From owner-freebsd-net@FreeBSD.ORG Sun May 21 15:49:27 2006 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 A6AB016A433 for ; Sun, 21 May 2006 15:49:27 +0000 (UTC) (envelope-from bv@bilver.wjv.com) Received: from wjv.com (fl-65-40-24-38.sta.sprint-hsd.net [65.40.24.38]) by mx1.FreeBSD.org (Postfix) with ESMTP id 80B5F43D6A for ; Sun, 21 May 2006 15:49:26 +0000 (GMT) (envelope-from bv@bilver.wjv.com) Received: from bilver.wjv.com (localhost.wjv.com [127.0.0.1]) by wjv.com (8.13.6/8.13.1) with ESMTP id k4LFnNYh002144; Sun, 21 May 2006 11:49:23 -0400 (EDT) (envelope-from bv@bilver.wjv.com) Received: (from bv@localhost) by bilver.wjv.com (8.13.6/8.13.1/Submit) id k4LFnHoL002143; Sun, 21 May 2006 11:49:17 -0400 (EDT) (envelope-from bv) Date: Sun, 21 May 2006 11:49:17 -0400 From: Bill Vermillion To: Mike Tancsa Message-ID: <20060521154917.GB2053@wjv.com> References: <6.2.3.4.0.20060519110026.05820230@64.7.153.2> <6.2.3.4.0.20060519121104.1126b480@64.7.153.2> <20060521092602.GB20262@uk.tiscali.com> <6.2.3.4.0.20060521104147.081af2d8@64.7.153.2> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6.2.3.4.0.20060521104147.081af2d8@64.7.153.2> Organization: W.J.Vermillion / Orlando - Winter Park ReplyTo: bv@wjv.com User-Agent: Mutt/1.5.11 X-Spam-Status: No, score=-4.4 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.1.1 X-Spam-Checker-Version: SpamAssassin 3.1.1 (2006-03-10) on bilver.wjv.com Cc: freebsd-net@freebsd.org, Ian Smith , Brian Candler Subject: Re: improving transport over lossy links ? X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: bv@wjv.com List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 21 May 2006 15:49:36 -0000 Throwing caution to the wind and speaking without thinking about what was being said on Sun, May 21, 2006 at 11:09 , Mike Tancsa blurted this: > At 05:26 AM 21/05/2006, Brian Candler wrote: > >On Fri, May 19, 2006 at 12:38:31PM -0400, Mike Tancsa wrote: > >> Thanks for the reply. Even at 28.8 I am seeing loss with > >> the connection dropping and seeing dropped packets (e.g. > >> May 19 12:04:43 soekris4801 ppp[3404]: tun0: Phase: 1: HDLC errors -> > >> FCS: 1, ADDR: 0, COMD: 0, PROTO: 0) > >If you have an error-correcting modem, but you are seeing data corruption, > >then I'd expect the data corruption is occuring on the RS232 link between > >the PC and the modem at one end or the other. You may have a handshaking > >problem (i.e. ensure the modem is configured for CTS/RTS handshaking, and > >the port is configured for this too; with pppd it's "crtscts", I don't know > >about userland ppp; and ensure the cables are wired properly) > >If your app could cope with the lack of bandwidth, forcing the modems to > >2400bps operation can make links over dodgy lines a lot more reliable. > > Hi, > Its not so much data corruption of packets on the wire, but > the modem dropping the connection, retraining and > renegotiating. When the retrains and re negotiations happen, this > can cause problems for the VPN as keep alives are missed, tx buffers > can fill up etc. I have tried a number of modems, the current one > being U.S. Robotics 56K FAX INT V5.22.70. and I am also trying an > external Intel at the office The best modems I've found are the ones from Multi-tech. Even their super-small ones. Before we added a PRI and a Livingston we were thinking about using the MT's in the 19" rack mount box they have. And when performing fax from email - using sendmail incoming and routing to fax [in the early days of the current 'net before many people had 'net connections] the MT's were the only ones that worked with virtually ever target fax machine. The MTs are external. Bill -- Bill Vermillion - bv @ wjv . com