Tell us about an interesting network incident from practice.

One of the interesting network incidents I encountered was related to an unexpected drop in performance due to incorrect traffic routing. In our infrastructure, several data centers were connected via VPN, and due to a configuration error in BGP, routes started to 'loop' — packets were cycling between nodes, causing delays and packet loss.

For diagnostics, we used traceroute and router log analysis. It turned out that, due to a configuration update, one of the routers announced incorrect routes, leading to loops.

The solution involved adjusting BGP filters and adding route monitoring to quickly detect similar anomalies in the future. This incident highlighted the importance of thorough network policy checks and routing configuration, as well as the need for automated network monitoring.