From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Furniss Date: Thu, 02 Mar 2006 21:35:35 +0000 Subject: Re: [LARTC] Patch to allow for the ATM "cell tax" Message-Id: <44076527.9030402@dsl.pipex.com> List-Id: References: <1141284603.10264.168.camel@ras.pc.brisbane.lube> In-Reply-To: <1141284603.10264.168.camel@ras.pc.brisbane.lube> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lartc@vger.kernel.org Adam James wrote: > As Markus mentioned in another post on this thread, Jesper Dangaard > Brouer (http://www.adsl-optimizer.dk) has already written an iproute2 > and Linux kernel patch that implements the above. ATM cell alignment is > done in tc_core.c, and the per packet overhead is passed to the relevant > kernel modules. > > I have made some very minor changes to the patches, so that they apply > cleanly to iproute2-20051007 and kernel 2.6.15. You will find them > attached to this mail. Just remember to take 14 from your overhead if your modem is connected via eth rather than ppp etc. This means you need to put a negative overhead (can you?) if using pppoa/vcmux > Setting the MTU to 1478 is probably a good idea to prevent excessive > cell usage. Reasoning behind this being: 1488 is the largest multiple of > 48 under 1500, less 2 bytes for the PPP header and 8 for the AAL5 > footer. > > Perhaps you can confirm this isn't way off the mark Andy? :) 1478 is optimal if your overhead is 10 - I use it. For the pppoes I don't think you gain much as you loose tcp data efficiency by using smaller packets. Andy. _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc