OTN Class

Centre de Comunicacions Avanades de Banda Ampla (CCABA)

Optical NetworksOptical Transport Networks (G.872, G 709) (G.872 (G 872, G.709)

Optical Internet

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ContentsIntroduction: Optical Networks Evolution 2. Optical Networks research activities at UPC 2 3. Optical Network Enabling technologies 4. Traffic Engineering Basics 5. ASON/GMPLS networks 6. G.709/OTN 7. Resiliency in Optical Networks y p 8. Resilient Packet Rings (RPR) 9. Metropolitan/Access Optical Networks 10. Packet Oriented Optical Networks1.10/12/2008

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ContentsIntroductionh h

Current architecture: SDH/WDM WDM technology

Transport networks evolution Optical Transport Networks architecture (G.872)h

Layers: OCh, OMS, OTS Och sub-layers (OPU ODU, OTU) (OPU, ODU Frame format Forwarding Error Correction (FEC) Implementation and advantatges

OTN Interfaces (G.709)h h h

Conclusions3 10/12/2008

Optical Internet

Transport networksCurrent transport networks architecture: SDH/WDMADM ADM DXC ADM

ADM

SONET/SDH Ring

SONET/SDH Ring

DXC ATM ADM IPRouter VCs ADM

ADM /PoE

SONET/SDH Ring

ADM OC12 OC3 OC48

ATM switch OC3 SDH ADM

IP ADM4 10/12/2008

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Point-to-Point DWDM

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Introduction to WDM technology (I) (I)Optical bandwidth utilizationWDM: Multiplexing different wavelenghts over the same optical fiber

OTDM: Temporal multiplexing of different traffic flows over the same optical carrier p

OCDM: The information signal is multiplied by an optical code5 10/12/2008

Optical Internet

Introduction to WDM technology (II)WDM technology allows to take benefit from:Bandwidht provided by optical fibers Optical amplifiers technology

Canal 1 Canal 2

Mux / Dmux x

Mux / Dmux x

1 2 3 4 N N+1

1 2 3 4

Canal 1 Canal 2

Fibra ptica

Canal N

N N+1 Canal N

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Introduction to WDM technology (III)WDM technologyGrid (ITU T) G.694.1 (ITU-T) G 694 1 C band N = 40 channels START= 1569.59 nm END = 1530.33 nm f=100 GHz; =0.804 nm8 6 4 2 950 1100 1250 1400 1550 1700

[dB/Km] [dB/K ]

70

120

Grid (ITU-T) G.694.2 0 N = 16 (18) channels (G.652.C, 800 G.652.D) START = 1310 nm END = 1550 nm f=2500 GHz; =20 nm

[nm]

012

N

Optical amplifiersh7 10/12/2008

C band (1530-1565 nm) and L band(1570-1610 nm)Optical Internet

CWDM vs. DWDMOptical transceivers:DWDM (it requires control of temperature) higher cost CWDM (it does not require control of temperature) lower cost

Channel spacing: DWDM: 200 GHz, 100 GHz, 50 GHz, 25 GHz CWDM: 20 nm DWDM capacity>> CWDM capacity Applications:CWDM: Metropolitan networks DWDM: Backbone networks8 10/12/2008

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Current architecture: drawbacksWDM allows to increase the transport capacity but the switching functionalities is at electrical domain Switching matrix: STM-1/STM-4/STM-16Transmitters

1 2 3WDM Mux

Optical Fiber

Receivers

R RWDM DeMux

A

O-ESTM-16

E-OADM ADM

A

STM-1

Amp

Amp 40 - 120 km

RSTM-16

DXCADM ADM

NODE DXC

N = 50 or 100 GHz

Up to 10,000 km

R

A

O-E

E-O

A

Scalability issues ant very high bit rates (40Gbit/s and beyond)Solution: Switching of optical signals9 10/12/2008

Optical Internet

Evolution of transport networksRemoving SONET/SDH layer and providing optical layer with the removed SONET/SDH functions:h

Protection, Restoration, Monitoring, etc.

