[quagga-dev 4128] Re: Inconsistent "inactive" route in OSPF

Matthias Ferdinand mf at 14v.de
Mon May 8 17:21:17 BST 2006


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
IIRC, then this route was considered "inactive", but OSPF routes were 
accepted correctly.

Best regards,
Matthias




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