Network Control in Optically Switched Networks

Jun He

November 28, 2011

Overview

• Physical Impairment Aware Routing and Wavelength Assignment in Optically Switched Networks

• Intelligent Aggregation Network Control and Management System for CIAN

12/5/2011 2

Outline • Introduction • Impairment aware routing and wavelength

assignment (RWA) – Impact of physical impairments – Optimal RWA with the quality of transmission

(QoT) constraint – Heuristic RWA with the QoT constraint

• Adaptive QoT-aware routing algorithm • QoT-Friendly wavelength assignment

– Analytical performance analysis

3 12/5/2011

Motivation • The dramatic increase in throughput demands from backbone

transport systems has propelled the development of all-optical networks.

12/5/2011 4

http://lw.pennnet.com/display_article/365016/13/ARTCL/none/none/1/Trans-Atlantic-bandwidth-faces-a-capacity-shortage/?cmpid=EnlDirectJune222009

Introduction

5 12/5/2011

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Past Present Future

• Evolution of optical networks

OEO router WDM fiber link Optical switch

DRAGON

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Introduction • From OEO to optical switching

– Low complexity and energy consumption – Low deployment, maintenance, and operation cost – Transparency – Bandwidth and QoS – On demand service provisioning

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DiCon's MEMS 16x16 Matrix Optical Switch

Cisco 12000 Series Router

Challenges

• Optically switched networks – New architecture, technology – Device modeling, placement – Physical impairment accumulation

• Physical impairment aware routing and wavelength assignment

– ...

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Careful design of cross-layer network control can efficiently improve the network performance in optically switched networks.

Physical impairments

• Physical impairments in optical networks – Crosstalk

• Linear and nonlinear – ASE noise from EDFA – Shot noise – Thermal noise

12/5/2011 9

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Impact of physical impairments

• Quality of transmission (QoT) – BER, delay, etc.

12/5/2011 10

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Crosstalk

• Linear – Switching – Self – Neighbor

12/5/2011 11

Crosstalk

• Linear – Switching – Self – Neighbor

• Nonlinear – FWM – XPM

12/5/2011 12

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* Y. Pointurier, et. al. "Fair QoS-aware adaptive routing and wavelength assignment in all-optical networks," in IEEE ICC, Istanbul, Turkey, Jun. 2006.

Impairment aware RWA

• Lightpath establishment – Wavelength continuity constraint – QoT constraint

12/5/2011 13

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Optimal RWA for SLE

• With QoT constraint* – Wavelength

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12/5/2011 14

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* J. He, et. al. "Optimal RWA for Static Traffic in Transmission-Impaired Wavelength-Routed Networks," IEEE Communications Letters, Vol. 12, pp: 694-695, Sept. 2008.

Practical RWA • Practical routing algorithm

– Shortest path algorithm (SP) • Efficient • Distributed • Easy to implement

• Practical wavelength assignment (WA) algorithm – First Fit (FF)

• Pick the first wavelength with lowest index • Low chance of wavelength shortage • High crosstalk level

– Random Pick (RP) • Randomly choose one of free wavelengths • High chance of wavelength shortage • Low crosstalk level

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FF WA

RP WA

Numerical results

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Opt-RWA: optimal routing and wavelength assignment (RWA)

Opt-WA: optimal wavelength assignment (WA) + shortest path routing SP-FF: not optimal

Gaps (red): performance degradation because of physical impairments

Gaps (Purple): performance improvement because of optimization

Dynamic RWA with QoT constraint • QoT aware and QoT guaranteed • Adaptive

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A request arrives

Choose a new wavelength based on wavelength assignment algorithm, such as FF or RP

Find a best available path with a chosen hop weight function for the chosen wavelength

Accept the request

Reject the request

QoT estimation for the chosen lightpath and other involved lightpaths

QoT < threshold

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Weight functions in adaptive routing • Shortest distance (SD)

– Length of link i • Fewest hop (FH)

– Constant • Q-maximizing (QM)*

– Average Q factor for existing LPs • Least variance (LV)**

– Based on noises' variance at hop i

12/5/2011 18

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* T. Deng, et. al. "Adaptive QoS routing in dynamic wavelength-routed optical networks," in IEEE Broadnets, Oct. 3-7, 2005. ** J. He, et. al. "QoT-aware routing in impairments-constraint optical networks," in IEEE GLOBECOM, Washington, DC, USA, 2007.

