I can confirm this bug with the 3.13 kernel shipped with Ubuntu 14.04. The 3.2 kernel shipped with Ubuntu 12.04 did not have the problem, all download were succeeding. The problem started after upgrade to 14.04. The problem also solved after downgrading the kernel to 3.2 by downloading the latest 12.04 (Linux 3.2) one from the PPA.
Disabling TCP SACK also resolved the issue. I also tried newer PPA kernels, at least the next one for release with next Ubuntu Update (3.14) does not solve the problem yet. In our case the problems happens mostly with far-away or slower DSL connections, trying to download large files from our webserver. The download starts fine, but suddenly slows down to 0 bytes/sec. It then sometimes recovers, but fails again after a short while. The tcpdump showed, that the client is sending SACKs over and over, but the Ubuntu kernel does not understand them. In our case we also have Cisco hardware inbetween. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1388786 Title: TCP stale transfer with erroneous SACK information To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1388786/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
