Vivaldi Coordinate Service

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Vivaldi Coordinate Service

• Justin Ma, Patrick Verkaik, Michael Vrable
• Department of Computer Science And Engineering
• UCSD
• CSE222A, Winter 2005

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Network Coordinates

• Knowledge of network latencies useful
• All-pairs measurement overly expensive
• Key idea embed nodes into a metric space, where
  distance corresponds to RTT

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Vivaldi Algorithm (cont.)

• Each node updates position incrementally with
  each communication
• Modeled as a spring system
• Movement governed by error estimate of each node

Dabek, et al., SIGCOMM '04
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Vivaldi Evaluation Shortcomings

• Presented evaluation uses static latency
  measurements
• Measurement of response to network changes
  limited
• We need to evaluate this algorithm in a real
  setting

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Outline

• Vivaldi Coordinate Service
• Simulation Results
• VCS Deployment
• Demonstration

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Implementation Goals

• How do we make the landmark and query protocols
  lightweight and accurate?
• Candidate landmark protocol All landmarks ping
  each other
• Candidate query protocol All landmarks ping
  target
• We conduct simulations to investigate other
  candidate protocols

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Simulation Dataset

• PlanetLab all-pair ping
• 11-24 January, 2005
• 15 minute averages
• 166 nodes

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Simulation Landmark Protocol

• Evaluate two communication patterns
• All-pairs
• Every 15 minutes, a landmark pings all other
  landmarks
• Random fraction
• Every 15 minutes, a landmark
• Selects random 10 of other landmarks
• Pings the selected landmarks

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Simulation All-Pair Landmark Protocol

• Highly variable, but after 2.5 days (t240)
• 50 of measurements mostly below 7 error
• 75 of measurements mostly below 20 error

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Simulation All-Pair Landmark Protocol

• 50 node pairs have lt 9 average error
• 80 of node pairs have lt 30 average error

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Simulation All-Pair Landmark Protocol

• Error decreases with time

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Sim Random-10 Landmark Protocol

• After a half day random-10 similar to all-pair

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Simulation Query Protocol

• The DOS approach

3 least-error
Uses landmarks with lowest Vivaldi error
Uses all landmarks
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Simulation Query Protocol

• Not bad
• Few probes needed
• Few probers needed

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Simulation Query Protocol

• Can do better
• Two least-error nodes were close together
• gt Pick better probers

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Live Deployment

• PlanetLab (roughly 15 nodes are landmarks)
• Landmarks implemented in Python
• Landmark software deployed using PLuSH

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Live Deployment Landmark Protocol

• Current deployment uses
• Changing set of 6 nodes (40 of total)
• Half nearby nodes
• Half random (distant)

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Live Deployment Query Protocol

• Current deployment uses
• 3 least-error nodes

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Future Work

• Investigate adaptive landmark protocols
• More optimal query protocol
• Improve Vivaldi Coordinate Service Implementation
• Robustness
• Security
• Caching
• Peer management
• Evaluate filtering of raw ping data

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Conclusion

• Simulations show the potential of Vivaldi and a
  lightweight coordinate service
• Constructed Vivaldi Coordinate Service using
  guidance from simulations

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Demonstration

• 3 Interfaces
• Text-based UDP query interface (netcat)
• PlanetLab Sensor http//ironic.ucsd.edu/
• Animation Webpage http//ironic.ucsd.edu/vivaldi/