Hi Wolfgang, On Tue, Mar 27, 2012 at 12:45:25PM +0200, Wolfgang Engel wrote: > Hi, > > I just want to follow up on a thread from december 2011 where Simon > experienced problems regarding TCP retransmissions. > > We are seeing this problem on our site (susestudio.com) as well for > upload/download since we are using haproxy version 1.5-dev7 on > SLES11SP1 with kernel version 2.6.32.54-0.3-default. > Not all users seems to be affected and it is hard to reproduce since it > happens randomly. > I switched off TCP segment offload like Willy suggested for testing. > > I can provide tcpdump of some interrupted download transfer from our > site where you might have a look at. > > Does someone else experience this problem ?
Just for the record, Simon's issue was caused by an overzealous cisco firewall performing deep inspection but not exactly knowing the HTTP protocol, resulting in some WebSocket communications being blocked on port 80 (since it does not inspect other ports). Another user, Jason Strimpel faced the exact same issue with WebSocket, this time with a TrendMicro Officescan firewall installed on the client machine. Same observation, by switching to another port everything went smooth. So I'm not sure you're discussing exactly the same kind of issues, but just in case I'd be very interested in getting a trace showing these retransmits, and if possible a few session before related to the same source IP. It is indeed possible that what you're seeing is related to an incompatibility between your local TCP stack and the other side's, which unfortunately happens to be more and more common with mobile operators doing funny things in order to offer connectivity to more users than they have available IP addresses. Best regards, Willy
