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