Date: Fri, 23 Feb 2007 02:17:15 -0500 From: Andre Guibert de Bruet <andy@siliconlandmark.com> To: Andre Oppermann <andre@freebsd.org> Cc: Andrew Gallatin <gallatin@cs.duke.edu>, current@freebsd.org Subject: Re: excessive TCP duplicate acks? Message-ID: <566BDEAE-5E29-4B35-AF30-37DBADD19FBE@siliconlandmark.com> In-Reply-To: <45DC679A.9030304@freebsd.org> References: <17850.13146.266196.499166@grasshopper.cs.duke.edu> <2FE2BC67-A829-4BF9-B606-65DE1393E8DE@siliconlandmark.com> <17883.19584.99616.808623@grasshopper.cs.duke.edu> <DF12957F-D92B-495A-A815-2F5ECFD83852@siliconlandmark.com> <45DC679A.9030304@freebsd.org>
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On Feb 21, 2007, at 10:39 AM, Andre Oppermann wrote: > Andre Guibert de Bruet wrote: >> On Feb 20, 2007, at 2:31 PM, Andrew Gallatin wrote: >>> Thanks for reporting this. I'm glad I'm not the only one who is >>> seeing this! >> I discovered this while testing out a new multi-homed bonded-T1 >> installation. I was wondering why I was getting no more than >> ~170KB/ s. So far, here are the data points that I have gathered: >> - It affects more than one type of NIC (em0). >> - It happens regardless of hardware checksum enabled status. >> - It happens independent of IP aliasing. >> - I tested GENERIC as of Feb 19 and it is affected. >> - A kernel from December 15th, 2006 exhibits this problem. >> - The affected system is connected to a Linksys 24-port unmanaged >> gigabit switch (I have the exact same hardware working just fine >> with 5.5-STABLE on the same switch). > > Today I finally got some spare time and tried to track this down. > However > there is no obvious smoking gun to be seen. I'll dig further. Andre, Just as a followup to my off-list email: I have since come across kern/102653. Though my setup uses stateful inspection rules exclusively, the problem still persists with "allow ip from any to any" as the single rule in ipfw. I have a pcap of the traffic patterns that I am seeing, at http://siliconlandmark.com/staff/andre/ files/7-current_dupacks.pcap (2.3MB - This pcap was made with the single allow any to any rule). Andy /* Andre Guibert de Bruet * 6f43 6564 7020 656f 2e74 4220 7469 6a20 */ /* Code poet / Sysadmin * 636f 656b 2e79 5320 7379 6461 696d 2e6e */ /* GSM: +1 734 846 8758 * 5520 494e 2058 6c73 7565 6874 002e 0000 */ /* WWW: siliconlandmark.com * C/C++, Java, Perl, PHP, SQL, XHTML, XML */
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