Devsolved
Symptom
Users globally reported that Google Search, YouTube, and Google Cloud were unreachable. Network engineers tracing the traffic noticed that packets destined for Google were being routed to China Telecom, then to a small ISP in Nigeria (MainOne), where they were dropped.
What is BGP?
The Border Gateway Protocol (BGP) is the postal service of the internet. Networks "advertise" which IP addresses they own. If Network A says "I know the shortest path to Google," other networks will send their Google traffic to Network A.
- MainOne (the Nigerian ISP) accidentally updated their BGP tables to claim they were the best path to 212 of Google's IP prefixes.
- China Telecom, MainOne's upstream provider, lacked BGP route filtering. They blindly accepted MainOne's claim and forwarded it to the rest of the internet.
Networking Cables
Root Cause
BGP relies on a trust-based system. Because China Telecom is a massive Tier-1 provider, when they told the world "Send your Google traffic through us (to Nigeria)", ISPs like Comcast and AT&T updated their routing tables immediately.
Code
bash
// BGP Advertisement (Simplified)
Prefix: 8.8.8.0/24
AS_PATH: 4809 (China Telecom) -> 37282 (MainOne)
// Result: Traffic enters MainOne and dies (blackholed).Resolution
Within 74 minutes, Google and Cloudflare worked with upstream transit providers to sever the rogue BGP announcements. The incident highlighted the desperate need for RPKI (Resource Public Key Infrastructure) to cryptographically verify BGP route announcements across the internet.
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