1 / 13

Brief Announcement: Practical Summation via Gossip

Learn about BubbleStorm, a practical solution for calculating the sum in peer-to-peer networks, and its improvements in terms of round switching, message loss compensation, and bandwidth saving. Discover the challenges and open problems related to the Push-Sum algorithm, including vulnerability to attacks.

twayne
Download Presentation

Brief Announcement: Practical Summation via Gossip

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Brief Announcement:Practical Summation via Gossip Wesley W. Terpstra, Christof Leng, Alejandro P. Buchmann Databases and Distributed Systems Group Technische Universität Darmstadt Germany

  2. Sum calculation in peer-to-peer • Input: every peer has a value • Output: (at least) one peer knows • Useful in computing many global statistics: • Network size • Average utilization • Load balance (standard deviation) • Churn (rate of peer replacement) • Size of stored data For our system, BubbleStorm, we compute  degi(p)

  3. Build on an existing solution • Approaches can be compared by • Message rounds (latency) • Total messages (bandwidth) • Parameters: system size (n), accuracy () • We improve the Push-Sum algorithm for practical use

  4. Analogy: Measuring a lake’s volume

  5. Push-Sum visualized

  6. Stationary Distribution (Steady State) Equilibrium: edges carry the same water and fish in both directions peers have water and fish proportional to degree and clock Perturbations of equilibrium do not affect water/fish ratio

  7. Improvement: Big Fish eat smaller fish

  8. Fish eating in the Network

  9. Stationary Distribution (Steady State)

  10. Other improvements • Round switching • Once the result is accurate “enough”, restart • Provides a running estimate on network statistics • Compensate for message loss • Prevent adding two of the most aggressive fish • Save bandwidth for multiple measurements

  11. Synchrony • Kempe et al. prove correctness with synchronous model, but conjecture that it works asynchronously • We validate this claim by simulation • 1 million peers, 5s gossip interval, find network size:

  12. Open Problem • Push-Sum is very vulnerable to attack • Any peer can completely change the result • This is largely due to the problem statement (sum!) • Simplistic prevention (bounds) easily defeated • Introduce too few of the largest fish type  too large • Switch rounds prematurely  too small & unstable • What is a useful adversary model for summation?

  13. Thanks for listening!

More Related