From owner-freebsd-net@FreeBSD.ORG Tue Jul 12 09:50:15 2005 Return-Path: X-Original-To: freebsd-net@freebsd.org Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7F58F16A41C; Tue, 12 Jul 2005 09:50:15 +0000 (GMT) (envelope-from dwmalone@maths.tcd.ie) Received: from salmon.maths.tcd.ie (salmon.maths.tcd.ie [134.226.81.11]) by mx1.FreeBSD.org (Postfix) with SMTP id 775D043D46; Tue, 12 Jul 2005 09:50:14 +0000 (GMT) (envelope-from dwmalone@maths.tcd.ie) Received: from walton.maths.tcd.ie ([134.226.81.10] helo=maths.tcd.ie) by salmon.maths.tcd.ie with SMTP id ; 12 Jul 2005 10:48:26 +0100 (BST) To: Danny Braniss In-reply-to: Your message of "Tue, 12 Jul 2005 12:21:23 +0300." X-Request-Do: Date: Tue, 12 Jul 2005 10:48:24 +0100 From: David Malone Message-ID: <200507121048.ab72454@salmon.maths.tcd.ie> Cc: freebsd-net@freebsd.org, freebsd-stable@freebsd.org, Luigi Rizzo Subject: Re: tcp troughput weirdness 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: Tue, 12 Jul 2005 09:50:15 -0000 > did the trick! now can someone remind me what inflight does? and could > someone explain why increasing sendspace alone did not do the trick? > (i had it at 64k, which got things better, but not sufficient). TCP inflight limiting is supposed to guess the bandwidth-delay product for a TCP connection and stop the window expanding much above this. It's a pretty neat idea for DSL links that often have huge buffers at the far end, where inflight limiting can prevent delays to interactive traffic. However, some of the guys I know that work on TCP dynamics reckon that they can they can come up with situations where inflight limiting will break. Unfortunately, I haven't had time to talk this through with them. I guess you may have found one of those situations ;-) David.