From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ed Wildgoose Date: Tue, 22 Jun 2004 09:29:05 +0000 Subject: Re: [LARTC] Modems: Cable or DSL digital blunders that lartc may Message-Id: <40D7FBE1.3010607@wildgooses.com> List-Id: References: <20040622043359.75922.qmail@web11905.mail.yahoo.com> In-Reply-To: <20040622043359.75922.qmail@web11905.mail.yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lartc@vger.kernel.org Hi Mike, >I have a Cable 'modem' that has a problem that many of these devices is >bound to have. I was wondering what other lartc user thought about this >and if DSL has simular problems. > > Yep, we all have this problem. Read through LARTC, ADSL_QOS howto and even some recent posts to this list (which cover this in great detail) >Cable, being Asymetrical, is able to upload at a given rate and hopefully >has a buffer, in the modem, of some kind. When I nc(netcat) to a UDP >echo, or discard, server I get about 10Mbps out on my ethernet, but only >256Kbps acctualy receved(reported by an open echo server). Other traffic >on the link suffers grately from this, so I don't do it oftan :) I use >htb to curve this and that seams to work nice. > >NO REALY MY CABLE MODEM DOSEN'T MAKE ANY ATTEMPT TO, CALL FOR HELP, >CONTROL THE FLOW(aka flow-control, supported by ethernet and rs-232). > > There is no such flowcontrol in ethernet or rs232. TCP only indicates congestion by dropping packets. There is something called ECN, but it is rarely implemented (and tests suggest that it doesn't help as much as theory might like). Read the LARTC and come back for more. It's a really great document Ed W _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/