[outages] fonts.gstatic.com IPv6 issues...

[Mark Kamichoff]

On Sat, Nov 08, 2014 at 08:07:56AM -0500, Stephen Frost via Outages wrote:
> I've been having issues w/ google IPv6 (more-or-less all services
> operating over 80/443 have been really bad, though imap/993 has had
> issues also) for at least 18 hours from a SixXS tunnel which terminates
> in Ashburn.

"me too" (I'm in Seattle, USA)

I've narrowed down this issue to Google ignoring ICMPv6 PTBs.  It
sometimes works sporadically for me, though.  Here's an example w/some
tcpdumps:

http://www.prolixium.com/share/txt/google-ipv6-pmtud-fail.txt

Relevant lines are the following:

13:51:34.046171 IP6 2001:48c8:1:2::2 > 2607:f8b0:4005:802::1006: ICMP6,
packet too big, mtu 1280, length 1240
13:51:34.562579 IP6 2607:f8b0:4005:802::1006.443 >
2001:48c8:1:105:21c:c0ff:feb2:8dbd.33936: Flags [.], seq 1:1429, ack
279, win 232, options [nop,nop,TS val 3392471676 ecr 756572814], length
1428

Google never lowers the packet length and so the connection times out.
As others have mentioned, this only really affects tunneled users.

I've seen other organizations break this over the years but I never
thought Google would make the list.. 

- Mark

-- 
Mark Kamichoff
prox at prolixium.com
http://www.prolixium.com/
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