Messages in this thread | | | Date | Fri, 12 Feb 1999 16:03:44 +0100 | From | Andi Kleen <> | Subject | Re: Weird tcp performance differences with 2.0 and 2.2 kernels |
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On Fri, Feb 12, 1999 at 06:15:27AM +0100, David C Niemi wrote: > > Users are reporting odd and unpleasant FTP hangs on ftp.tux.org as well, > which is now running 2.2.1 with the latest fixed wu-ftpd. These problems > did not occur with the 2.0.36 kernel but did with 2.2pre6; I'm not quite > sure whether they occured in the 2.1.126-8 era because the UP flu made > things unusable back then. > > The hangs do not ALWAYS happen, they are more likely on more remote > connections and on connections via firewalls (in the latter case the > connections work fine for a similar FTP server running 2.0.36 and used to > work fine for ftp.tux.org prior to 2.2.x.
Most likely those firewalls can't handle extended TCP options or they are connected via a router with broken VJ header compression. Try turning them off with:
for i in tcp_timestamps tcp_sack tcp_window_scaling ; do echo 0 >/proc/sys/net/ipv4/$i done
Those host will have problem with most new TCP stacks though.
Another possible explanation would be if they block all of ICMP, there is a MTU <your interface MTU somewhere on the path and you compiled your 2.0.36 without path mtu discovery. In this case you could turn it off via /proc/sys/net/ipv4/ip_no_pmtu_disc, but I would recommend against it. Not using path mtu discovery adds a significant cost to the network.
-Andi
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