load balancing in protection switching of optical networks hongkyu jeong, gyu-myoung lee information...

Load Balancing in Protection Switching Load Balancing in Protection Switching

of Optical Networksof Optical Networks

Hongkyu Jeong, Hongkyu Jeong, Gyu-Myoung LeeGyu-Myoung Lee

Information and Communications Univ. (ICU)Information and Communications Univ. (ICU)

Student ID : 20022130, 2000520 Student ID : 20022130, 2000520 E-mail: [email protected], [email protected]: [email protected], [email protected]

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OutlineOutline

I.I. IntroductionIntroduction

II.II. Proposed Path Selection Proposed Path Selection

MechanismMechanism

III.III.Simulation AssumptionsSimulation Assumptions

IV.IV.Numerical Results and AnalysisNumerical Results and Analysis

V.V. Conclusion and Future WorksConclusion and Future Works

VI.VI.ReferencesReferences

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IntroductionIntroduction

Traffic of multimedia data has been increasingTraffic of multimedia data has been increasingSurvivability of optical network has become one of the Survivability of optical network has become one of the pivotal issuespivotal issues

In the real world, 1+1 or 1:1 protection In the real world, 1+1 or 1:1 protection mechanism commonly has been adoptedmechanism commonly has been adopted

Resource utilization of those protection schemes is at Resource utilization of those protection schemes is at most 50% low when applied to optical networksmost 50% low when applied to optical networks

Sharing rate of backup path is noticeably lowSharing rate of backup path is noticeably low

Recently, traffic engineering concept of GMPLS Recently, traffic engineering concept of GMPLS is introducedis introduced

Improvement on network resource utilization through Improvement on network resource utilization through load-balancing is becoming the important issueload-balancing is becoming the important issue

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Introduction (cont.)Introduction (cont.)

Analyze four path selection modelsAnalyze four path selection modelsPreconfigured protection schemePreconfigured protection scheme

AssumptionAssumptionLoad is the call request to reserve wavelength Load is the call request to reserve wavelength for working path (WP) and backup path (BP)for working path (WP) and backup path (BP)

Achieve higher utilization rate of BPAchieve higher utilization rate of BPBy introducing the concept of load-balancing By introducing the concept of load-balancing where selecting policies are adopted for modelswhere selecting policies are adopted for models

Achieve 100% restorationAchieve 100% restorationBy not selecting the BP that has the WP within By not selecting the BP that has the WP within the same SRLGthe same SRLG

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Proposed Path Selection Proposed Path Selection MechanismMechanism

First, find shortest path setFirst, find shortest path setSecond, select three Second, select three disjointed shortest paths in disjointed shortest paths in the shortest path set by the shortest path set by each specific policyeach specific policy

Most shortest path is used for Most shortest path is used for WPWPIf there are call requests which If there are call requests which have same source node and have same source node and destination node pair, same destination node pair, same paths are used for reserving WP paths are used for reserving WP and BPand BP

Third, when a call request is Third, when a call request is arrived at a source node, arrived at a source node, the node finds a wavelength the node finds a wavelength for WPfor WP

Reserve or rejectReserve or rejectFig.1 Simplified flow of proposed mechanism

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Proposed Path Selection Mechanism Proposed Path Selection Mechanism (cont.)(cont.)

Fourth, nodes Fourth, nodes preferentially finds a preferentially finds a wavelength for BP which wavelength for BP which can be sharedcan be shared

If there is no sharable If there is no sharable wavelength, unused wavelength wavelength, unused wavelength is reserved for BPis reserved for BP

If there is no unused If there is no unused wavelength, the call request is wavelength, the call request is rejectedrejected

Only when it is possible Only when it is possible to reserve both WP and to reserve both WP and BPBP

Call request is accepted and Call request is accepted and wavelength reserving wavelength reserving mechanism is completedmechanism is completed

Fig.1 Simplified flow of proposed mechanism

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Simulation AssumptionsSimulation Assumptions

Find shortest path Find shortest path set from a node to set from a node to other nodeother node

Select shortest paths Select shortest paths for WP and BP by the for WP and BP by the policy of each modelpolicy of each model

For the selected For the selected model, case 1 and model, case 1 and case 2 are alternately case 2 are alternately selected as shown in selected as shown in Table 1Table 1

Case 1 Case 1 Case 2Case 2

Model 1Model 1 WP: path1WP: path1 No useNo use

BP: path2BP: path2

Model 2Model 2 WP: path1WP: path1 WP: path2WP: path2

BP: path2BP: path2 BP: path1BP: path1





Table 1. path selection policies of four different models

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Simulation Assumptions (cont.)Simulation Assumptions (cont.)

