----- Original Message ----- From: Alistair Tonner <Alistair@xxxxxxxxxx> Date: Sunday, May 1, 2005 5:10 am Subject: Re: Linux forwarding Win XP hosts VERY slowly > On April 30, 2005 01:41 pm, Dave Cinege wrote: > > I've built an advanced rotuign appliance, and I'm having 2 > outstanding> problems, that I'm being to think are related to the > linux ip/netfilter > > stack, choking on XP traffic (possiblity XP-SP2) hosts that are > on the LAN. > > I'm running 2.4.30 at the moment. > > > > The 2 problems I'm seeing: > > > > 1) Forwarded traffic (most notably web) is VERY slow with XP > clients.> > > Example: Saw this last 2 nights ago: Appliance has a linksys > Wifi bridge > > attached to a NIC. Customer browses through the appliance to the > Linksys> config page. It moves like molasses. He browse to the > local Zope hosted > > made page. Slow as hell. I unplug his machine, and plug my linux > laptop> into same switch port. Linksys and Zope pages load adn > reload instantly. > > Plug his machine in....slow again. > > > > 2) Zope serves user interface pages for the appliance. Zope has been > > locking solid for no apparent reason, but only when and Windows > host is > > attached. The trick is SOME windows machine don't seem to cause > a problem. > > Example: > > I worked with a unit for 3 days using a customers XP desktop. > Not a hiccup. > > My partner came in and attached to the network and starting > connect to our > > appliance with his XP laptop. Within 15 minutes Zope was hung. > > > > I would strongly suspect the XP box has a b0rken TCP stack > happening. One > thing that some windows systems will do is flat out ignore the TCP > MTU/window > size settings on the network, especially if you've a) set them up > for modem > dialup b) installed anything that is supposed to automatically > improve your > internet speed c) hard wired (EVER) the MTU settings. I had a > win2k box that > had this sort of issue once, and even though it was at that time > set to use > default settings for MTU/max recieve window and the like, I had to > completely > uninstall the tcp stack, the network card driver, all modem bits > etc and > reinstall em from scratch to get it to behave normally. For the > record, > Ethereal dumps of the communications CLEARLY show that the windows > box is > using bad MTU settings and bad TCP window sizes, if this is the case. > > I *still* believe that there are settings left on that box (still > in use these > days) that cause issues periodically. Cant wait to get it out of > service > later in May. > > Hmm ... Grant T has the same drift (darn ... mail filters are > busy tonight -- > must be lots of spam in this round ... took Grants mail 6 minutes > to get into > the box after yours....) > > Alistair Tonner > > > I'm really lost. ANY ideas out there? > > Have a look at the WXP computer if patch KB893066 is installed as this one changes some default TCP window size. I had a whole LAN down before stumbling across this is one. Once removed everything worked fine. Here is the KB article from MS : http://support.microsoft.com/default.aspx?scid=kb;en-us;893066 Hope this helps you ... Enjoy your day, Bernd Lippert
