hello, I confess using IPv6 behind a 6in4 tunnel because the "Business-Class" service of the concerned operator doesn't handle IPv6 yet. as such, I realised that, as far as I can figure, ICMPv6 packet "too-big" (rfc 4443) seem to be ignored or filtered at ~60% of ClouFlare's http farms as a result, random sites such as http://nanog.org/ or https://www.ansible.com/ are badly reachable whenever small mtu are involved ... support@cloudflare answered me that because I'm not the owner of concerned site, and because of security reasons, they wouldn't investigate further. are there security concerns with ICMP-too-big ? regards, -- Jean-Daniel Pauget http://rezopole.net/ Rezopole/LyonIX +33 (0)4 27 46 00 50