Hi Hans, Hi List, thank you for your clarification,
On Thu, Apr 16, 2015 at 06:27:30PM +0200, Hans van Kranenburg wrote: > Hi, > > On 16/04/15 16:43, Joel Brunenberg wrote: > >[...] > > > >Another idea was a static route for the containing /24 that would be > >exported via BGP while the /32 were filtered away. That however leaves > >the /24 route in place even if there are no more /32 routes left. If > >there is a way to change that, that would be great. > > Yes, I would suggest using a static blackhole route with the large aggregate > range for the BGP connection, and also export that to your local kernel > routing table to automatically drop traffic for all addresses that are > currently not in use. It seems I concentrated so much on the aspect of making the appearance of the route conditional that I missed the obvious point. What you say makes total sense. > Is there a special reason why you would want to have the /24 being removed > entirely if none of the other connections is up? I would like to retract the route in the case, no contributing routes are there so traffic is no longer attracted in that case. If that is not possible, a static blackhole route would be ok, too I guess. So its correct to assume that the following things would do? * in protocol static add a blackhole route for the aggregate network * export the aggregate route to the kernel * export the aggregate route to be BGP peers with next-hop self * NO NOT export the aggreage to the OSPF areas * Be happy and dance around the table I will have a try and see if it works. If there was a way to conditionally import a specific protocol or filter on the presence of specific prefixes in the RIB that would be awesome. Thank you so far, Joel /jbn -- Joel Brunenberg - Troisdorf PGP: 0xAD25981C
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