[quagga-dev 4127] Re: Inconsistent "inactive" route in OSPF
mf at 14v.de
Mon May 8 17:29:52 BST 2006
(Sorry, hit "Send" to early...)
Paul Jakma wrote:
> Why is this other routing protocol installing routes for on-link
> addresses? Why is this not a bug in this /other/ routing protocol?
> Surely it should maintain a list of connected addresses and avoid
> installing obviously useless routes like the above?
Hello, such routes are not entirely useless, as they may be used for
redistribution. We had the same problem during migration of a network from
one location to another. During the migration, both locations were
distributing the same network route, and both locations were bridged
togehter over WAN. The bridging link was rather slow, so we wanted routing
from outside locations to use the correct link and avoid the bridging.
Therefore, both gateways maintained additional host routes to the hosts
they could reach locally without the bridge and redistributed them.
Worked fine for hosts, but not for OSPF routers :-)
Our workaround was this:
* add a link route for the OSPF router id (which is not from the
directly connected network):
ip route add <routerid> dev ethX
* manually add the OSPF routes (which were not changing much)
as gateway-routes to the <routerid>
ip route add <net> via <routerid>
IIRC, then the route to the <routerid> was considered "inactive", but the
<net> routes were accepted. Possibly this workaround was only possible
because the other OSPF routers were also running Linux and responded to ARP
request to any of their ip addresses
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