ROADM Network Elements

Transcript ROADM Network Elements

ROADM Network Elements

Brandon Collings

Optical Networks Research, JDSU

OFC 2007 OThR1

Overview

     Market Drivers for ROADM Networks Primary ROADM Network Features  ROADM Node Building Blocks and Node Architectures Physical Layer Operational Features and Automation  ROADM Component Characteristics and System Performance Network Management Current and Future Trends

Market Drivers for ROADM Networks

Bandwidth is increasing…

  Capacity increase is significant But the real story is how that capacity is evolving…

Drivers of the Today’s All Optical Networks

Triple Play Services Rich Media Services

US HQ 5

Tokyo

Business Services

Consumer Driven Applications



Content and bandwidth is evolving in a peer-to-peer topology Bandwidth is increasing and predictability decreasing

Downloading TV programs from the Web is becoming more popular with consumers. There was a 39% increase in subscription rentals of TV content and a 255% increase in TV-title digital video downloads between August 2005 and August 2006. (NPD Group)  In December 2006, Xbox Live surpassed 4 million members worldwide. Microsoft expects it to surpass 6 million members by the summer of 2007.

 According to YouTube, it is currently serving 100 million videos per day, with more than 65,000 videos being uploaded daily.

 In January of 2007 Apple announced that more than two billion songs, 50 million television episodes and over 1.3 million feature-length films have been purchased and downloaded from the iTunes Store

Rich Media Services Have Changed the Network Model The “Telephony Network”

    Sonet-SDH network Bandwidth predictable Traditional usage voice, dial-up Low bandwidth, low use and short duration

The Agile Optical Network

    DWDM Network High bandwidth applications Always-on Unpredictable traffic and growth patterns

Market Overview : Technology Trends

$900 $800 $700 $600 $500 $(M) $400 $300 $200 79% $100 $ 2004 21% Agile + Fixed CAGR = 19% 39% Rapid Transition from Fixed to Agile Agile CAGR = 55% 61% 2005 2006 2007 2008 Agile Fixed

Source: Ovum-RHK, Transition to agile optical network drives ROADM and related modules growth, 2/2006 CAGR data is 2004-2010

The Agile Optical Network is Happening Today

“While not everyone has announced their deployment of Agile Optical Networks, most are using them in some form or fashion”

Brett Azuma Exec VP, Ovum-RHK

Primary ROADM Network Features

Let’s just get this out of the way…

Unsuccessful Business Case

COST!

Successful Business case in some market segments A Technology and Manufacturing Challenge

Static Networks Based on Fixed-Wavelength Filters

  Topology and capacity/node determined at time of network design – Traffic projections based upon best estimates at the time – Frequently changes even during design/bid/deployment – Not always cost effective to “overbuild” the system Can lead to premature system exhaust – Expected system lifetime: 5-10 yrs – Traffic projections not accurate leading to premature system exhaust • Insufficient l ’s available to hot spots • Unlit l ’s to cold spots cannot be utilized – Topology is inconsistent for emerging applications • Telephony, SAN, Enterprise, VoD, TBD topologies look different

Ch 1-8 Ch 9-16 Ch 17-24

Hub

Ch 1-32 Ch 25-32

Physical WDM Ring

ROADMs Enable Any-Node-to-Any-Node Topologies

  Provision wavelengths independently between nodes No blocking extends system life to capacity limitation – Relieves need for accurate traffic growth forecasting (2x1 Switch+VOA) Array

TAPs & PD Arrays ROAM ADD CHANNELS VOA Tap PD DEMUX ROADM ROADM TAP & PD Array DROP CHANNELS Demux-T ROADM ROADM ROADM

Physical WDM Ring

All Optical Ring Interconnect Reduce OEO Costs

ROADM ROADM ROADM ROADM ROADM ROADM

     Ring-to-Ring traffic previously electrically cross-connected – Required O/E transponders on both rings – Requires electrical switch and grooming fabric Multi-Degree ROADM Nodes enable inter-ring traffic to remain in the optical domain – Removes cost of OEO and electrical fabric ROADM Nodes capable of remotely routing full capacity of channels without additional equipment – OEO transition requires additional equipment with each wavelength – Electrical switching fabrics generally not as scalable Traffic can be routed without craft visit to node ROADMs are bit-rate independent – Implement higher line rates when, where and if the economics prove in

