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From: Claudio Jeker (cjekerdiehard.n-r-g.com)
Date: Fri Aug 24 2007 - 04:05:04 CDT
On Wed, Aug 22, 2007 at 05:13:30PM +0200, Toni Mueller wrote:
> I have routing problems with OSPF. For reasons I don't understand right
> now, routing does not get adapted in the right way.
> Given are some OSPF speakers in a network /24 and a few dumb(er) boxen
> which have subnets of said /24 behind them. There are static routes
> pointing from some of the OSPF speakers to the networks behind the dumb
> boxen, with these mentioned as the gateway. I have "redistribute
> static" in all ospfd.conf's. More often than not, the OSPF speakers
> announce those routes with themselves set as the destination, and
> sometimes even take away dynamic announcements from other OSPF
> speakers, and typically announce "foreign" networks (which are behind
> other routers) with themselves as the destination (in BGP speak: "set
> nexthop self"). Often, the routing table, as shown with "netstat -rnf
> inet", shows the correct route for packets destined for networks which
> the machine advetised itself (erronously) as the gateway, but packets
> then don't go out the same interface to the real gateway. In OSPF, or
> with "route get", the display can be really different and eg. not show
> any further hops to the destination. Such things happen every few days,
> randomly, and while the network is otherwise completely undisturbed
> (ie, nobody's configuring anything, and there are no other "outages",
> too). I'm replacing bogus dynamic routes with static routes, working
> towards the abolishment of OSPF, but this is quite undesirable for
> other reasons.
> Any ideas about how to debug (and solve) this are most welcome!
> All relevant are OpenBSD 4.1/i386 -stable, as of May 24th, and a Cisco.
All redistributed networks are originated with a nexthop of the ospf
router. That is how it works for the moment and changing that is not
simple as you need to know if the nexthop you intend to use is reachable
by the other ospf routers. Make sure you only announce static routes that
are behind the router that redistributes them.