attenuator

FECDecoder

ME

DUT

FEC Efficiency

FEC Error Addtition=Off

1.FEC=Off2.FEC=On

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Digital Method

FECDecoder

DUTFECEncoder

MERandom Error Addition = On

ME

FEC=OnFEC=On

Random Error injection based on Poisson-Distribution in accordance with ITU-T O.182

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Digital MethodReproducible and accurate FEC-Error-Correction -Test: Error generation based on Poisson-Distribution in accordance with ITU-T O.182

FEC Efficieny

Poor characteristic of Poisson-Distribution Good characteristic of Poisson-Distribution

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Digital MethodReproducible and accurate FEC-Error-Correction -Test: Error generation based on Poisson-Distribution in accordance with ITU-T O.182

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ODU-Multiplexing FEC-Test Analog-Method Digital-Method


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RFC2544 / Y.1564; Client to Client / Embedded

RFC2544/Y.1564 Test

RFC2544 / Y.1564 Test EmbeddedRFC2544 / Y.1564 Test Embedded

RFC2544 / Y.1564 Test End to EndRFC2544 / Y.1564 Test End to End

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What does RFC2544 mean?

The RFC2544 defines Test-Scenarios to benchmark and characterize the performance of Network-Equipment. Throughput; Latency ; Frame Loss Rate ; Back to Back Frames

(Burstability / Fragmentation-Defragmentation) The Tests should be performed at a number of frame sizes – at

least five frame sizes should be tested for each test condition. Frame sizes: 64, 128, 256, 512, 1024, 1280, 1518

Furthermore the format for reporting the results is described.

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Test-Setup

TesterTester

1.

Tester TX (RX)Tester TX (RX) Tester RX (TX)Tester RX (TX)

2.

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TesterTester

DUT 1(e.g. 1GbE)

DUT 1(e.g. 1GbE)

DUT 2(e.g. 1GbE)

DUT 2(e.g. 1GbE)WAN

3.


ITU-T Y.1564 Service Activation Test ITU-T Y.1564 completes the testing in two phases

Service Configuration TestConfirm each individual service is configured correctly checking, CIR (Committed Information Rate), EIR (Excess Information Rate), FTD (Frame Transfer Delay), FDV (Frame Delay Variation), FLR (Frame Loss Ratio), CBS (Committed Burst Size), EBS (Excess Burst Size).

Service Performance TestTransmits one or many Service Configuration Tests simultaneously at the CIR confirming all traffic is able to traverse the network under the full service load over time.

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Comparison of Y.1564 and RFC2544

RFC 2544; common Defined for benchmarking Network-Equipment Only run a test at a time (no simultaneous

verification)

ITU-T Y.1564 RFC 2544Designed for Service activation Devices performanceConcurrent services Multiple services simultaneously One service at a timeSimulates A realistic network One service in a networkTesting time Short due to simultaneous test /

serviceLong due to serial nature of test

Test result Directly related to SLA requirements Link performance limit

Test-Methodology

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One doesn’t replace the other they are designed for different tasks

Y.1564 RFC 2544 Comment

Designed for Element testing.

No Yes When testing a single component you should stress it and multiple frame sizes sequentially.

Designed for Network testing.

Yes No When testing a network you should stress by generating multiple streams at the same time.

Fast testing time. Yes No The testing time can be almost the same depending on the settings but if the full RFC is completed it is very long. Y.1564 can take longer but allows the user to select shorter measurement times if they wish.

Settings work with SLA’s.

Yes No Y.1564 settings can be configured based on customers SLA agreements.

Works on a loaded network.

Yes No Both are able to work on active networks but RFC 2544 is designed to find the network limit while Y.1564 is designed to find the circuit limit. Incorrectly configured either will bring affect customer traffic.

Comparison of Y.1564 and RFC2544 BackBack

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