From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: Re: [PATCH 0/2] NET: Accurate packet scheduling for ATM/ADSL Date: Wed, 14 Jun 2006 17:08:28 +0200 Message-ID: <1150297708.26187.125.camel@localhost.localdomain> References: <1150278004.26181.35.camel@localhost.localdomain> <44901CC1.60403@cfl.rr.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-4ffjErETNjtEUGjcGhsY" Cc: netdev@vger.kernel.org, russell-tcatm@stuart.id.au, hawk@diku.dk Return-path: Received: from ex001a.cxnet.dk ([195.135.216.13]:54788 "EHLO comxexch01.comx.local") by vger.kernel.org with ESMTP id S964995AbWFNPI3 (ORCPT ); Wed, 14 Jun 2006 11:08:29 -0400 To: Phillip Susi In-Reply-To: <44901CC1.60403@cfl.rr.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org --=-4ffjErETNjtEUGjcGhsY Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Wed, 2006-06-14 at 10:27 -0400, Phillip Susi wrote: > Jesper Dangaard Brouer wrote: > > The Linux traffic's control engine inaccurately calculates > > transmission times for packets sent over ADSL links. For > > some packet sizes the error rises to over 50%. This occurs > > because ADSL uses ATM as its link layer transport, and ATM > > transmits packets in fixed sized 53 byte cells. > >=20 >=20 > I could have sworn that DSL uses its own framing protocol that is=20 > similar to the frame/superframe structure of HDSL ( T1 ) lines and over=20 > that you can run ATM or ethernet. Or is it typically ethernet -> ATM ->=20 > HDSL? Nope, not according to the ADSL standards G.992.1 and G.992.2. > In any case, why does the kernel care about the exact time that the IP=20 > packet has been received and reassembled on the headend? I think you have misunderstood what the rate table does... (There is an explaination in the thesis page 57 section 6.1.2) http://www.adsl-optimizer.dk/thesis/ --=20 Med venlig hilsen / Best regards Jesper Brouer ComX Networks A/S Linux Network developer Cand. Scient Datalog / MSc. Author of http://adsl-optimizer.dk --=-4ffjErETNjtEUGjcGhsY Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQBEkCZswuVH+NB3fZkRAo+kAJ43vH6ref8tpO9MshfbuNvjQm4krACgifVG i8MDQxfwLjwJ8KQ2DN9w6B4= =Q6jF -----END PGP SIGNATURE----- --=-4ffjErETNjtEUGjcGhsY--