From owner-freebsd-net@FreeBSD.ORG Fri May 11 05:23:03 2007 Return-Path: X-Original-To: freebsd-net@freebsd.org 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 5D6A116A400 for ; Fri, 11 May 2007 05:23:03 +0000 (UTC) (envelope-from suvashrestha@wlink.com.np) Received: from smtp5.wlink.com.np (smtp5.wlink.com.np [202.79.32.52]) by mx1.freebsd.org (Postfix) with SMTP id 44DD213C44B for ; Fri, 11 May 2007 05:23:00 +0000 (UTC) (envelope-from suvashrestha@wlink.com.np) Received: (qmail 98986 invoked from network); 11 May 2007 05:22:47 -0000 Received: from unknown (HELO smtp1.wlink.com.np) (202.79.32.76) by 0 with SMTP; 11 May 2007 05:22:47 -0000 Received: (qmail 81206 invoked by uid 98); 11 May 2007 05:22:47 -0000 Received: from 202.79.32.67 by smtp1.wlink.com.np (envelope-from , uid 1009) with qmail-scanner-1.25 (clamdscan: 0.88.4/2205. Clear:RC:1(202.79.32.67):. Processed in 0.58594 secs); 11 May 2007 05:22:47 -0000 X-Qmail-Scanner-Mail-From: suvashrestha@wlink.com.np via smtp1.wlink.com.np X-Qmail-Scanner: 1.25 (Clear:RC:1(202.79.32.67):. Processed in 0.58594 secs) Received: from [202.79.32.67] (HELO webmail.wlink.com.np) by smtp1.wlink.com.np (qmail-smtpd) with SMTP; 11 May 2007 05:22:45 -0000 (Fri, 11 May 2007 11:07:45 +0545) Received: from 202.79.36.118 (auth. user suvashrestha@pop3.wlink.com.np) by webmail.wlink.com.np with HTTP; Fri, 11 May 2007 10:22:43 +0500 To: freebsd-net@freebsd.org Date: Fri, 11 May 2007 10:22:43 +0500 X-Mailer: IlohaMail/0.8.14 (On: webmail.wlink.com.np) Message-ID: In-Reply-To: From: Bounce-To: Errors-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Spam-Check-By: smtp1.wlink.com.np Spam: No ; -0.8 / 7.0 X-Spam-Status-WL: No, hits=-0.8 required=7.0 Subject: bridge query X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 May 2007 05:23:03 -0000 Hello.... I am using TCP sockets to measure packet transfer. And I am also not looking to optimise the link. I just want to know if this is the usual behaviour of the freeBSD TCP or bridge when we apply delay and packet loss. The throughtput falls from around 8 Mbps (8000 Kbps) to just 80 Kbps. This is very significant. Thanks suva How are you measuring packet transfer (single TCP socket, multiple TCP sockets or UDP) and what were you expecting? For a TCP connection, the window size needs to be able to handle at least 1 RTT (0.5 second in this case) of data. This translates to a total of 5Mb (~640KB) outstanding data to get 10Mbps throughput. With only a single cnnection, you would need a 640KB window size - which is far larger (an order of magnitude or so) than typical. TCP is also designed to work on a mostly lossless link. I am not sure how much a 5% packet loss will affect it but I would expect it to be significant. I'm not sure how to optimise throughput in this situation. Peter Jeremy