From owner-freebsd-net@FreeBSD.ORG Thu Nov 22 17:09:07 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 CFAAC793 for ; Thu, 22 Nov 2012 17:09:07 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-we0-f182.google.com (mail-we0-f182.google.com [74.125.82.182]) by mx1.freebsd.org (Postfix) with ESMTP id 56E138FC08 for ; Thu, 22 Nov 2012 17:09:07 +0000 (UTC) Received: by mail-we0-f182.google.com with SMTP id u54so2882376wey.13 for ; Thu, 22 Nov 2012 09:09:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=DzNVzNauWYd0DC2MgK6W/L6tC93GDTeqYr/zDziTMBw=; b=xT7gxgbsj2FY3mqHAffCV03vVrdPF8qrQYjTlCa+9NaYaLRgPfrdy6QZXfmufzUiVA D+xOhLtW95xhAp7AJB14v5MUsBHYJVkNpgfoZCBqztifeSAN/7q6QBFRJ0csxCFbz0gL VqZV+m2sGce1N2Hyj9oFBiCMLdEj2t6ElvUBswN/Wq04FlEwO7r+RLbV3rEHL1cp9DcF CcVsLCSa8QNnGn1AKiBQZnr6CoJb7EKQiuHlJjoQJ+vSybjdJOdpIGghYSLpACIQgYnQ vihskY6liMODGb0zhcVc0dF8/QqhUUws0I9SpckjPAuu9zrdfAtfzttwyHlJggNQPYMB 2uFA== MIME-Version: 1.0 Received: by 10.216.139.140 with SMTP id c12mr612842wej.46.1353604146285; Thu, 22 Nov 2012 09:09:06 -0800 (PST) Sender: adrian.chadd@gmail.com Received: by 10.217.57.9 with HTTP; Thu, 22 Nov 2012 09:09:06 -0800 (PST) In-Reply-To: <50AE47D4.7080608@mpeters.org> 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> <50AE47D4.7080608@mpeters.org> Date: Thu, 22 Nov 2012 09:09:06 -0800 X-Google-Sender-Auth: UG5rgBqS09V32q3eHUSOYkyrotc Message-ID: Subject: Re: Low Bandwidth on intercontinental connections From: Adrian Chadd To: Marc Peters Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-net@freebsd.org 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 17:09:08 -0000 Hi Marc, You definitely have enough information now for a PR. Would you please file all of this into a PR so one of the IP stack people can take a look? Thanks, Adrian On 22 November 2012 07:42, Marc Peters wrote: > 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" > > _______________________________________________ > 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"