On Fri, Oct 11, 2013 at 10:59:51AM -0400, Andy M. wrote: > I looked at my pcap file again. It looks really weird. My HAProxy gets > the GET request, and sends the response. The the client resends the GET > request, and there seems to be a lot of tcp_retransmission and dup ack > packets. Here is a picture of one request to my haproxy: > > http://i.imgur.com/r3oz6lz.png > > Any clue what would cause that problem?
Yes, a typical packet loss between you and the client. > I tried to change the max_syn_backlog, and somaxconn values to both > 10240/20480 and 262144/262144, neither seemes to have solved the problem. Here it's not the SYN backlog since it's the HTTP request that is retransmitted. It is possible that your network interface has a defect. It happened to me once, in a batch of 10 NICs, 3 had defective RAM chips which would randomly corrupt outgoing packets. Try to use another interface or another switch port. > Conntrack is not loaded, I checked this a while ago, and I am not using > anything that would load it. Here are the commands below. It also doesn't > look like anything is being dropped. The interface I am using is bond1. Great, since you're using bonding, it's easy to switch to the other NIC and see if it works better. >From your stats, I'm assuming you're not running with both NICs attached to the same bond in round robin. I was just checking, because doing so would expose you to a high probability of disordering packets, which some firewalls generally don't accept and will block, causing the client to retransmit. I think now you need to sniff closer to the client to see where the packets are lost. If you can make a span on your switch to check if it correctly receives them, that will help you. Willy
