optical networks evolution

Optical NetworksEvolution

Optical NetworksEvolution

2N+I_2k © 2000, Peter Tomsu 02_onw_evol

Evolution of Optical NetworksEvolution of Optical Networks

Greater Network Scale

Improved Costs

Requisites Traffic Continues to Grow Reducing Networking Costs

Is A Priority

Multi-Wavelength Transmission

Multi-Wavelength Networking

Single Wavelength

Transmission


Single Wavelength Transmission

Single Wavelength Transmission

• Long haul traffic aggregation

Narrowband traffic

Reliable transmission

Efficient tributary access

• Service level switchingIsolated knowledge

“Dumb pipes”

1 Wavelength Per Fiber1 Wavelength per Network Element

ElectronicMultiplexing

ElectronicRegeneration

SDH-MUX SDH-MUX


FOTSTDMMUX1545 1550 1555

Wavelength (nm)

OC-3/12

Tx

OC-48/192

TDMMUX

ByteInterleave

Rx

Rx

Rx

Rx

• Single wavelength per fiber

• Multiple channels per fiber

• Sync and async signals are muxed to a single higher optical bit rate

• E/O signal conversion

Signals are multiplexed in the time domain Composite Optical Signal

TDM TransmissionTDM Transmission


SONET Optical Carrier (OC) and SDH Synchronous Transport Module (STM) Levels

SONET Optical Carrier (OC) and SDH Synchronous Transport Module (STM) Levels

Optical Level

Optical Level

Electrical Level

Electrical Level

Line Rate (Mbps)

Line Rate (Mbps)

Payload Rate (Mbps)

Payload Rate (Mbps)

Overhead Rate (Mbps)Overhead

Rate (Mbps)

OC-1OC-1 STS-1STS-1

OC-3/STM-1OC-3/STM-1 STS-3STS-3




OC-24/STM-8OC-24/STM-8 STS-24STS-24OC-36/STM-13OC-36/STM-13 STS-36STS-36




51.84051.840

155.520155.520

466.560466.560

622.080622.080

933.120933.120

1244.1601244.1601866.2401866.240

2488.3202488.320

4976.6404976.640

9953.2809953.280

50.11250.112

150.336150.336

451.008451.008

601.344601.344

920.016920.016

1202.6881202.6881804.0321804.032

2405.3762405.376

4810.7524810.752

9621.5049621.504

1.7281.728

5.1845.184

15.55215.552

20.73620.736

31.10431.104

41.47241.47262.20862.208

82.94482.944

165.888165.888

331.776331.776

SONET Overhead is 3% independent of Data RateSONET Overhead is 3% independent of Data RateSONET Overhead is 3% independent of Data RateSONET Overhead is 3% independent of Data Rate


ADM or DCS

ADM or DCS

Multiplex Section Multiplex Section

Multiplex Section

Termination

PTE (ADM,

DSLAM,…

PTE (ADM,

DSLAM,…

PTE(ADM,

DSLAM,…

PTE(ADM,

DSLAM,…

Service (E1, E3…)Mapping Demapping

Path

Path Termination

PathTermination

Service (E1, E3…)Mapping

Demapping

Regenerator Section

RegeneratorSection

Termination

RegeneratorSection

Termination

REG REG

PTE = Path Terminating ElementMUX = Terminal MultiplexerREG = RegeneratorADM = Add/Drop MultiplexerDCS = Digital Cross-Connect System

SDH Components andOverhead Layers

SDH Components andOverhead Layers

Regenerator Section


Total STM-1Transmission Overhead

9 Rows x 9 Columns

STM-1 AUG (261 Byte/Columns)

RegeneratorSection Overhead

(3 Byte/Rows,9 Columns)

MultiplexSection Overhead

(5 Byte/Rows,9 Columns)

