Re: ECN

On 13 November 2019 17:20:18 CET, Matt Corallo <netadmin@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