Broken packets: IP fragmentation is flawed

What this post added

This post delves into the technical challenges of IP fragmentation and the importance of Path MTU Discovery for reliable internet communication. It highlights how Cloudflare's network infrastructure must contend with issues arising from intermediate network devices (routers, NATs, middle boxes) that can interfere with fragmentation and ICMP 'Packet too big' messages, impacting protocols like TCP. The post details various scenarios where these issues manifest and the complexities introduced by modern network architectures like ECMP and Anycast, underscoring the need for robust network engineering to ensure consistent performance and connectivity.