From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: Unplug ethernet cable, the route persists. Why? Date: Thu, 25 Nov 2010 23:18:35 +0100 Message-ID: <4CEEE0BB.6020509@gmail.com> References: <144174.46619.qm@web63401.mail.re1.yahoo.com> <87bp5df9j9.fsf@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Mike Caoco , Stephen Hemminger , Netdev , LKML To: Ben Gamari Return-path: Received: from mail-wy0-f174.google.com ([74.125.82.174]:46524 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752387Ab0KYWSl (ORCPT ); Thu, 25 Nov 2010 17:18:41 -0500 In-Reply-To: <87bp5df9j9.fsf@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Ben Gamari wrote: > On Wed, 24 Nov 2010 12:29:43 -0800 (PST), Mike Caoco wrote: >> So if you rely on NetworkManager or Connman or Quagga to remove the >> route, the routing daemons will recompute the route table anyway. So >> why cannot this be done in the kernel? > > This is policy. In the Linux world we generally strive to separate > policy from mechanism, leaving the former to userspace. This allows > (potentially complex) policy decisions to be made in user-space. The > reason for this is two-fold: First, every line of kernel code introduces > the potentially for a bug and error handling in the kernel is generally > more complex than it is in user-space. Secondly, allowing user-space to > handle policy allows users to do things with the kernel that kernel > developers did not envision. This flexibility is one reason why the > kernel is so suited for running on anything from your cell-phone to 4000 > processor big iron. Secondly and a half, if you add a specific route you may really mean it, and prefer not to send at all than use default. Cheers, Jarek P.