On 11/30/19 8:55 PM, Valdis Klētnieks wrote:
User apps prefer IPv6, Netflix stops, users complain And fallback to IPv4 fails to happen, why, exactly?
Inability to signal application-level failure on IPv6 and that fallback to IPv4 would succeed. Netflix definitely exhibits this. I've also noticed that a lot of Cloudflare-hosted apps/sites block AS6939 outright which mostly only affects IPv6 as they don't actually originate much end-user-facing IPv4 space. The result is an HTTP/403 which most browsers do not interpret as a response that could be remedied by "happy eyeballs" type behavior. Whether banning an entire ASN like that in precisely a situation where this kind of thing is likely to occur is a good practice or not is left as an exercise to the reader. -- Brandon Martin