Verifying Maximum Link Loads in a Changing World

Learn about Velo, the first verification system that efficiently finds maximum link loads under network failures and route changes in this 17-minute conference talk from NSDI '25. Discover how researchers from ETH Zürich and University College London address the critical challenge of analyzing worst-case link loads in network operations, which traditionally only considered failure scenarios while ignoring BGP route changes. Explore Velo's innovative approach that massively reduces the enormous space of possible route changes through three key techniques: a router-based abstraction for route changes, theoretical characterization of scenarios leading to worst-case link loads, and approximation of input traffic matrices. Understand how this system can accurately compute all worst-case link loads in large ISP networks within minutes, providing network operators with essential tools to strengthen network configurations, enhance network management, and make informed business decisions in an increasingly demanding networking environment.