From owner-freebsd-net@FreeBSD.ORG Thu Nov 22 15:42:22 2012 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 1E434C2F for ; Thu, 22 Nov 2012 15:42:22 +0000 (UTC) (envelope-from marc@mpeters.org) Received: from mail.mpeters.org (mail.mpeters.org [78.46.104.142]) by mx1.freebsd.org (Postfix) with ESMTP id C193F8FC17 for ; Thu, 22 Nov 2012 15:42:21 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mail.mpeters.org (Postfix) with ESMTP id DC256132011 for ; Thu, 22 Nov 2012 16:42:14 +0100 (CET) X-Virus-Scanned: amavisd-new at mpeters.org Received: from mail.mpeters.org ([127.0.0.1]) by localhost (mail.mpeters.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id kPC2ysm4I6hR for ; Thu, 22 Nov 2012 16:42:13 +0100 (CET) Received: from [192.168.0.204] (unknown [62.159.86.18]) by mail.mpeters.org (Postfix) with ESMTPSA id 02C1513200E for ; Thu, 22 Nov 2012 16:42:12 +0100 (CET) Message-ID: <50AE47D4.7080608@mpeters.org> Date: Thu, 22 Nov 2012 16:42:12 +0100 From: Marc Peters User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121104 Thunderbird/16.0.1 MIME-Version: 1.0 To: freebsd-net@freebsd.org Subject: Re: Low Bandwidth on intercontinental connections References: <50ACF62C.8000408@mpeters.org> <50ad087d.1892cc0a.2cce.3bf2@mx.google.com> <50AD1012.7020209@mpeters.org> <50AD14F8.8050001@xip.at> <50ADE5E4.9090708@mpeters.org> <50AE0B12.8000309@xip.at> <50AE1CCC.7080706@mpeters.org> <50AE2686.8070007@xip.at> In-Reply-To: <50AE2686.8070007@xip.at> X-Enigmail-Version: 1.5a1pre Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Nov 2012 15:42:22 -0000 On 11/22/2012 02:20 PM, Ingo Flaschberger wrote: > Am 22.11.2012 13:38, schrieb Marc Peters: >> interesting, the MTU is way lower, than i expected. Through the VPN >> tunnel, only 1322 bytes are possible without fragmentation. ScreenOS >> adds 42 additional bytes per paket and the FreeBSD box is receiving >> 1364 bytes, according to tcpdump. From the outside (only one Netscreen >> on the way), 1472 is the maximum possible size to send pakets without >> fragmentation (-D). Which MTU would you suggest to use? Shouldn't the >> MTU discovery of FreeBSD handle this correct? > > do you see fragmented tcp packets on the receiving site in tcpdump? nearly every packet is fragmented, if i read th [TCP segment of a reassembled PDU] correct. Those have a length of 1364. Thera are also lots of [TCP Window Update] (every two to three acks from the receiving host, where the tcpdump took place). After some time, there were lots of [TCP Dup ACK] from the receiving host and the throughput went to a crawl and had lots of retransmissions. After 30 sec. everything went back to "normal" as of transmitting pakets without dubs and retransmissions. The same tcpdump collect on the Linux hosts, the packets had a length of 1514 and no dubs or retransmissions. I didn't get the option JUMBO_MTU removed, but removing TSO4 didn't changed anything. Adding packetfiltering and the pipe didn't change anything, too. > > When you load the tcpdump data (tcpdump -s 1500 -w filename ...) into > wireshark, you can graph the speed (bit/sec, packets/sec) and do some > more tcp analysis. > > Kind regards, > Ingo Flaschberger > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"