From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from shiva.jussieu.fr (shiva.jussieu.fr [134.157.0.129]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 813F820131D for ; Wed, 22 Jun 2011 06:43:22 -0700 (PDT) Received: from hydrogene.pps.jussieu.fr (hydrogene.pps.jussieu.fr [134.157.168.1]) by shiva.jussieu.fr (8.14.4/jtpda-5.4) with ESMTP id p5MDdise015997 ; Wed, 22 Jun 2011 15:39:57 +0200 (CEST) X-Ids: 168 Received: from lanthane.pps.jussieu.fr (lanthane.pps.jussieu.fr [134.157.168.57]) by hydrogene.pps.jussieu.fr (Postfix) with ESMTPS id C3BB4C2E53; Wed, 22 Jun 2011 15:39:43 +0200 (CEST) Received: from jch by lanthane.pps.jussieu.fr with local (Exim 4.76) (envelope-from ) id 1QZNeh-00013i-Es; Wed, 22 Jun 2011 15:39:43 +0200 From: Juliusz Chroboczek To: Dave Taht Subject: Re: battling with babel and route changes References: Date: Wed, 22 Jun 2011 15:39:43 +0200 In-Reply-To: (Dave Taht's message of "Sun, 19 Jun 2011 07:44:53 -0600") Message-ID: <7ipqm6c7ds.fsf@lanthane.pps.jussieu.fr> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Miltered: at jchkmail.jussieu.fr with ID 4E01F0A0.005 by Joe's j-chkmail (http : // j-chkmail dot ensmp dot fr)! X-j-chkmail-Enveloppe: 4E01F0A0.005/134.157.168.1/hydrogene.pps.jussieu.fr/hydrogene.pps.jussieu.fr/ Cc: bloat-devel@lists.bufferbloat.net, babel-users@lists.alioth.debian.org X-BeenThere: bloat-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: "Developers working on AQM, device drivers, and networking stacks" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Jun 2011 13:43:23 -0000 [Added babel-users to the CC, with permission from Dave.] > 0) babel keeps all the routing information in it's head. It does not > use the kernel metrics in particular: Yes. That's by design. The ``kernel metric'' is something of a misnomer: it's not a metric, it's better understood as a priority. It's only useful to discriminate between routes with the same destination that are installed by different routing protocols. It's analogous to what Cisco call the ``Administrative Distance''. You can choose the kernel priority used by Babel with the -k command-line option. If you need finer-grained control on routing than possible with -k alone, -t and -T together with ``ip table'' and friends are what you need. A patch to reflect the metric in the kernel priority has been published on this list at some point; I'll not be merging it into Babel, since I remain convinced that that's the wrong thing to do. > 1) babel installs ipv4 routes with a metric of 0, ipv6 routes with a > metric of 1024 These are apparently the kernel's defaults -- we call the kernel with the value 0 in both cases. You can set the priority with -k (but cannot set it to be different between v4 and v6), and if you need any more control, use routing tables (-t and -T). -- Juliusz