ECN

Wed Nov 13 16:50:28 UTC 2019

On 13 November 2019 17:20:18 CET, Matt Corallo <netadmin at as397444.net> wrote:
>This sounds like a bug on Cloudflare’s end (cause trying to do anycast
>TCP is... out of spec to say the least), not a bug in ECN/ECMP.

Even without anycast, an ECMP shouldn't hash on the ECN bits. Doing so will split the flow over multiple paths; avoiding that is the whole point of doing the flow-based hashing in the first place.

Anycast "only" turns a potential degradation of TCP performance into a hard failure... :)

-Toke