From owner-freebsd-hackers@FreeBSD.ORG Thu Jul 10 03:04:35 2003 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 3580D37B401 for ; Thu, 10 Jul 2003 03:04:35 -0700 (PDT) Received: from foem.leiden.webweaving.org (fia224-72.dsl.hccnet.nl [62.251.72.224]) by mx1.FreeBSD.org (Postfix) with ESMTP id 279F143F3F for ; Thu, 10 Jul 2003 03:04:28 -0700 (PDT) (envelope-from dirkx@webweaving.org) Received: from foem (foem [10.11.0.2])h6AA49en029268 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO); Thu, 10 Jul 2003 12:04:09 +0200 (CEST) (envelope-from dirkx@webweaving.org) Date: Thu, 10 Jul 2003 12:04:09 +0200 (CEST) From: Dirk-Willem van Gulik X-X-Sender: dirkx@foem To: Terry Lambert In-Reply-To: <3F0D3849.9E3AF6BD@mindspring.com> Message-ID: <20030710115853.O96627-100000@foem> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: freebsd-hackers@freebsd.org cc: Dan Nelson cc: Max Clark Subject: Re: What ever happened with this? "eXperimentalbandwidthdelayproduct code" X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Jul 2003 10:04:35 -0000 On Thu, 10 Jul 2003, Terry Lambert wrote: > > Okay, let's say how do I force my machine to think it doesn't have any > > latency and saturate a 6Mbit/s link even though the link has 220ms latency? > > See the recent discussion on the FreeBSD-performance mailing list. Your propblem is similar to that encountered in sat links; where you have at least a 2 x 280ms RTT's and exteremely reliable/error free 'big' links (ok, that is not quite true; but the ECC is configurable so you simply set the error rate; and use power, width and dish size amongst other as a design parameter to play iwth). Another goed overview document is best current practices for satellite links (BCP28): http://www.faqs.org/rfcs/rfc2488.html or http://mmlab.snu.ac.kr/course/AdvancedInternet/reading/SatelliteTCP.htm Alternatively if a specific protocol is involved the use of a proxy for that protocol to intentionally break end to end semantics can do wonders. We've done this in the past for protocols such as ftp, http and smtp; and it works wonders. Dw