> From: valdis.kletni...@vt.edu > Date: Mon, 09 May 2011 12:25:55 -0400 > > On Mon, 09 May 2011 18:16:20 +0300, Arie Vayner said: > > Actually, I have just noticed a slightly more disturbing thing on the Yahoo > > IPv6 help page... > > > > I have IPv6 connectivity through a HE tunnel, and I can reach IPv6 services > > (the only issue is that my ISP's DNS is not IPv6 enabled), but I tried to > > run the "Start IPv6 Test" tool at http://help.yahoo.com/l/us/yahoo/ipv6/ and > > it says: > > "We detected an issue with your IPv6 configuration. On World IPv6 Day, you > > will have issues reaching Yahoo!, as well as your other favorite web sites. > > The *really* depressing part is that it says the same thing for me, on a > *known* > working IPv6 network. > > And then when I retry it a few minutes later, with a tcpdump running, it > works. > > And then another try says it failed, though tcpdump shows it seems to work. > > For what it's worth, the attempted download file is: > > % wget http://v6test.yahoo.com/eng/test/eye-test.png > --2011-05-09 11:44:39-- http://v6test.yahoo.com/eng/test/eye-test.png > Resolving v6test.yahoo.com... 2001:4998:f00d:1fe::2000, > 2001:4998:f00d:1fe::2002, 2001:4998:f00d:1fe::2003, ... > Connecting to v6test.yahoo.com|2001:4998:f00d:1fe::2000|:80... connected. > HTTP request sent, awaiting response... 200 OK > Length: unspecified [image/png] > Saving to: `eye-test.png.1' > > [ <=> ] 2,086 --.-K/s in 0s > > > 2011-05-09 11:44:39 (154 MB/s) - `eye-test.png.1' saved [2086] > > Looking at the Javascript that drives the test, it appears the *real* problem > is that they set a 3 second timeout on the download - which basically means > that if you have to retransmit either the DNS query or the TCP SYN, you're > dead as far as the test is concerned.
I have talked to Yahoo engineers about this and they say that their testing has shown that, if it takes more than 3 seconds for a site to load, they start to lose significant traffic. Hence the 3 second timeout. Sadly, I'm afraid that they have a point, but at the same time I suspect that they are assuring failure for almost everyone. A 5 second timeout would probably be more reasonable, but is probably unacceptable to Yahoo management. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: ober...@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751
