I need to increase throughput for long lived tcp connections over ipsec over wan between Amazon in Ireland and a Level3 gigabit link in Ashburn Virginia (currently running at about 20Mbps). I've read various articles saying to enlarge the buffers and make various other kernel tweaks. Some say to base it on the bandwidth delay product, some say just on the link speed, and some say don't bother linux does all that automatically now. Alot of it seems random.
However, with wireshark I see that the "bytes in flight" measurement which counts unacknowledged bytes from the source never gets close to the window size sent by the destination. Does this suggest anything in particular to tweak? I got some books on wireshark, which were quite helpful in how to use the graphs and filters, but on tcp performance they mostly just talked about the effect of packet loss. I'm not certain, but I don't think packet loss is the main thing holding back my performance, because there is some which causes a brief dip in the window size and then it recovers. Throughput stays pretty flat. It would be really amazing if there was a flowchart on doing this for linux that could be informed by wireshark io graphs and other graphs. Has anybody ever seen such a chart? If this approach is succesful for me, and I can understand how to do it in several scenarios, I think I will even like to make such a flow chart if it doesn't already exist. Thanks for any tips and disabusement of my misunderstandings about tcp in linux :) Nick _______________________________________________ vox-tech mailing list [email protected] http://lists.lugod.org/mailman/listinfo/vox-tech
