From owner-freebsd-stable@FreeBSD.ORG Tue Jan 23 19:22:56 2007 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 9FB9816A407 for ; Tue, 23 Jan 2007 19:22:56 +0000 (UTC) (envelope-from jandrese@mitre.org) Received: from smtp-mclean.mitre.org (smtpproxy2.mitre.org [192.80.55.71]) by mx1.freebsd.org (Postfix) with ESMTP id 6203E13C44C for ; Tue, 23 Jan 2007 19:22:56 +0000 (UTC) (envelope-from jandrese@mitre.org) Received: from smtp-mclean.mitre.org (localhost.localdomain [127.0.0.1]) by smtp-mclean.mitre.org (8.12.11.20060308/8.12.11) with SMTP id l0NJMtu3013530 for ; Tue, 23 Jan 2007 14:22:55 -0500 Received: from smtp-mclean.mitre.org (localhost.localdomain [127.0.0.1]) by smtp-mclean.mitre.org (Postfix) with ESMTP id 601721BD7C for ; Tue, 23 Jan 2007 14:22:55 -0500 (EST) Received: from imcfe2.MITRE.ORG (imcfe2.mitre.org [129.83.29.4]) by smtp-mclean.mitre.org (8.12.11.20060308/8.12.11) with ESMTP id l0NJMtKD013527 for ; Tue, 23 Jan 2007 14:22:55 -0500 Received: from IMCSRV6.MITRE.ORG ([129.83.20.237]) by imcfe2.MITRE.ORG with Microsoft SMTPSVC(6.0.3790.1830); Tue, 23 Jan 2007 14:22:55 -0500 X-MimeOLE: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Date: Tue, 23 Jan 2007 14:22:54 -0500 Message-ID: <53B52415C756A84E8A169F0E3673A3290E8BA4@IMCSRV6.MITRE.ORG> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: Dummynet and simulating random delay thread-index: Acc/I+FRI1NKfsplS6GVSLJ+SmRh9A== From: "Andresen, Jason R." To: X-OriginalArrivalTime: 23 Jan 2007 19:22:55.0037 (UTC) FILETIME=[E1F036D0:01C73F23] Subject: Dummynet and simulating random delay X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Jan 2007 19:22:56 -0000 I have a project that requires me to simulate a link with varying but well defined delay. The link is guarenteed to deliver packets in order, so I wish to maintain that behavior with Dummynet. My first thought was to create three or four different queues with different delays and use the probability rule to dump them into the queue, but that gets packets out of order and doesn't work. =20 My next thought is to write a script that reconfigures the pipe randomly every few hundred milliseconds or so during the test, but I'm not sure what that means for packets that are already in it. Does it mean bursts of data when the delay is turned down (which would actually be realistic in this scenario), or is there a danger of out of order packets? Are there any dummynet experts out there that can tell me exactly how it will behave when delays are changed while there are still packets in the buckets? Thanks.