BGP zombies and excessive path hunting

This post details the formation and impact of BGP zombies and excessive path hunting, explaining how route withdrawals can lead to temporary routing loops and reachability issues. It describes the underlying causes, including router software bugs, processing slowness, and the Minimum Route Advertisement Interval (MRAI). The post also illustrates how Cloudflare's BYOIP on-demand advertisement feature can increase the frequency of these events and presents observed instances of BGP zombies within upstream partners and Cloudflare's own network. It highlights the longer convergence times observed for IPv4 compared to IPv6.