Replace SONET/SDH nodes with optical nodes in which the switching is done transparently at the optical level:h

h

OXC: Optical Cross-Connect, with capacity of routing optical wavelengths between several nodes OADM: Optical OADM O i l Add D Drop M l i l Multiplexer, with capacity of adding and ih i f ddi d dropping optical wavelength from the DWDM multiplex

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Optical TransportOptical Internet (OTN) Networks

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Optical Transport Networks (OTN) (OTN)OTN instead of SONET/SDHh h h

A further step towards network convergence Migration towards a network i f Mi i d k infrastructure IP/E h IP/Ethernet over WDM OTN is the option chosen by Network Operators as the technology for the transport of data Transparent transport of client signals Scalability FEC Reduction of 3R regeneration(Re-amplifiyin, Re-timing, Re-shaping) It requires new hardware and management sytem

Advantages:h h h

Drawbacks:h

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Optical Internet

Optical Transport Networks (OTN)Most of OTN concept derived from SDH (layers model, management functions, supervision, etc.) New functionalities have been added: h End-to-end optical channel management h Introduction of FEC to allows longer optical pathsTx1

domain of transparency1

Rx

OADM

OADM

N

DEMUX

2

2

MUX

a

d

a

d

N

Tx12 10/12/2008

Rx

Tx

Rx

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Standard: processOTN standardized by ITU-Th Basic

definition of the OTN architecture

G.872 (1999-11/2001) Layers model: OCh, OMS i OTS h Interfaces

definition

G.709/Y.1331 G 709/Y 1331 (03/2003) Sub-layers model: OPU, ODU i OTU OTU frame format FEC

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Optical Transport Networks (OTN)1ITU-T G.872 is the standard to transport wavelenghts in DWDM trasnparent networks ph

Also known as OTH (Optical Transport Hierarchy) Inter-domini (IrDI) Intra-domini (IaDI)

2 interfaces defined:h h

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Optical Internet ITU-T G.872, Architecture for Optical Transport Network, 11/2001

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Optical Transport Networks (OTN)G.872 consists of three sub-layers which provide OAM functionalitiesh h h

Optical Channel (OCh): funcionalities to manage optical channels which transport different client signals Optical Multiplex Section (OMS): funcionalities to manage multiplexed optical signals Optical Transmission Section (OTS): funcionalities to manage the transmission of optical signal over fibres (G.652, G.653, G.655).STM-N STM N OMSn OTSn OTSn OTSn3R

DXC3RCliente: IP, ATM, SDH15 10/12/2008

OCh OMSn OTSn OADM OXCOptical Internet

OMSn OTSn OTSn R LT3R STM-N Cliente: IP, ATM, SDH

LT

R

R

DXC

Optical Transport Networks (OTN)OTN connection example

Electronic layersTx Rx

OCh OMS OTS Physical media

DXC16 10/12/2008

Electronic switch

OXCOptical Internet

Mux

Optical switch

Demux

EDFA

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Optical Transport Networks (OTN)OTN connection example: Och layer

Electronic layersTx

OCh trailRx


DXC17 10/12/2008

Electronic switch

OXCOptical Internet

Mux

Optical switch

Demux

EDFA

OTN sub-layers: Optical Multiplex subSection (OMS)This layer allows functionalities of management of multiplexed optical signals (Optical Section) The functionalities of this sub-layer include:h Supervision

functions at optical section level for OMS

management OMS Protection (survivability)

Equipments involved: sub-systems for mux/demux

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OTN sub-layers: Optical Multiplex subSection (OMS)Basic functions (OMS trail terminations)h

To test the quality of the transmission Detecting errors in the transmission

h

Monitoring of the wavelengths to detect variations with respect to the nominal value (wavelength drift)