All Optical Ring Interconnect Reduce OEO Costs

ROADM ROADM ROADM ROADM ROADM ROADM ROADM

Accelerated Service Roll-out

 Remote provisioning and automated control plane enable more rapid service commissioning – Shorter Time-to-Revenue and Return on Investment – Increased customer capture – Shorter and predictable deployment intervals – Network topology flexibility reduces network configuration churn

ROADM Node Building Blocks and Node Architectures

Four Basic Types of ROADM Components

Tunable Channel Filter Tunable Band Filter Wave Blocker (WB) PLC ROADM Wavelength Selectable Switch (WSS)

Typical Tunable Channel Filter Node Architecture

From West Coupler Coupler OA OA Tunable Filters Wave Blocker Receivers Transmitters

    

DROP ADD

Independent access to all wavelength channels – Number of Add/Drop ports less than maximum wavelength count Tx/Rx ports are wavelength provisionable (colorless) Supports drop and continue – Waveblocker required for wavelength reuse Add channels power equalized – Express channels equalized if WaveBlocker included Supports 2-degree nodes

To East

Typical Tunable Band Filter Node Architecture

From West OA Band Filter AWG Band Filter AWG OA To East Receivers 20 DROP

      Channels added/dropped in bands – Width of bands may be fixed or adjustable – Band is tunable in wavelength Tx/Rx ports are wavelength specific (colored) Wavelengths may be reused Add channels power equalized Does not support drop and continue Supports 2-degree nodes © 2007 JDSU. All rights reserved.

ADD Transmitters

Typical WaveBlocker Node Architecture

From West OA Coupler Block Wave Blocker Coupler AWG OA To East AWG Receivers Transmitters DROP ADD

     Independent access to all wavelength channels Tx/Rx ports are wavelength specific (colored) Express and Add channels are power equalized Supports drop and continue Supports 2-degree nodes

Typical PLC ROADM Node Architecture

From West OA Coupler PLC ROADM OA To East AWG Receivers DROP

    Independent access to all wavelength channels Tx/Rx ports are wavelength specific (colored) High level of integration – Add direction wavelength multiplexing – Per channel power monitoring (Add and Express) – Add and Express channel power equalization – Express or Add channel selection Supports 2-degree nodes

ADD 22

Transmitters

PLC ROADM Block Diagram 23

Mux and Demux WSS Node Architecture

From West OA WSS WSS OA To East Receivers Transmitters

    

DROP ADD

Independent access to all wavelength channels – Number of Add/Drop ports less than maximum wavelength count – Cascade secondary WSS components off primary WSS for additional ports Tx/Rx ports are wavelength provisionable (colorless) Express, Add and Drop channels power equalized Does not support drop and continue Supports 2-degree nodes

Demux WSS Node Architecture

From West OA WSS Coupler Coupler OA To East Receivers Transmitters

    

DROP ADD

Independent access to all wavelength channels – Number of Add/Drop ports less than maximum wavelength count – Cascade secondary WSS component off primary WSS for additional ports Tx/Rx ports are wavelength provisionable (colorless) Express, Add and Drop channels power equalized Does not support drop and continue Supports 2-degree nodes

Multi-Degree WSS Node Architectures

North In Demux 1xN WSS Mux Nx1WSS North Out South In South Out East In East Out West In West Out

   Replace Demux WSS with power splitter output degrees Mux WSS selectively accepts wavelengths Mux WSS selectively accepts wavelengths intended for its intended for its respective degree respective degree – Provides isolation for those wavelengths not intended for its respective degree © 2007 JDSU. All rights reserved.

Multi-Degree Demux WSS Node Architecture

North Rx Rx Rx Rx Tx Tx Tx Tx West OA WSS OA Coupler Coupler Coupler East OA WSS ADD OA ADD Tx Tx Tx Tx Rx Rx Rx Rx DROP South 27

Characteristics of Multi-Degree Demux WSS Architecture

     Supports any wavelength from any degree to any degree Drop port count limitations due to port sharing with inter degree connections Add/drop ports are colorless – No add port filtering rejects rogue wavelengths or noise Does not support drop and continue Drop and express channel equalization provided by WSS – Add port VOAs provide add channel equalization

Tx Tx Tx Tx Rx Rx Rx Rx South 28

Multi-Degree Mux WSS Node Architecture

North Rx Rx Rx Rx WSS Tx Tx Tx Tx West OA OA Coupler AWG Rx Rx East OA AWG Coupler ADD AWG OA Tx Tx Tx Tx ADD WSS Rx Rx Rx Rx DROP South 29