A1A1 A1A1 A1A1

xx

xx

B2

x

x

x

xx

xx

B1B1

D1D1

B2

x

x

x

B2

D7

D10

S1

xxD4

1

2

Order ofTransmission

The Basic Building Block of SDH: STM-1

The Basic Building Block of SDH: STM-1

A2A2 A2A2 A2A2

xx

xx

x

x

x

M1

xx

xx

E1E1

D2D2

x

x

x

x

K1

D8

D11

x

xxD5

J0J0 xx xx

xx

xx

x

x

x

x

xx

D2D2

F1F1

D3D3

x

x

x

x

K2

D9

D12

E2

xxD6

AU Pointers

J1J1

B3B3

C2C2

F2F2

F3F3

K3K3

N1N1

H4H4

G1G1

Path Overhead1 Row x 9 Columns

APS Signaling

Section Trace

Bit Errors

Path Signal Label

• Basic building block: SDH STM-1 frame9 columns of SDH transmission overhead (x9, byte rows) = 81 bytes261 cols of STM-1 “administrative units group (AUG)” (x9, byte rows) = 2349 bytes125 microseconds/frame = 155,52 (150,34) mbps


POS Standards Based Encapsulation

POS Standards Based Encapsulation

Telcordia GR-253 ITU-T G.957ITU-T G.958

PPP in HDLC Like Framing, IETF RFC 1662

Section +Line OH

Section +Line OH

Path OHPath OH Concatenated Payload

Concatenated Payload

Flag8

Address8

Control8

PPP Packet FCS16/32

Flag8

Point-to-Point Protocol, IETF

RFC 1661

Packet over SONET/SDH, IETF RFC 2615


POS Provides Fast Restoration

POS Provides Fast Restoration

Protection switching - ADMSupport both SONET APS and SDH MSP protocols

Protection for port, LC or chassis

Protection Switching - DWDM

Optical protection protects transmission infrastructure

Layer 3 provides path restorationOpportunity for differentiation at the service level (Load-Balancing & MPLS-TE)

ProtectRouter

WorkingRouter

Cisco’s Protect Group Protocol via IP

SONET APS signaling protocol (K1/K2 BYTES)

ADM

TX

RX

Optical Cloud


POS ApplicationsPOS Applications

• Connect to tributary interfaces on SONET/SDH muxes (OC3c/STM1c to OC48c/STM16c)

• Connect to transponders in a WDM system (typically OC12c/STM4c or OC48c/STM16c)

• Interconnect GSR directly over dark fiber

with regenerators to extend the distance of LR interfaces (typically OC48c/STM16c)

within a POP (typ. OC3c/STM-1 or OC-12c/STM-4c)

Backbone Routers

Edge Routers


DPTRing

• Eliminate SONET/SDH equipment while retaining benefits

• Destination stripping

• Bandwidth consumed only on traversed segment

• No dedicated restoration bandwidth

• Dynamic, per-packetspatial reuse

• Control via SRP-fa instead of token passing

Dynamic Packet Transport (DPT)

Dynamic Packet Transport (DPT)

Working BFPWorking BFP


• New layer 2 MAC technology SRPSRP

Spatial Reuse ProtocolSpatial Reuse Protocol Uses SONET/SDH framing

Bandwidth efficient

Fairness (SRP-fa)

Scalable

Fast protection switching and service restoration

Multicasting and priority (CoS)enables DPT functionality

Spatial Reuse ProtocolSpatial Reuse Protocol

……MACMAC IP PacketIP PacketMACMAC IP PacketIP Packet

Section plus Line Overhead

Section plus Line Overhead

PathOver-head

PathOver-head



TTLTTL RIRI DSDS PRIPRI

ModeMode UsageUsage PP

Destination AddressDestination Address

Source AddressSource Address

Protocol TypeProtocol Type

PayloadPayload::::

::::

FCSFCS

SONET/SDH Frame

MAC Frame

DPT Packet Format


• DPT fairness algorithm

Distributed algorithm

Propagates and uses MAC usage info

Rate controlsfor sourced andforwarded traffic

Rapid adaptation and convergence

Transitive control

DPT Fairness ExampleDPT Fairness Example

(1)

(3)A

B

(2)

(4)

(4)


Sink

AABB

200Mbps

CC

200Mbps

DD

200Mbps

EE

200Mbps

622Mbps

155Mbps155Mbps155Mbps155Mbps

DPT-fa Operation ExampleDPT-fa Operation Example


Layer 3 SwitchingLayer 3 Switching

SRP MAC LayerSRP MAC Layer

Rx Fiber

Tx FiberRx Fiber

Tx Fiber

Rx QueuingRx Queuing Tx QueuingTx Queuing

Transit BufferTransit Buffer Tx QueueTx QueueRx PacketsRx Packets

DPT FeaturesDPT Features

(1)(1)

