Messages in this thread | | | Subject | Re: tcp timestamp issues with google servers | From | Eric Dumazet <> | Date | Thu, 17 May 2012 20:12:43 +0200 |
| |
On Thu, 2012-05-17 at 11:39 +0200, Miklos Szeredi wrote: > Sometimes connection to google.com, gmail.com and other google servers > doesn't work or takes ages to connect. When this hits it hits all > google servers at the same time and it's persistent. It never happens > to anything other than google. Rebooting helps. Rarely it goes away > spontaneously. > > Apparently google is sometimes replying with an invalid TSecr timestamp > value (smaller than the one sent in the last packet) and this confuses > the Linux TCP stack which either discards the packet or sends a Reset. > > Network dump attached. > > I found only a couple of references to this issue: > > http://gotchas.livejournal.com/3028.html > > http://groups.google.com/group/comp.os.linux.networking/browse_thread/thread/29f56feded11b42a > > Turning tcp timestamps fixes the issue: > > sysctl -w net.ipv4.tcp_timestamps=0 > > Not sure why this happens only to me and a very few others. > > It appears to be an issue with google TCP stack (is it a modified > stack?) but I thought about issues in my network switch (restarting it > doesn't help) or something in the ISP, but those look unlikely. > > Any ideas? > > Thanks, > Miklos > > > > 1 0.000000 192.168.28.100 -> 74.125.232.226 TCP 51303 > http [SYN] Seq=0 Win=14600 Len=0 MSS=1460 SACK_PERM=1 TSV=35355050 TSER=0 WS=5 > 2 0.002730 74.125.232.226 -> 192.168.28.100 TCP http > 51303 [SYN, ACK] Seq=0 Ack=1 Win=14180 Len=0 MSS=1430 SACK_PERM=1 TSV=1184565067 TSER=35325344 WS=6
Do you really have 2730 usec RTT between you and this (Google ?) server ?
Are you sure this is not a broken middle box ?
| |