Each link capacity (W)Each link capacity (W)Unlimited in the case of evaluating sharing rateUnlimited in the case of evaluating sharing rate32 and 64 wavelengths are used to evaluate 32 and 64 wavelengths are used to evaluate the call request blocking ratethe call request blocking rate

The number of node N is 16The number of node N is 16Call request is 8*load (load is positive Call request is 8*load (load is positive integer)integer)Each node has no wavelength converterEach node has no wavelength converterWP and BP are disjointed pathWP and BP are disjointed path

When we look for a sharable wavelength for When we look for a sharable wavelength for BP, the wavelength should not be shared by BP, the wavelength should not be shared by BPs that have the WP which belongs to the BPs that have the WP which belongs to the same SRLG same SRLG

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Torus topology (Fig.2)Torus topology (Fig.2)It has not only many paths but It has not only many paths but also similar lengths (number of also similar lengths (number of nodes to be passed) from a nodes to be passed) from a source to a destinationsource to a destination

Similar characteristics which Similar characteristics which topologies in the real world topologies in the real world possesspossess

For each call requests, the For each call requests, the WP and BP are randomly WP and BP are randomly chosen from the shortest chosen from the shortest path setpath set

For each experiment we run For each experiment we run 50 times simulation, and 50 times simulation, and then take the averagethen take the average

Fig.2 A 2-dimensioinal 4X4 Torus Toplogy

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Sharing rate: Sharing rate: , ,

where where : Accepted request for : Accepted request for reserving BPreserving BP

: Wavelength used for : Wavelength used for reserving BPreserving BP

Blocking rate:Blocking rate: , ,

where where : Number of call requests: Number of call requests

: Number of accepted call : Number of accepted call requestsrequests

AR

UsedARSharing BP

WBPR

UsedW

R

ARWBlocking C

CCR

RC

AC

ARBP

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Numerical Results and AnalysisNumerical Results and Analysis

Fig.3 Fig.3 Shows model 2,3, and 4 Shows model 2,3, and 4 which adopt load-which adopt load-balancing scheme balancing scheme manifest higher sharing manifest higher sharing rate compared to rate compared to model1 which does not model1 which does not adopt the load-adopt the load-balancing scheme balancing scheme

Shape of graph is Shape of graph is regular at each modelregular at each model

Sharing rate of model 4Sharing rate of model 4• Improved on average Improved on average

30% compared with 30% compared with that of model 1that of model 1

Fig.3 Backup Path Sharing Rate of model 1~4

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Numerical Results and Analysis Numerical Results and Analysis (cont.)(cont.)

Fig.4 (W=32)Fig.4 (W=32)Model 2,3, and 4 have Model 2,3, and 4 have lower blocking rate lower blocking rate than that of model 1than that of model 1

Model 4 has average Model 4 has average 23% lower blocking 23% lower blocking raterate

• Achieve higher Achieve higher network throughputnetwork throughput

Expectation: growing Expectation: growing load balancing effectload balancing effect

• More nodes, links, More nodes, links, and wavelengths per and wavelengths per linklink

Fig.4 Call Request Blocking Rate of model 1~4

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Numerical Results and Analysis Numerical Results and Analysis (cont.)(cont.)

Fig. 5 (W=64)Fig. 5 (W=64)Improved load Improved load balancing effect by balancing effect by doubling the number doubling the number of wavelengths to 64of wavelengths to 64

Model 4 shows 26% Model 4 shows 26% lower blocking rate lower blocking rate on average than that on average than that of model 1of model 1

Fig.5 Call Request Blocking Rate of model 1~4

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Conclusion and Future worksConclusion and Future works

Introduce the concept of load balancing Introduce the concept of load balancing into protection mechanisminto protection mechanism

Achieve 30% higher sharing rate and 23% Achieve 30% higher sharing rate and 23% (w=32), 26% (w=64) lower blocking rate (w=32), 26% (w=64) lower blocking rate compared to the commonly used 1:1 compared to the commonly used 1:1 protection mechanism (model 1) protection mechanism (model 1)

Maintain 100% restoration capabilityMaintain 100% restoration capability

Future WorksFuture WorksApply proposed mechanism to various mesh Apply proposed mechanism to various mesh topologiestopologies

Use the concept of threshold in order to enhance Use the concept of threshold in order to enhance the positive effect of load balancingthe positive effect of load balancing

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ReferencesReferences

[1] Ayan Banerjee et al. “Generalized Multiprotocol Label Switching: An Overview of Signaling Enhancements and Recovery Techniques”, IEEE Communication Magazine, July 2001

[2] Ayan Banerjee et al. “Generalized Multiprotocol Label Switching: An Overview of Routing and Management Enhancements”, IEEE Communication Magazine, Jan. 2001

[3] S. Ramamurthy and Biswanath Mukherjee, “Survivable WDM mesh networks, partⅠ – protection”, INFOCOM ’99, March 1999, Page(s): 744 -751 vol.2

[4] <draft-many-inference-srlg-00.txt>, IETF draft

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Thank Thank you !you !Q & A Q & A

load balancing in protection switching of optical networks hongkyu jeong, gyu-myoung lee information...

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