(3)(3)

A

B

(2)(2)

(4)(4)(4)(4)

Fiber CutFiber Cut

Detects Alarms and Events

and Wraps Ring ~100 ms

SRP Fairness Algorithm

Intelligent Protection Switching

DPT Packet Processing


DPT Cooperates With Layer 3 CoS to Extend Functionality

DPT Cooperates With Layer 3 CoS to Extend Functionality

• Layer 3 provides rich functionality and granular controls• MAC provides speed and simplicity• Enables low delay/jitter for voice and video packets

Layer 3—IPLayer 3—IP

Layer 2— SRP MACLayer 2— SRP MAC

Precedence Setting Rate Control

Congestion ControlRED/WRED

Granular SchedulingDRR on Eight Classes

Big Fat Pipes

High-Priority Bypass

Low-Priority Fairness

Precedence Mapping


BackboneBackbone

~~~~~~WDMWDM~~~~~~

GSRGSR

GSRGSR

BuildingAccess

Mux

PacketConcentrator

2.4G MetroAccess

Ring

10Gb RegionalTransport

Ring

10Gb RegionalTransport

Ring

Cable Data Ring

Network Architecture MigrationNetwork Architecture Migration

SiSi

SiSi

Dedicated AccessPoP Ring

LeasedLines

GSRGSR

GSRGSR

SiSi



Single Wavelength

Transmission


Improved Costs




DWDM System DesignDWDM System Design

1550

1551

1552

1553

1554

1555

1556

1557

01234567

01234567

Amplify DW

DM

Filt

er

Op

tic

al C

om

bin

er

15xx nm 1310 nmReamplifyReshapeRetime

Rx Tx1310 nm

Rx

Ex

tern

al

Mo

du

lato

r

Laser

15xx nm


Optical IP - using WDM

1550

1551

1552

1553

1554

1555

1556

1557

0

1

2

3

4

5

6

7

TransmitReceive 3R

1550

1551

1552

1553

1554

1555

1556

1557

0

1

2

3

4

5

6

7

Transmit Receive 3R

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

20 ppm

50 ppm

PLL

50 ppm

PLL

LOOPTIMING


Multi-Wavelngth TransmissionMulti-Wavelngth Transmission

• Fiber exhaust due to traffic growth

Increased data use

Higher data rates

• Enabling technologiesDWDM - fiber savings

EDFAs – regenerator savings

• Transparent fiber aggregation

“Virtual Fiber”

“N” Wavelengths Per Fiber1 Wavelength per Network Element

.

.

.

.

.

.


DWDM Transmission

OC-48 x 40 ch. = 100 G/bsOC-192 x 16 ch. = 160 G/bsOC-48 x 80 ch. = 200 G/bs

Composite Optical Signal

Wavelength (nm)

OC-48/192

WDMMUX

TxRx

TxRx

TxRx

TxRx

1530 1550 1565

Signals are multiplexed in the wavelength domain

• Multiple wavelengths per fiber

Multiple channels per wavelength (TDM)

Statistically multiplexed data traffic

• No signal format conversion


ITU Wavelength GridITU Wavelength Grid

• ITU-T grid is based on 191.7 THz + 100 GHz

• Its purpose is to standardize lasers not DWDM systems

• There is no standard for DWDM systems

Number and spacing of s are design variables

1530.33 nm 1553.86 nm

0.80 nm


EDFA SchematicEDFA Schematic

...

...

980PumpLaser

WDMCoupler

WDMCoupler

EDF

DCF

OpticalIsolator

1480PumpLaser

OpticalFilter

OpticalIsolator

EDF

• EDFAs amplify all s in 1550 window simultaneously

• Key performance parameters include

Saturation output power, noise figure, gain flatness/passband


Anatomy of a DWDM System

Terminal A Terminal B

Post-Amp

Pre-Amp

Line Amplifiers

MUX

DEMUX

TransponderInterfaces

TransponderInterfaces

DirectConnections

DirectConnections

Basic building blocks• Optical amplifiers• Optical multiplexers• Stable optical sources


Basic Optical ProtectionBasic Optical Protection

• Protection migrates to DWDM equipment

Only 1 DWDM with protection modules needed

Switching decision controlled by transponders

Technologies include optical switching and OA gating

Working

Protect


DWDM State-of-the-artDWDM State-of-the-art

Data

Rate

• Point-to-point systems

