Survivor: an Enhanced Controller Placement Strategy for Improving - - PowerPoint PPT Presentation
Survivor: an Enhanced Controller Placement Strategy for Improving - - PowerPoint PPT Presentation
Survivor: an Enhanced Controller Placement Strategy for Improving SDN Survivability Lucas F. Mller , Rodrigo R. Oliveira, Marcelo C. Luizelli, Luciano P. Gaspary, Marinho P. Barcellos Federal University of Rio Grande do Sul (UFRGS), Brazil
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Software-Defined Networking Design
- Changing the way networks are designed and managed
- Separates the control plane from the data plane
- Moves the control logic to an external entity (Controller)
- Controller provides resources and abstractions to facilitate
programming … Despite its benefits, SDN created an inherent dependency relationship between forwarding devices and the controller.
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Software-Defined Networking Design
Forwarding devices Set of SDN Controllers Controller Placement Problem
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Software-Defined Networking Design
Controller Placement Problem
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Software-Defined Networking Design
Controller Placement Problem
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Software-Defined Networking Design
Controller Placement Problem
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Software-Defined Networking Design
Controller Placement Problem
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Software-Defined Networking Design
Controller Placement Problem
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Software-Defined Networking Design
Controller Placement Problem
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Software-Defined Networking Design
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Controller Placement Problem
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Software-Defined Networking Design
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Controller Placement Problem
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Software-Defined Networking Design
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Controller Placement Problem
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Software-Defined Networking Design
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Ok, the control plane design is ready. Controller Placement Problem
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“The network is down.”
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Software-Defined Networking Design
1 1 1 1 2 2 2 2 3 4 4 3 4 3 4 4 3 4 4 4 4
X
1 1 1 1 2 2 2 2 3 4 4 3 ? 3 ? ? ? ? ? ? ?
X X
1 1 1 1 2 2 2 2 3 4 4 3 4 3 4 4 3 4 4 4 4
# 5 # 4 # 4 # 4 # 9
Single link failures Multiple connectivity failures Controller overload
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Controller Placement Strategy for Improving SDN Survivability
Goal: novel controller placement strategy that deals with control plane survivability in large scale SDN networks. Provide and maintain network services in face of
- perational challenges
React and attempt to recover from harmful events
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Outline
- Introduction: context and motivation
- Proposed Approach: strategy and modeling
- Results: resilience and overload
- Conclusion
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Proposed Approach
Goals
– Connectivity
Increase path diversity between device-controller
– Capacity
Avoid controller overload
– Recovery
Define a methodology for composing smarter failover mechanisms
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Proposed Approach: Overview
Divided in two complementary parts
– Defines the placement of controllers instances – Compose the list of backup controllers for each device in the network
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Proposed Approach: two complementary parts
– Defines placement for controller instances
32 33 34 1 6 24 25 7 4 5 8 9 28 18 15 16 17 14 12 20 13 11 21 26 22 27 23 29 10 19 3 30 39 38 37 36 2 35 31 3 3 2 5 3 2 2 2 2 4 4 4 4 5 5 4 1 4 1 1 1 1 1 1 4 2 5 5 5 2 5 3 3
Network topology Controller placement
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Proposed Approach: two complementary parts
– Specifies backup controllers for each device in the network
3 3 2 5 3 2 2 2 2 4 4 4 4 5 5 4 1 4 1 1 1 1 1 1 4 2 5 5 5 2 5 3 3
2 4 5 1 4 2 1 3 4 1 2 5
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Proposed Approach: modeling
Optimal Linear Model for Controller Placement
– Strategy modeled as optimization problem – Achieve the optimal solution – Survivor strategy: Integer Linear Program, 1 objective (maximize connectivity between device-controller)
Heuristics for Defining Lists of Backup Controllers
– Compose the lists of backup controllers – Eliminating the need to manually determine the list – Proximity and Residual capacity-based heuristics – Proposed generic framework for designing heuristics
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Outline
- Introduction: context and motivation
- Proposed Approach: strategy and modeling
- Results: resilience and overload
- Conclusion
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Methodology
Configuration
– Three different WAN topologies: Internet2 (10 nodes, 15 links), RNP (27 nodes, 33 links) and GÉANT (40 nodes, 61 links) – Controllers capacity: 1800 kilorequests/s – Forwarding devices requests: 200 kilorequests/s – Percentage of controller backup resources: 30%
Comparison method
– Resilient placement strategy Zhang et al., denoted by MCC
[CUNHA et al., 2009; KNIGHT et al., 2011; TOOTOONCHIAN et al., 2012; ZHANG et al., 2011]
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Methodology
Four metrics
– Resilience
- Resilience equation used by Zhang et al., 2011
- Cardinal of edge-connectivity
– Overload
- Number of overloaded controllers
- Load distribution for each of the controller instances
[CUNHA et al., 2009; KNIGHT et al., 2011; TOOTOONCHIAN et al., 2012; ZHANG et al., 2011]
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Results: resilience
Probability of connectivity loss
(Resilience equation, Zhang et. al)
Survivor reduces the probability of connectivity loss.
0.1 0.2 0.3 0.4 0.5 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1
Probability of connectivity loss Failure Probability
SVVR GEANT MCC RNP INTERNET2 0.2 0.4 0.6 0.8 1 0.2 0.4 0.6 0.8 1
Probability of connectivity loss Failure Probability
SVVR GEANT MCC RNP INTERNET2
(a) 1% a 10% (b) 0% a 100%
gain gain
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Results: resilience
Effect of exploring path diversity
(Cardinal of edge-connectivity)
Path diversity increases the network survivability, and it requires explicit consideration to be fully explored.
0.2 0.4 0.6 0.8 1 5 10 15 20
% of failure scenarios # of Disconnected elements
SVVR MCC
1 3 6
0.2 0.4 0.6 0.8 1 2 4 6 8 10
% of failure scenarios # of Disconnected elements
SVVR MCC+
1 3 6
CDFs of disconnected devices for all possible cases of 1, 3 and 6 link disruptions
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Results: overload
Number of overload scenarios
Network convergence after disruptions is highly sensible to predefined information in failover mechanisms.
5 10 15 20 SVVR MCC SVVR MCC SVVR MCC
# of overload scenarios
Normal Operation Failover strategy: Proximity Failover strategy: Residual Capacity
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Results: overload
Network state after convergence
(Load distribution)
Controller overload can be handled proactively by adding capacity-awareness and setting backup resources.
50 100 150 200 250 300 C1 C2 C3 C4 C5 C6 C7 C1 C2 C3 C4 C5 C6 C7
Load (%) SVVR MCC
50 100 150 200 250 300 C1 C2 C3 C4 C5 C6 C7 C1 C2 C3 C4 C5 C6 C7
Load (%) SVVR MCC
(b) Residual Capacity heuristic (a) Proximity heuristic
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Outline
- Introduction: context and motivation
- Proposed Approach: strategy and modeling
- Results: resilience and overload
- Conclusion
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Final Remarks
Contributions
– Significant reduction on connectivity loss – More realistic controller placement strategy – Smarter recovery mechanisms – Optimization model in order to generate optimal results
Ongoing work
– Studying meta-heuristics – Extend evaluation
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