From owner-freebsd-net Tue Jun 29 17:10:41 1999 Delivered-To: freebsd-net@freebsd.org Received: from xylan.com (postal.xylan.com [208.8.0.248]) by hub.freebsd.org (Postfix) with ESMTP id A7DA9151C7 for ; Tue, 29 Jun 1999 17:10:39 -0700 (PDT) (envelope-from wes@softweyr.com) Received: from mailhub.xylan.com by xylan.com (8.8.7/SMI-SVR4 (xylan-mgw 2.2 [OUT])) id RAA14507; Tue, 29 Jun 1999 17:10:15 -0700 (PDT) Received: from omni.xylan.com by mailhub.xylan.com (SMI-8.6/SMI-SVR4 (mailhub 2.1 [HUB])) id RAA03493; Tue, 29 Jun 1999 17:10:14 -0700 Received: from softweyr.com (dyn2.utah.xylan.com) by omni.xylan.com (4.1/SMI-4.1 (xylan engr [SPOOL])) id AA17397; Tue, 29 Jun 99 17:10:13 PDT Message-Id: <37796062.63879A32@softweyr.com> Date: Tue, 29 Jun 1999 18:10:10 -0600 From: Wes Peters Organization: Softweyr LLC X-Mailer: Mozilla 4.5 [en] (X11; U; FreeBSD 3.1-RELEASE i386) X-Accept-Language: en Mime-Version: 1.0 To: Kevin Bracey Cc: freebsd-net@FreeBSD.ORG Subject: Re: Old IP addresses hanging around in routes References: <4cf1d91949%kbracey@kbracey.acorn.co.uk> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Kevin Bracey wrote: > > In message > Julian Elischer wrote: > > > you have a point and I admit that I can't remember exactly what I do in > > this case. what about: > > > > ifconfig eh0 10.0.4.1 > > route add default 10.0.0.1 > > ifconfig eh0 down delete > > > > now what about the default route? > > > > Still through 10.0.0.1, in the absence of any other information. If the > interface comes back up, it will still be there. When we come to use the > route with the interface down, we will find that we can't actually get to > 10.0.0.1 so will have to back out. How this would be implemented is less > clear. > > What did 4.3BSD do in this case? 4.2BSD retained a pointer in the routing table to an ifnet structure that was no longer there. Ugh. I haven't looked at the 4.3 code, but this problem gets really ugly in the face of the example given above. You CANNOT keep the route, because the route has to refer to either an interface or an address, and if the address or interface doesn't exist anymore, the route cannot continue to exist. The moral of the story is to use a routing daemon. The other moral of the story is that routing daemons are evil, and difficult to configure properly. ;^) -- "Where am I, and what am I doing in this handbasket?" Wes Peters Softweyr LLC http://www.softweyr.com/~softweyr wes@softweyr.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message