From owner-freebsd-net@FreeBSD.ORG  Sun May 21 09:26:11 2006
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
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 4D3BA16A420
	for <freebsd-net@freebsd.org>; Sun, 21 May 2006 09:26:11 +0000 (UTC)
	(envelope-from b.candler@pobox.com)
Received: from rune.pobox.com (rune.pobox.com [208.210.124.79])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 2200343D6E
	for <freebsd-net@freebsd.org>; Sun, 21 May 2006 09:26:07 +0000 (GMT)
	(envelope-from b.candler@pobox.com)
Received: from rune (localhost [127.0.0.1])
	by rune.pobox.com (Postfix) with ESMTP id 3AADD7881D;
	Sun, 21 May 2006 05:26:28 -0400 (EDT)
Received: from mappit.local.linnet.org (212-74-113-67.static.dsl.as9105.com
	[212.74.113.67])
	(using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
	(No client certificate requested)
	by rune.sasl.smtp.pobox.com (Postfix) with ESMTP id D801678814;
	Sun, 21 May 2006 05:26:25 -0400 (EDT)
Received: from lists by mappit.local.linnet.org with local (Exim 4.61
	(FreeBSD)) (envelope-from <b.candler@pobox.com>)
	id 1FhkCI-0005Hm-9C; Sun, 21 May 2006 10:26:02 +0100
Date: Sun, 21 May 2006 10:26:02 +0100
From: Brian Candler <B.Candler@pobox.com>
To: Mike Tancsa <mike@sentex.net>
Message-ID: <20060521092602.GB20262@uk.tiscali.com>
References: <6.2.3.4.0.20060519110026.05820230@64.7.153.2>
	<Pine.BSF.3.96.1060520014045.15967A-100000@gaia.nimnet.asn.au>
	<6.2.3.4.0.20060519121104.1126b480@64.7.153.2>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <6.2.3.4.0.20060519121104.1126b480@64.7.153.2>
User-Agent: Mutt/1.4.2.1i
Cc: freebsd-net@freebsd.org, Ian Smith <smithi@nimnet.asn.au>
Subject: Re: improving transport over lossy links ?
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 21 May 2006 09:26:11 -0000

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.

Regards,

Brian.