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Learn how to hide network failures and maintain reliability in overlay networks. Proactively handle failures and reduce convergence time by employing redundant paths and Anti-Entropy methods. Explore different techniques like Restricted Flooding and multiple disjoint routes for optimizing network resilience. Find solutions to challenges such as loss correlations and scalability limitations. Contact authors Rebecca Braynard and Amin Vahdat for more information.
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Masking Failures Using Anti Entropy and Redundant Independent Paths Rebecca Braynard and Amin Vahdat Internet Systems and Storage Group Duke University http://issg.cs.duke.edu
Building Reliable Overlays • Hide failures in the network from applications using the overlay • Scalable, reliable publish subscribe systems • Goal: • Input: overlay with neighbor connection information and reliability target • Probe neighbors for reliability information • Construct end-to-end paths that match the target level of reliability • Benefit: Proactively handle failures • Avoid convergence time after network failures through redundancy Rebecca Braynard
Restricted Flooding • All nodes in the overlay receive the data • Messages do not travel along every link in the overlay • Prevent nodes from receiving multiple copies • Idea is similar to Anti Entropy: used to maintain consistency between replicas in distributed computing Source Destination Rebecca Braynard
First Step: Maximum Reliability Tree Dest_1 0.951 .94 .98 .96 .95 .92 .96 .99 .98 Source .97 .97 .93 .94 .97 .99 .98 .96 .96 .97 .92 Dest_2 Link Reliability (assume independence) .98 .96 0.922 Highest reliability paths for source to destinations Rebecca Braynard
Second Step: Multiple Disjoint Routes 0.951 Dest_1 .94 0.997 .98 .96 .95 .92 .96 .99 .98 Source .97 .97 .93 .94 .97 .99 .98 .96 .96 .97 .92 0.922 .98 .96 Dest_2 0.996 Basic Flood: 14 Restricted Flooding: 8 Tune connectivity to application specifications Rebecca Braynard
Questions? • Webpage: • http://issg.cs.duke.edu/malachi • E-Mail: • Rebecca Braynard: rebecca@cs.duke.edu • Amin Vahdat: vahdat@cs.duke.edu Rebecca Braynard
Research Problems • Disjoint paths may not be available C A D B • Loss correlations between overlay links Overlay link 2 5 Physical link 1 4 Overlay node 3 6 Internet router • Nodes only have local network state information to make decisions • Only probe direct neighbors in the overlay Rebecca Braynard
Differences: RON • RON: O(N2) probing to obtain network state information • Each node probes every other node in the overlay • Global network state to make routing decisions • Limits scalability Multiple Routes with AE RON Base Overlay Rebecca Braynard
Differences: Mesh-Based Content Routing • MBCR: intermediate nodes receive messages multiple times • Single receiver • We address the problem of finding disjoint routes Restricted Flooding to reduce network resource consumption Intermediate nodes receive the same message multiple times Rebecca Braynard
Link Loss Correlation • Loss rates correlation between links • share a link in the underlying topology .99 .99 .98 .98 .95 .95 Rebecca Braynard