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Optical Internet

Optical Transport Networks (OTN)OTN connection example: OMS layer

Electronic layersTx

OCh trailRx OMS trail OMS trail OMS trail


DXC20 10/12/2008

Electronic switch

OXCOptical Internet

Mux

Optical switch

Demux

EDFA

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OTN sub-capes: Optical Transport subSection (OTS)This sub-layer provide functionalities for the transmission of optical signals in optical fibers (G.652, G.653 and G.655) Among others:h h

Functions of supervision of the OTS management operations at OTS layer. To test the quality of the transmission Monitoring of the optical power for the WDM channels

section

to

allow

Equipments involved: EDFA amplifiers

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Optical Internet

Optical Transport Networks (OTN)OTN connection example: OTS layer

Electronic layersTx

OCh trailRx OMS trail OMS trail OMS trail


OTS trails

OTS trail

OTS trails

DXC22 10/12/2008

Electronic switch

OXC

Mux

Optical switch

Demux

EDFA

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Optical Transport Networks (OTN)An OTN is composed by optical nodes (OADMs, OXCs) connected through optical fiber linksOADM OXC OADM

OADM

Optical Ring (Uni or Bi)

Optical Ring

OXC ATM OADM

OADM

OADM

Optical Ring

OADM

IP ADM23 10/12/2008

Optical Internet

Optical Transport Networks (OTN): G.872 and G.709Layersh

Optical Channel (OCh):Optical channel Transport Unit (OTU) Optical channel Data Unit (ODU) Optical channel Payload Unit (OPU)

h h

Optical Multiplex Section (OMS) Optical Transport Section (OTS)Optical Channel - Payload Unit (OPUk)

IP

ATM

Ethernet

STM-N

Optical Channel - Data Unit (ODUk)

Optical Channel (OCh)

Optical Channel - Transport Unit (OTUk)

Optical Multiplex Section (OMSn)

Optical Transmission Section (OTSn)24 10/12/2008

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Optical Transport Networks (OTN): G.7092Functions of OPU sub-layerh

Adapt the client signals End-to-end connection supervision Tandem Connection management Monitoring of the signals bewteen regeneration points FEC processing

Functions of ODU sub-layerh h

Functions of OTU sub-layerh h

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Optical Internet ITU-T G.709, Interfaces for the Optical Transport Network (OTN), 03/2003

Optical Transport Networks (OTN): G.709Signal clients mapping3

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R.Gendron, The G.709 Optical Transport Network, An overview, Appl. Note 153

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Optical Transport Networks (OTN): G.709OTN frameh h

Overhead bytes: OPU, ODU, OTU OH (16 bytes x 4) and FEC OTU-OH Size: 4080 bytes * 4 rows

h

Data are transmitted in a serial basis

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Optical Transport Networks (OTN): G.709Bit rates:h h h

2,666,057.143 kbit/s optical channel transport unit 1 ( OTU1) 10,709,225.316 kbit/s optical channel transport unit 2 (OTU2) 43,018,413.559 kbit/s optical channel transport unit 3 (OTU3)

Frames periodh h h

20.420 kHz (48.971 ms) for OTU1 82.027 kHz (12.191 ms) for OTU3 ( ) 329.489 kHz(3.035 ms) for OTU3

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OTU frame: Overhead (OH)OUT frames: Overhead (OH) bytes

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OTU frame: Overhead (OH) (OH)ODU-OH: 14x3 bytes

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Tandem Connection Monitoring (TCM)4It has been defined to monitor a segment of a path carried by other carrier (carriers carrier)h

Tandem Connection

TMC1 is used by the user to monitor QoS TCM2 is used by the first carrier to monitor end-to-end QoS TCM3 is used to monitor inside the domain TCM4 is used for protection purposes by carrier B

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T. P. Walker, Optical Transport Network (OTN) tutorial

Optical Internet

OPU frame: Overhead (OH)h

OPU-OH: 8 bytes PSI (Payload Structure Identifier): identify the type of client signal

