Iran Experienced Brief BGP Disruption on July 21

Iran experienced a brief but notable disruption to its Border Gateway Protocol (BGP) routing on July 21, 2026. The event lasted approximately 35 minutes, centered around 20:55 UTC. The disruption was isolated to the network control plane, with data plane connectivity remaining largely unaffected.

Technical Details

The BGP signal, which measures the visibility of Iranian IP prefixes in the global routing table, recorded a severity score of 35 during the event. The median number of visible prefixes dropped by approximately 1% from its peak. Concurrently, other measurement signals showed minor deviations: active probing for IPv4 reachability saw a 6% drop, while backscatter-based traffic measurements indicated a more significant 32% decline from peak levels. The cause has not been publicly attributed.

The disruption was resolved by 21:30 UTC.