Cloudflare Misconfiguration Causes Recent BGP Route Leak
Cloudflare recently disclosed information about a significant Border Gateway Protocol (BGP) route leak that occurred on January 22. This misconfiguration lasted for approximately 25 minutes, leading to measurable congestion, packet loss, and an estimated 12 Gbps of dropped IPv6 traffic.
BGP Route Leak Explained
The BGP system plays a crucial role in directing data across various autonomous systems (AS) on the internet. A route leak happens when an AS inaccurately advertises routes learned from one peer or provider to another, resulting in unintended congestion or dropped traffic.
Incident Details
- Date of Incident: January 22
- Duration: 25 minutes
- Traffic Impact: Approximately 12 Gbps dropped
In this case, Cloudflare’s announcement indicated that the leak was a mix of Type 3 and Type 4 violations, as defined in RFC7908. The company inadvertently redistributed routes from peers in Miami, affecting external networks beyond its customer base.
Root Cause
The root cause of the BGP route leak stemmed from a policy adjustment aimed at preventing Miami from advertising IPv6 prefixes for Bogotá. This change led to an overly permissive export policy, allowing all internal IPv6 routes to be advertised externally, which attracted unintended traffic flows.
Response and Mitigation
Cloudflare quickly detected the misconfiguration and their engineers manually reverted the changes within the 25-minute time frame. They paused automated processes to halt further impact and subsequently restored the original code. This incident mirrored an earlier occurrence in July 2020.
Future Preventive Measures
To prevent similar incidents, Cloudflare has outlined several strategies:
- Implement stricter community-based export safeguards
- Introduce CI/CD checks for identifying policy errors
- Enhance early detection systems
- Validate RFC 9234 compliance
- Encourage RPKI ASPA adoption
While primarily affecting network reliability, route leaks can also pose security risks, allowing unauthorized parties to intercept and analyze traffic. Cloudflare’s proactive measures aim to enhance both reliability and security for its users.