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OUT frame: Overhead (OH)h

OTU-OH: 7 bytes S SM (Section Monitoring): it allows the Section (Sec o o o g) a o s e Sec o monitoring

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Overhead bytesOverhead bytes (OMS-OH and OTS-OH) are carried by using the OSC (Optical Supervisory Channel), for which g ( p p y ), a dedicated wavelength is used (ITU-T G.872)h

h

The OSC signal is terminated at each node to carry out the monitoring functions Data channels are carried in a transparent way

For the transmission of overhead OCh-OH bytes:h

2 technological solutions :Associated Channel: A supervisor channel for each OCh Common Channel: A unique supervisor channels for many OChs

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G.709: FEC Implementation5Based on Reed-Salomon(255, 239) code to generate redundant information to be transmitted with the own client informationh

1 byte of OH and 238 data bytes are used to compute a FEC block of 16 bytes 16 FEC blocks for each row of the frame

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5G.

Barlow, A G.709 Optical Transport Network Tutorial, Innocor Ltd.

Optical Internet

FEC benefits for the optical transmissionOA Transceiver P0[dBm]: Optical power emitted [nm]: Lambda [nm]: linewidth RB [b/s]: bit rate Fiber [dB/km]: Attenuation D [ps/nmkm]: Dispersion OA Receptor OA

SR [dBm]: Sensitivity BER

P0 L SR T = D L36 10/12/2008

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FEC benefits for the optical transmissionCost reductionThe optical power required for a certain VER is lower with respect to the case without FEC5

BER Q

1 Q erfc 2 21 0 1 + 0

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5G.

Barlow, A G.709 Optical Transport Network Tutorial, Innocor Ltd.

Optical Internet

ConclusionsTechnology which allows to carry different client signals transparentlyh

OAM funtionalties

Standard technology OTN-based equipments already in the market Open issues:Control Plane for OTN (GMPLS) OMS supervision OH bytes transmission38 10/12/2008

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OutlineIntroduction to RPR technology Dynamic Packet Transport (DPT) IEEE 802.17 RPR Ethernet over ring offers a simpler and inexpensive solution for data traffic:However, because Ethernet is optimized for point-to-point or meshed topologies does not make efficient use of available bandwidth and, does not take advantage of the ring topology to implement a fast protection mechanismOptical Internet

Evolution trend (III)RPR technology advantages:increases bandwidth efficiency by implementing the spatial reuse of bandwidth Reduces costs and complexity by eliminating intermediate layers between the IP layer and the Optical layer RPR equipments should be less expensive than SONET/SDH equipment Enables services integration by supporting traffic priorities Overcomes the limitations that TDM/circuit-based architectures impose on data communications allowing direct connectivity without circuit provisioningOptical Internet

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Perspective of RPR in the MANPre-standard proprietary solutionsLantern Networks: ROPR- Resilient Optical Packet Ring p g Luminous Networks: RPT- Resilience Packet Transport Cisco Systems: DPT- Dynamic Packet Transport NORTEL Networks: OPE- Optera Packet Edge Dynarc: DTM-Dynamic Transfer Mode Appian: ODP-Optical Data Protection

Optical Internet

IEEE 802.17 RPR: Class of ServicesSupported Classes of Service:Class A: It provides low jitter transfer of traffic up to its allocated low-jitter rate. Traffic above the allocated rate is rejected. Class B: It provides bounded delay transfer of traffic at or below the committed information rate (CIR) and a best-effort transfer of the excess information rate (EIR) data beyond the committed rate. Class C: it provides best-effort traffic transfer

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IEEE 802.17 RPR: MAC datapath entityRPR MAC datapath:Frame received i checked against bit errors and ttl expiration F i d is h k d i t d i tiClientcontrol frames Shape C Shape A control filter West PHY check adjust transit A transit B/C East PHY Shape B

Optical ringlet 0

ringlet 1

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OTN Class