Characteristics of Multi-Degree Mux WSS Architecture

     Supports any wavelength from any degree to any degree Add/drop ports present for all supported channels Add/drop ports are colored – Add port filtering rejects rogue wavelengths Supports drop and continue Add and express channel equalization provided by WSS – No per channel power control on drop ports (unless VOAs included)

Tx Tx Tx Tx WSS South Rx Rx Rx Rx 30

Multi-Degree Mux and Demux WSS Node Architecture North Rx Rx Rx Rx Tx Tx Tx Tx West OA OA Coupler WSS WSS DROP WSS East OA Coupler ADD WSS OA ADD Tx Tx Tx Tx Rx Rx Rx Rx DROP South 31

 

Characteristics of Multi-Degree Mux and Demux WSS Architecture

  Supports any wavelength from any degree to any degree Drop port count limitations due to port sharing with inter degree connections  Add/drop ports are colorless – Add port filtering rejects rogue wavelengths and noise Supports drop and continue Add and express channel equalization provided by Mux WSS – Demux WSS provides drop channel power control

Tx Tx Tx Tx Rx Rx Rx Rx South 32

Optical Layer Architectural Feature Comparison

33 Feature East/West Node Equipment Separability Add/Drop with Channel Granularity Access to Any Combination of Channels Add/Drop Port Count Equal to Channel Count Non-service Affecting Upgrades Drop and Continue Equalization of Expressed Channels Add Channel Rogue Wavelength Protection Add Channel Power Control Drop Channel Power Control Colorless ports Mesh Topology/Higher Degree Node Support Tunable Filter

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O O O



O O Wave Blocker

        

PLC

    

  

WSS (Mux)

        



WSS (DMx)

  



Intrinsically Supported O Support depends upon particular configuration or inclusion of specific elements (i.e. VOA’s) Not Supported

Physical Layer Operational Features and Automation

ROADM Network Operational Features and Automation

    Reconfigurability requires visibility into the optical layer and automated control – Monitor wavelength routing – Monitor optical layer performance – Provide feedback for channel power adaptation Automated optical layer eases installation and operational activities – Quicker, cheaper, more predictable installation intervals – Reduces required craft training and in the field measurements – Minimizes complex activities such as power measurement and balancing – Neighbor node and configuration discovery – Minimizes errors – Provides fault correlation Automated control enables increased performance and reliability – Longer system reach due to channel power equalization – Increased adjustment accuracy than possible manually – Performance monitoring and early warning alarms Simplifies support for alien wavelengths

Optical Layer Monitoring Components

 Possible Monitored Parameters – Optical channel power – OSNR – Wavelength alignment – Wavelength ID or tag  Characteristics – Measurement refresh rate – Single or multi-input (shared) – Single channel dynamic range – Adjacent channel dynamic range – Accuracy

Two Basic Types Parallel Scanning

Scanning Tunable Filter

Automatic Optical Power Management

 ROADM networks have a rich complement of power control actuators – Per channel power control at ROADMs – Total average gain control at EDFAs

Automated Channel Power Equalization

   Channel power levels become unequal – Accumulated optical amplifier gain shape – Non-uniform fiber loss – Inter-channel Raman pumping – Optical elements Added channels require leveling when introduced into system – Many transponders do not produce tightly controlled output power – Power level may not be appropriate – Insertion loss of add path can vary Feedback algorithms control both optical amplifier and per channel attenuation – Optical amplifiers operate on all channels – Goal is to minimize amplifier gain – Minimizes OSNR degradation

Channel Power Level Transient Timescales

~2ms min/hour/day/year

Long Term Effects Spectral Hole Burning EDFA Transient

change in channel loading and/or channel count •EDFA reacts to maintain •Fiber loss aging •Gain spectrum changes due to failure l

sat

•Rapid decrease in input power l

sat

•PDL •Laser aging

Holes at

l

sat

positive or negative channels Srivastava et al, OFC 1995

Reaction Rate of Power Control

  Power Measurement (Optical Channel Monitor) – Parallel techniques: capable of sub-millisecond – Scanning techniques: 10’s of ms to seconds • Technology dependent – Multi-Input OCMs • Utilizes high isolation Nx1 selection switch • Decreases refresh rate by >N times Attenuation Change Actuation – VOAs: typically on the order of milliseconds – ROADMs: several milliseconds to seconds • Technology and magnitude of attenuation change dependent

