In your letter dated Wed, 26 Oct 2016 17:04:18 +0200 (CEST) you wrote:
but instead recommend the OS vendor to install some kind of heuristic to flag for the user somehow that their IPv6 connectivity is degraded, and offer to fault find it... or let's invent some kind of telemetry where these kinds of breakages can be reported to the OS vendor so they can contact the ISP and alert them to the breakage?
I wonder, if a host has a global IPv6 address that is not derived from any kind of transition technology or tunnel, and setting up a TCP connection is either slow or fails, then what percentage is due to an issue close to the host and what percentage close to the target. I.e., if IPv6 is broken is there any reason to believe it is often enough due to ISP provided services that is would be worth reporting it in a roudabout way.
Also, we still have the problem with PMTU blackhole detection and mitigation. Why isn't this turned on more?
I really don't understand this. I guess 'everybody' doing major operating systems still lives in an IPv4-only world with MSS clamping.