From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Priebe - Profihost AG Subject: slow TCP speed through linux ip forwarding Date: Tue, 16 Jun 2015 12:35:06 +0200 Message-ID: <557FFBDA.9040501@profihost.ag> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org Return-path: Received: from mail-ph.de-nserver.de ([85.158.179.214]:57923 "EHLO mail-ph.de-nserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754605AbbFPKfH (ORCPT ); Tue, 16 Jun 2015 06:35:07 -0400 Sender: netdev-owner@vger.kernel.org List-ID: Hello, i hope somebody has an idea for my problem and may point me to the right direction. Alle servers run kernel 3.18.14. My problem is that i can't archieve more than 20Mbit/s using a single TCP stream and i've no further ideas how to solve it. reduced Network Map Server A | Linux GW Server | Brocade Router - Server B | Internet | Server C The Linux GW Server does nothing more than being an ip forwarding GW. (no iptables / packet filtering). I've done the following Tests while the Linux GW has a traffic of around 500-600Mbit/s: Download file from Server A to C: 10-20Mbit/s Download file from Server A to B: 100Mbit/s Download file from Server B to C: 100Mbit/s 4 parallel downloads from Server A to C: 80-100Mbit/s Same test with no other traffic on the Linux GW: Download file from Server A to C: 100Mbit/s Download file from Server A to B: 100Mbit/s Download file from Server B to C: 100Mbit/s 4 parallel downloads from Server A to C: 100Mbit/s Same test with net.ipv4.tcp_congestion_control=bic on Server A: Download file from Server A to C: 70Mbit/s Download file from Server A to B: 100Mbit/s Download file from Server B to C: 100Mbit/s 4 parallel downloads from Server A to C: 80-100Mbit/s ehtootl -S shows no errors for eth0 and eth1 on the linux gw. I've no further ideas. Thanks a lot. Greets, Stefan