40 x OC-48 deployed

16 x OC-192 deployed

160 x OC-192 announced

• Configurable OADMs

• Metro rings

1-10 Tbps per fiber is just around the corner!1-10 Tbps per fiber is just around the corner!



Single Wavelength

Transmission


Improved Costs




.

.

.

.

.

.

“Virtual Transport”

Multi Wavelength NetworkingMulti Wavelength Networking

• Network and operations scaling v.S. Raw capacity

Single wavelength elements not keeping pace

Operations need to scale

• Enabling technologiesScalable and ultra dense architectures of electronic

Networking intelligence

“N” Wavelength Per Fiber“N” Wavelength per Network Element


Moving From Static to Intelligent

Moving From Static to Intelligent

TraditionalStatic

TransportNetwork

Point-to-Point WDMPhysical Transport Overlays

Static ProvisioningLimited Line Rate

Linear or Ring Protection

Reduces total Cost of Ownership

IntelligentOptical

TransportNetwork

Intelligent Optical NetworksVirtual Transport Networks

Dynamic ProvisioningFlexible Capacity

Flexible Protection


Emergence Of Intelligent Optical Core

Emergence Of Intelligent Optical Core

Layer 3IP

Layer 2ATM

Layer 1Voice/

P.L.

DistributedIntelligence

Provisioning &IntelligentGrooming

Full Suite ofProtectionMethods

Scalable and Granular Capacity STM-1 to Wavelengths


Next Generation Optical Protection

Next Generation Optical Protection

• Protection controlled by large cross-connects on tributary side of DWDM running a routing protocol

• Protection migrates from fiber to level

• Line, ring and mesh restoration options


Flexible & Rapid RestorationFlexible & Rapid Restoration

• Restore virtual wavelength paths end-end in 50ms using a wavelength routing protocol

• Linear, ring & mesh options

• No preplans, no dedicated restoration bandwidth

• Wavelength routing protocol will be very similar to IP+ATM MPLS approach

Multiprotocol Lambda SwitchingMultiprotocol Lambda Switching


All Optical NetworkingAll Optical Networking

• Optical dial tone

O-E sub-systems present only at network end points

• Potential for cost savings

No more equipment upgrades?

• Enabling technologies:

Lower cost optical systems

Ubiquitous compliance to optical standards

Optical OAM&P

No need for granular capacity

Multi-WavelengthNetworked

Transparent Services

FabricFabric

FabricFabric


Optical CrossConnect with Full Wavelength Conversion

Optical CrossConnect with Full Wavelength Conversion

• M demultiplexers at incoming side

• M multiplexers at outgoing side

• Mn x mn optical switch has wavelength converters at switch outputs

1,2, ... ,n

1,2, ... ,n

1,2, ... ,n

1

2

m

Optical CrossBarSwitch

WavelengthConverters

WavelengthMux

WavelengthDemux

1,2, ... ,n

1,2, ... ,n

1,2, ... ,n

.

.

.

.

.

.

12n

12n

12n

1

2

n

12n

n12

1

2

m


1,2, ... ,n

in


1,2, ... ,n1

2

n1

2

nout

Add-Ports Drop-Ports

Optical CrossBarSwitch

WavelengthDemux



1 2 n 1 2 n

Optical Add/Drop MultiplexerOptical Add/Drop Multiplexer

• OADM similar to OXCuses only 2 trunk ports

uses remaining incoming ports as Add-ports

uses remaining outcoming ports as Drop-ports1

Trunk port Trunk port

1,2, ... ,n 12n

1,2, ... ,n1

2

noutin


Wavelength RoutingWavelength Routing

• Streamline layers, remove functional overlap

• Deliver optical transport and traffic-engineering at wavelength level complementing IP, MPLS

• New functionsRapid end-to-end provisioning

Fast path restoration

Bandwidth efficiencies

Questions ???Questions ???

optical networks evolution

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