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Message-ID: <4CEEE0BB.6020509@gmail.com>
Date: Thu, 25 Nov 2010 23:18:35 +0100
From: Jarek Poplawski <jarkao2@gmail.com>
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To: Ben Gamari <bgamari@gmail.com>
CC: Mike Caoco <caoco2002@yahoo.com>,
        Stephen Hemminger <shemminger@vyatta.com>,
        Netdev <netdev@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: Unplug ethernet cable, the route persists.  Why?
References: <144174.46619.qm@web63401.mail.re1.yahoo.com> <87bp5df9j9.fsf@gmail.com>
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Ben Gamari wrote:
> On Wed, 24 Nov 2010 12:29:43 -0800 (PST), Mike Caoco <caoco2002@yahoo.com> 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.
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