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Date:      Fri, 27 Jul 2001 08:08:56 -0300
From:      "Daniel C. Sobral" <daniel.sobral@tcoip.com.br>
To:        zebra@zebra.org, net@freebsd.org
Subject:   Re: [zebra 9651] RE: Linux/Ethernet interface status? Linux & BSD
Message-ID:  <3B614BC8.7040904@tcoip.com.br>
References:  <FDEDA1BCEEBFD4118FFB00508BB1940B03419292@eahq-mb2>

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Bulger, Tim wrote:

> Well, the verdict is in... FreeBSD does know the interface status (per
> ifconfig), but neither the kernel nor zebra reacts to the cable being
> pulled.  This seems basically broken from a kernel perspective.  It doesn't
> make sense to retain connected and/or static routes in the routing table for
> an interface that is down.  If you have two static routes for the same
> network with different metrics as a simple failover scheme, it will not work
> on these systems because the route with the lower metric is never removed
> from the table.......  Perhaps this is OK from a workstation perspective,
> but this is not suitable for a router.  I will be investigating ways to work
> around this problem without compromising sanity.

The kernel _should not_ react in any such way. In first place, an "no 
route to host" error is a very different one from lost packets, so the 
kernel must not presume any knowledge of what you want. Second, if it 
deletes the static routes it will not know what these are when the 
interface conectivity is restored.

A routing demon, such as Zebra, would be in a proper place to take 
decisions like this.

This would be an ideal application for kqueue. Is there any kqueue 
events for interface status?

-- 
Daniel C. Sobral                   (8-DCS)
Daniel.Sobral@tcoip.com.br
dcs@newsguy.com
dcs@freebsd.org
capo@notorious.bsdconspiracy.net

Maybe Computer Science should be in the College of Theology.
		-- R. S. Barton


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