<div dir="ltr">1452 is the good one :D<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Jan 21, 2014 at 9:30 PM, Ez Egy <span dir="ltr"><<a href="mailto:ezegyemailcim123@gmail.com" target="_blank">ezegyemailcim123@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">The solution was setting the MTU to 1480 in radvd in the router: <br><br>option AdvLinkMTU 1480<br>
# option AdvLinkMTU 1452<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Jan 20, 2014 at 5:22 PM, Ez Egy <span dir="ltr"><<a href="mailto:ezegyemailcim123@gmail.com" target="_blank">ezegyemailcim123@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div>As I said: <br><br>1) "I have a native IPv6 connection on my Desktop behind my router." -> So there is no tunnel. Only native IPv6 that the Hungarian <a href="http://telekom.hu" target="_blank">telekom.hu</a> gives. <br>
</div>2) We will try out setting manually the MSS to 1392, hopefully that could be a good workaround. <br>3) We will try out the site: <a href="http://netalyzr.icsi.berkeley.edu/" target="_blank">http://netalyzr.icsi.berkeley.edu/</a><br>
<br></div><div>I will post the status here later, Thanks!<br></div></div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Jan 20, 2014 at 11:59 AM, Tore Anderson <span dir="ltr"><<a href="mailto:tore@fud.no" target="_blank">tore@fud.no</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">* Ez mail<br>
<br>
> Since I have no fr**king clue what could the problem be, I'm trying on<br>
> this list :)<br>
<br>
I concur 100% with Erik's assessment that this in all likelihood is a<br>
PMTUD problem, specifically in the web_server->your_desktop direction.<br>
<br>
I'd just like to add that the fact that you see it happening to several<br>
independent websites that are known to be operated by competent staff,<br>
and that the problem comes and goes, further indicates that it is due to<br>
rate-limiting of ICMPv6 PTB replies from your tunnel broker's tunneling<br>
router/server.<br>
<br>
The ICSI Netalyzr (<a href="http://netalyzr.icsi.berkeley.edu/" target="_blank">http://netalyzr.icsi.berkeley.edu/</a>) will give you<br>
very useful debugging output from the outside point of view. You might<br>
have to run it a few times to to reveal the MTU blackhole though, due to<br>
the problem's intermittent nature.<br>
<br>
As Erik mentions, lowering the TCP MSS will likely work around the<br>
problem. You can probably do this by having the RAs your router emits to<br>
the LAN advertise an MTU of 1452 to match your tunnel (which in turn<br>
should make your desktop default to a TCP MSS of 1392), and/or have your<br>
router rewrite ("clamp") the MSS value in TCP packets it forwards<br>
to/from the tunnel to 1392.<br>
<br>
Or, even better, get rid of the tunneling crap and get native IPv6. This<br>
is a very common problem for IPv6 tunnels. As a web site operator I<br>
would actually prefer it if people stayed IPv4-only until their ISP<br>
could provide them with properly supported IPv6 connectivity. Oh well...<br>
<span><font color="#888888"><br>
Tore<br>
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