strategies for enhanced dual failure restorability with static or reconfigurable p -cycle networks
DESCRIPTION
Strategies for Enhanced Dual Failure Restorability with Static or Reconfigurable p -Cycle Networks. International Conference on Communications (ICC) Paris, France - June 22, 2004 Dominic A. Schupke* Siemens AG, Corporate Technology Otto-Hahn-Ring 6, 81730 Munich, Germany E-mail: - PowerPoint PPT PresentationTRANSCRIPT
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International Conference on Communications (ICC)Paris, France - June 22, 2004
Dominic A. Schupke*Siemens AG, Corporate TechnologyOtto-Hahn-Ring 6, 81730 Munich, GermanyE-mail:
Wayne D. Grover, Matthieu ClouqueurTRLabs and University of Alberta7th Floor, 9107 116 St NW, Edmonton, Alberta, Canada T6G 2V4E-mail: {grover,clouqueur}@trlabs.ca
*Results from work at Technische Universität München and TRLabs
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© TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22
Outline
• Introduction
• The p-Cycle Concept
• p-Cycles and Dual Failures
• Network Design
• Results
• Conclusions
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© TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22
Introduction
Preconfigured protection cycles (“p-cycles”):
• Applicable in many kinds of networks
• High capacity-efficiency
• Fast protection switching times
• For span-protection:100% restorability against any single span failure
Our focus:
• Provide enhanced or optimized levelof dual-failure restorability
• Static and reconfigurable p-cycles
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The p-Cycle Concept
A p-cycle in a mesh network:
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The p-Cycle Concept
On-cycle link failure:
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The p-Cycle Concept
Straddling link failure:
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Straddling link
Path 1
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The p-Cycle Concept
Straddling link failure:
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Path 2
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Assumptions on Dual Failures
• Dual failure scenarios:
• Assumption: t1 + t1,rec. < t2
• p-Cycles: trec. ~ 50 ms
t1 t1+t1,rec. t2
First (span)failure
Recovery fromfirst failure
Second failure
t2+t2,rec. t2+t2,rep.t1+t1,rep.
Recoveryfrom second failure (if possible)
Repair offirst failure
Repair ofsecond failure
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Static p-Cycles and Dual Failures
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Static p-Cycles and Dual Failures
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No recovery for B-C from second failure
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Static p-Cycles and Dual Failures
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Static p-Cycles and Dual Failures
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Recovery from second failure
t1
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p-Cycle B
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Susceptibility Concept
• p-Cycle susceptible to a dual failure combination:Both failures affect working spans protected by it
• p-Cycle protects s working spans Susceptible to s (s-1) failure events
• Susceptibility s per p-cycle not larger than given σmax
• Restrict when selecting eligible p-cycles for design
Other approach:
• Failure dispersal concept (see paper)
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Reconfigurable p-Cycles and Dual Failures
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Reconfigurable p-Cycles and Dual Failures
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Reconfigurable p-Cycles and Dual Failures
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Reconfigurable p-Cycles and Dual Failures
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Reconfigurable p-Cycles and Dual Failures
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Recovery from second failure
t1
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p-Cycle formed- after t1 and
- before t2
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Network Design
Cost-optimal design:
• Length-weighted utilization of network
Single-failure restorability:
• 100% restorability guaranteed
Dual-failure restorability:
• R(i,j): Restorable fraction of affected working capacity after dual failure of spans i and j
• R2: Average over all dual failure cases
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Network Design
p-Cycle design
Static p-cycles
No R2 optimization R2 optimization
Protect vulnerableworking capacity only
Protect anyvulnerable capacity
Protect vulnerableprotection capacity only
After first failure
Reconfigurable p-cycles
No R2 optimization R2 optimization
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© TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22
COST239 Case Study Network
• Hypothetical pan-Europeanoptical network ofCOST239 project
• Traffic matrix modifiedto lightpath entries
• Average nodal degree: dav = 4.7
• Three-connected(connected after anydual span failure)
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Results for Static p-Cycles
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Reconfiguration
σmax=4
σmax=13
σmax=9
smaller σmax
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Results for Reconfigurable p-Cycles
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Vulnerable workingcapacity protected only
Fraction of p-cycleschangeable in form
Only additional p-cycles
100% 5% 0%
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© TRLabs / University of Alberta and Siemens AG, CT IC 2 ON, Dominic Schupke, 2004-06-22
Conclusions
Capacity design methods:
• Static p-cycles:• Improved dual-failure restorability
• Susceptibility viable approach to control restorability
• Reconfigurable p-cycles: • Complete dual-failure restorability
• Different operational options
Outlook:
• Reconfigurable p-cycles in networks designed for single-failure restorability only
• Multiple protection classes