Bird and aggregates

[Stefan Jakob]

Hi Joel,

Announcing the /24 beside the /32s from each node isn't an option? Metric
could be lowered too.

Rgds, Stefan

Joel Brunenberg <ml at jjim.de> schrieb am Fr., 17. Apr. 2015 00:22:

> 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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