contact with One & One ?

Fri Oct 14 14:02:38 CEST 2016

The issue here is that customers (the ones that browse the broken web sites), don’t know about MTU, ICMP, etc.

So I guess is in your side as the “provider” of the content, who is the interested party in making sure it works for “all” your possible customers.

Up to now, every time I’ve seen this problem was just related to ICMPv6 being filtered, as many folks do in IPv4 …

By the way, interesting article, I didn’t read it before:


-----Mensaje original-----
De: < at> en nombre de Paul Stewart <paul at>
Responder a: <paul at>
Fecha: viernes, 14 de octubre de 2016, 13:52
Para: Mikael Abrahamsson <swmike at>
CC: <ipv6-ops at>, JORDI PALET MARTINEZ <jordi.palet at>
Asunto: Re: contact with One & One ?

    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 … 
    > On Oct 14, 2016, at 7:45 AM, Mikael Abrahamsson <swmike at> 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: swmike at

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