Power Level Transient Mitigation

   Transient suppression in the EDFA – ROADM and VOA reaction rates currently insufficient Gain change due to SHB requires ROADM attenuation correction – Gain change is typically small per amplifier (<0.5dB) – Change to channel power can accumulate with EDFA cascade – Depending upon ROADM attenuation speeds, some channels may be “unequalized” for several milliseconds During this period, system performance may be impacted – Duration is sufficient to trigger protection switch if impact is sufficiently severe – System design concern on extent to which system reach can be extended by capitalizing on channel power equalization

Commissioning/Decommisioning

  Intentionally slow introduction and removal of optical power during network activities – Channel installation or removal – EDFA installation or removal – Fiber connection or disconnection Power control algorithms can react and keep system in equilibrium

ROADM Component Characteristics and System Performance

Cascading ROADM Nodes

 Details of the channel filtering become significant as number in cascade increases – Amplitude Response • Wide, flat top shape required – Phase response • • a.k.a group delay which causes dispersion Group delay ripple and structure must be minimized – PMD  Channel spacing and Bit Rate – 10Gb/s typically not significantly impacted – 40Gb/s over 50GHz ROADMs has been deployed • Using advanced modulation techniques

Typical WSS-based Node and Port Isolation

Degree 1 Degree 2

AWG AWG

…what happens to l i in WSS?

l i,port_1 from deg 1 port isolation (PIso) port selected to pass l i,port_2 from deg 2 l i,port_3 from deg 3 l i,port_4 from deg 4 l from deg m-1 i,port_m-1 l i,add from add Output (at l i ) is coherent combination of l i,port_2 along with m 1 l i signals, each suppressed by PIso Degree m-1

AWG 45

AWG

OSNR Penalty versus Port Isolation

  Assumes nominal attenuation of 4 dB for channel power equalization N is the number of interfering signals present 3 2.5

2 1.5

N=8 N=16 N=24 N=48 N=64 1 0.5

0 35 37.5

40 42.5

WSS Port Isolation, PIso [dB]

47.5

Network Management

 Physical Layer Configuration Discovery – Inventory – Adjacent nodes – Intra-node element interconnection verification   Wavelength Routing Verification Performance Monitoring – Full visibility into active wavelength performance – Threshold crossing warnings and alarms  Alarm Correlation – Prioritize alarm closest to root cause – Suppress other alarms resulting from fault condition

Current and Future Trends

Current and Future General Trends

     Increased Component Integration – Reduce cost through circuit pack consolidation Increased Use of Open Photonic Layers – Improving physical layer automation increases acceptance criteria for non-native (alien) wavelengths – IP migration and proliferation of pluggable DWDM interfaces ROADMs Penetrating Edge/Access – Highly cost sensitive – Perhaps most rapidly evolving network space Enhanced In-situ Diagnostics – Link performance and engineering rules validation – Fiber plant characterization (dispersion, PMD, etc.) Increased utilization of topology flexibility and wavelength tunability – Restoration and disaster recovery – Load balancing – Protection switching

ROADM Network Elements

Transcript ROADM Network Elements

ROADM Network Elements

Brandon Collings

Optical Networks Research, JDSU

Overview

Market Drivers for ROADM Networks

Bandwidth is increasing…

Drivers of the Today’s All Optical Networks

Market Overview : Technology Trends

The Agile Optical Network is Happening Today

Primary ROADM Network Features

Let’s just get this out of the way…

COST!

All Optical Ring Interconnect Reduce OEO Costs

All Optical Ring Interconnect Reduce OEO Costs

Accelerated Service Roll-out

ROADM Node Building Blocks and Node Architectures

Four Basic Types of ROADM Components

Typical Tunable Channel Filter Node Architecture

Typical Tunable Band Filter Node Architecture

Typical WaveBlocker Node Architecture

Typical PLC ROADM Node Architecture

Mux and Demux WSS Node Architecture

Demux WSS Node Architecture

Multi-Degree WSS Node Architectures

Multi-Degree Demux WSS Node Architecture

Multi-Degree Mux WSS Node Architecture

Optical Layer Architectural Feature Comparison

Physical Layer Operational Features and Automation

Optical Layer Monitoring Components

Automatic Optical Power Management

Automated Channel Power Equalization

Channel Power Level Transient Timescales

Reaction Rate of Power Control

Power Level Transient Mitigation

Commissioning/Decommisioning

ROADM Component Characteristics and System Performance

Cascading ROADM Nodes

Typical WSS-based Node and Port Isolation

OSNR Penalty versus Port Isolation

Network Management

Network Management

Current and Future Trends

Current and Future General Trends

Thank You

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