Simulation results

12/5/2011 19 Use BP as 2nd performance metric

QoT-Friendly wavelength assignment

• An important observation

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The crosstalk power level is wavelength dependent, with crosstalk from immediately adjacent wavelengths more powerful than crosstalk from those separated by one or more wavelengths.

Conventional first fit WA

QoT-Friendly WA Wavelength ordering RP WA

Wavelength ordering • Optimal ordering • Heuristic ordering

– Static ordering (FFwO)* • Pre-ordering: pick the next one furthest away from the ordered wavelengths • Complexity: O(nm)

– Dynamic ordering (FFwSS)** • Pick a wavelength suffered the least degradations • Complexity: O(nmW2)

– Adaptive wavelength ordering (AFFwSS)** • FFwO or FFwSS based on current network state • Complexity: O(nmW2)

12/5/2011 21

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* J. He, et. al. "QoS-Aware Wavelength Assignment with BER and Latency Constraints for All-Optical Networks," IEEE/OSA Journal of Lightwave Technology, Vol. 27, pp: 462-474, March 2009. ** J. He, et. al. "Adaptive wavelength assignment using wavelength spectrum separation for distributed optical networks," in IEEE ICC, Glasgow, UK, June 2007.

Simulation results

12/5/2011 22

FF vs RP without impairments

FF vs RP with impairments

FF vs FFwO with impairments

Intelligent Aggregation Network Control and Management System for CIAN

• CIAN projects develop or will develop control module for their components, devices, or test beds. These modules serve as drivers and define the functions and behaviors of the delivered components or sub-systems.

Thrust 2:SubsystemIntegration& SiliconNanophotonics

Thrust 1:OpticalCommunicationSystems& Networking

Rese

arch

Proj

ects

Working Group II:Intelligent Access

AggregationNetworks

Use Cases:Telepresence, 3D holographic

Video

Working Group I:Scalable

& Energy EfficientData Centers

Thrust 3:Materials& Devices

Rese

arch

Proj

ects

Rese

arch

Proj

ects

Packaging & TestUA

Optical Aggregation Testbed (TOAN)

UA

Data CenterTestbed (SEED)

UCSD

Use Cases:Efficient Data centersYou Tube, Facebook

Chip scale Testing

UA and UCSD

DataIntrospection

USC

Cross-layerOptimization

Columbia

Network IntegrationUCSD

Optical Device Characterization

UA

Financial Enterprise

….. Broadband & Triple Play

Wireless Backhaul

Business Services

WDM

MSPP

Ethernet-Switched Packet Network

SONET/SDH, OTN Transport Network

PacketONP

PacketONP

PacketONP

PacketONP

MSPP

PacketONP

PacketONP

PacketONP

PacketONP

…..

TOAN Regime Core Transport Customer Premises

Aggregation Platform: Packet & TDM Svcs. + Optical transport

CIAN Cross-Layer Box Ethernet SONET WDM

Metro Aggregation Regional & Long Haul

Research Challenges

• How to glue heterogeneous components and sub-systems

• How to add the intelligence to the CIAN network

Current Architecture

• A centralized management and control protocol above TCP/IP in application layer – An initiating entity (CMS

software) opens a Transmission Control Protocol connection to the receiving entity (FW nodes or OPM devices) before it sends/receives info with the receiving entity.

– The parties then maintain that TCP connection for as long as the network elements are in use.

Experimental Setup • Proof-of-concept control and management

experiments (CIAN CMS) in CIAN TOAN testbed – Integrate TL1 standard management protocol – Integrate QoT-awareness to the network

• QoT-aware lightpath switching and wavelength re-provisioning