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Self-Healing Optical Access Networks

Presented by Jithin P

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Agenda

• Optical Access Network• Issue• Existing Solution• Proposed Solution• Advantages of proposed solution over

existing solution• Compatibility with existing architecture

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Optical Access Network

Point to PointActive Optical NetworkPassive Optical Network

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Optical Access Network

• Connects subscribers to their service providers

OLT

ONU

ONU

ONU

Back bone

OLT : Optical Line TerminalONU : Optical Network Unit

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Issues

•ONU Failure•Link Failure•OLT Failure

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Existing Solution• Dual-home Architecture

OLT#1

OLT#2

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Issues of Dual-home Architecture

• Cost• Fault monitoring methods • Disruption Duration

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Requirements for low cost reliable service

• Survivability must be robust• Failure can be monitored in service• Service can be recovered with minimum

disruption duration• CapEx and OpEx should be minimized

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So What We Need ?

• An access network that can detect and recover from failure itself, with in a matter of second, with low operational & implementation cost.

• And it must be compatible with existing infrastructure.

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SHOAN :- Basic Architecture OLT#1

ONU#11

ONU#12

ONU#13

ONU#14

ONU#22

ONU#23

ONU#21 ONU#24

OLT#2

OLT#1

OLT#2

ONU#11

ONU#12

ONU#13

ONU#14ONU#22

ONU#23

ONU#24

ONU#21

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How to make it possible ?Using cross bar switch

OLT#2

ONU#11

ONU#12 ONU#13

ONU#14

ONU#22

ONU#23

ONU#24

ONU#21

OLT#1

OLT#1

OLT#1

Crossbar#1

Crossbar#2

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For tree network

ON

U#22

OLT#2

ON

U#21

ON

U#12

OLT#1

ON

U#11

OLT#1

How to make it possible ?

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Advantages over Dual-Home

• Cost Issue: • Cost(OLT)>>>Cost(Crossbar switch)

• Fault Monitoring• Faults can be self-discovered and self-managed by only

monitoring bar connections of cross bar switches

OLT#2

ONU#11

ONU#12 ONU#13

ONU#14

ONU#22

ONU#23

ONU#24

ONU#21

OLT#1

OLT#1

OLT#1

Crossbar#1

Crossbar#2

Failure Monitoring

Failure Monitoring

Failure Occur

Failure Occur

Fault Localization

Triggering network protection

Failure Repair

Service resumed

Finished protection function

Network recovery

Service self-recovery

Failure Repair

Network recovery

Fault Localization

NO

YES

NO

YES

Existing SolutionSelf-Healing System

Disruption Duration Service can be self recovered by just turning the affected cross bar from bar state to cross state, without the process of fault localization and identification.

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Compatibility With Existing Architecture (PON)

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Message flow in SHOAN

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Conclusion

• SHOAN is– Robust because risks are disjointed– Reliable because disruption duration is minimized– Low cost solution because back up components

are not necessary any more.• Further research

• Crossbar failure• What will happen if both OLT fails?• How CFO and CEO communicate ?• Degradation of service

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Questions ?