I tested from my home and happy eyeballs is not falling back to IPv4. So, I tend to suspect that is not ICMPv6 filtering, but something else, such as wrong load balancer or ECMP configuration. Regards, Jordi -----Mensaje original----- De: NANOG <nanog-bounces@nanog.org> en nombre de Carl Byington <carl@five-ten-sg.com> Responder a: <carl@five-ten-sg.com> Fecha: sábado, 19 de noviembre de 2016, 3:22 Para: <nanog@nanog.org> Asunto: Re: pay.gov and IPv6 > > I am working with pay.gov.clev@clev.frb.org, trying to explain the > problem. The intersection of government bureaucracy and technical issues is frustrating to say the least. I just sent the message below, but have no expectation that it will change anything. ============== On Fri, 2016-11-18 at 12:39 +0000, CLEV Pay Gov wrote: > It would be best to discuss this via phone. Please contact our help > desk at the number below and we could see if there's anything we could > do over the phone to help troubleshoot. That is hopeless. Verbal technical discussions rarely work unless both sides can see the same text. Have you ever tried (while talking on the phone) to get someone to type in clev.frb.org without making a bunch of mistakes in the spelling?? Anyway, just for my amusement, I did call 800-624-1373, Option #2, and am on the line now, trying to explain this. 10 minutes and counting. Ok, there does not seem to be any overall ticket for "pay.gov does not work at all". They refuse to open a tech support ticket. > If not, we may need to open a ticket for our technical support. Please open a ticket, and attach the following text for your tech support folks. Alternatively, have them look at the "pay.gov and ipv6" thread on nanog: http://mailman.nanog.org/pipermail/nanog/2016-November/thread.html www.pay.gov has an IPv6 address of 2605:3100:fffd:100::15, but that machine or its upstream routers are filtering icmpv6 messages. That web site is not accessible from systems with an MTU of 1280 bytes. The test case is: echo -e 'GET /public/home HTTP/1.0\n' | \ openssl s_client -servername www.pay.gov -ign_eof -connect \ '[2605:3100:fffd:100::15]:443' Run that (or just use a browser to try https://www.pay.gov) from a system with a 1500 byte MTU, and it works. Run it from a system with upstream connectivity via a tunnel, so the path MTU is smaller, and it fails. Such tunnels are common for IPv6. Please stop filtering icmpv6. ********************************************** IPv4 is over Are you ready for the new Internet ? http://www.consulintel.es The IPv6 Company This electronic message contains information which may be privileged or confidential. The information is intended to be for the use of the individual(s) named above. If you are not the intended recipient be aware that any disclosure, copying, distribution or use of the contents of this information, including attached files, is prohibited.