From owner-freebsd-net@FreeBSD.ORG Mon Apr 30 12:17:48 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 849A916A400 for ; Mon, 30 Apr 2007 12:17:48 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from cyrus.watson.org (cyrus.watson.org [209.31.154.42]) by mx1.freebsd.org (Postfix) with ESMTP id 18E9413C43E for ; Mon, 30 Apr 2007 12:17:47 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from fledge.watson.org (fledge.watson.org [209.31.154.41]) by cyrus.watson.org (Postfix) with ESMTP id 64181475C4; Mon, 30 Apr 2007 08:17:46 -0400 (EDT) Date: Mon, 30 Apr 2007 13:17:46 +0100 (BST) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: Peter Jeremy In-Reply-To: <20070430113715.GD838@turion.vk2pj.dyndns.org> Message-ID: <20070430131317.B9647@fledge.watson.org> References: <20070429112838.GH848@turion.vk2pj.dyndns.org> <20070430105659.C37507@fledge.watson.org> <20070430113715.GD838@turion.vk2pj.dyndns.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: Jack Barnett , freebsd-net@freebsd.org Subject: Re: Firewall 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: Mon, 30 Apr 2007 12:17:48 -0000 On Mon, 30 Apr 2007, Peter Jeremy wrote: > On 2007-Apr-30 10:58:18 +0100, Robert Watson wrote: > >> One of the big selling points of IPFW is integration with DUMMYNET, which >> offers bandwidth management facilities not present in the other systems. > > I thought altq(4) could also do most of what dummynet(4) does but based on a > closer look, it seems that it can't do the packet delay stuff, though it > seems to have fairly similar bandwidth management facilities. altq(4) as implemented on FreeBSD operates on outbound network interface queues. This limits its utility significantly: (1) It does not affect inbound network traffic at all, so for non-routers, you can't control the way inbound traffic appears to the stack, only replies. (2) Most modern network hardware effectively places these queues in hardware, especially if not running completely saturated. Robert N M Watson Computer Laboratory University of Cambridge