[bcaa7f3a8bbc]

I'd bet it's due to a firmware/software bug triggered by a rare condition, or undefined software behavior trigger by a hardware malfunction. If it's true, it means the root cause would probably never be identified as nobody can reproduce it. It's something pretty scary to think about: We can never guarantee most software would work correctly all the time, empirical testing is often the only practical assessment, and probabilistic bugs such as mysterious crashes cannot be discovered.

But I think the bigger problem is not the packets, but why didn't the backbone reject those malformed packets.