At $$$job we run quite a bit of dual stack towards customers as an ISP (mainly PPPoE) - our own public website fails the PTB test and quite honestly we’ve never fixed it. it works for lots of customer/visitors but breaks for others (and they fail back to IPv4) - we thought it was only external tunnel visitors but have found out otherwise… never fully understood what was going on and I keep meaning to look at it ..
NGINX front ends load balanced via anycast … pretty standard Ubuntu 16.04LTS setup on the server side. From what I’ve read it seems to be an ECMP related problem like what CloudFlare published a blog about … Paul > On Oct 14, 2016, at 7:45 AM, Mikael Abrahamsson <swm...@swm.pp.se> wrote: > > On Fri, 14 Oct 2016, JORDI PALET MARTINEZ wrote: > >> I think is time to retire happy-eye-balls, it is the only way the people >> will react to those issues! > > Happy eyeballs doesn't solve PMTU blackhole. > > So this is actually customer breakage occuring, but I imagine lots of ISPs > are actually doing MSS re-write and/or announcing lower than 1500 MTU on the > customer LAN, so even if a customer has PPPoE with 1492 MTU, they still won't > see this problem. > > I have seen swedish authorities websites with same "won't-respond-to-PTB", no > answer there either to fault reports. > > -- > Mikael Abrahamsson email: swm...@swm.pp.se
