[FROG] Filtering kernel routes import

[Donald Sharp]

Specify a very very high metric for the default kernel route then and your
bgp default route will win:

http://docs.frrouting.org/en/latest/zebra.html#administrative-distance
https://www.kernel.org/doc/Documentation/networking/vrf.txt

Specifically if you set the kernel metric to say 4278198272 -> FRR will
interpret this as a Admin distance of 255 and a metric of 8192.  And your
BGP route will win.

donald


On Fri, Apr 9, 2021 at 7:17 AM Tim Weippert <weiti+frog at weiti.org> wrote:

> Hi donald,
>
> thanks for the answer.
>
> I had lab systems which get a default route via vagrant but frr
> shouldn't use them as the systems had some bgp peerings where i
> simulate an BGP Internet Peering environment.
>
> I solved my issue with the use of an vrf, but badly i can't use bgp
> flowspec within the vrf so this test cases aren't usable now (it is not
> really an
> issue ...).
>
> So expecially i would like to remove the kernel default route as within
> my simulation is a bgp generated default.
>
> hope this sounds reasonable.
>
> regards,
> tim
>
> On Fri, Apr 09, 2021 at 06:54:42AM -0400, Donald Sharp wrote:
> > No there isn't a way, because FRR really needs to know about routes in
> the
> > kernel so proper routing decisions can be made.  What are you really
> trying
> > to do here?
> >
> > donald
> >
> > On Fri, Apr 9, 2021 at 6:33 AM Tim Weippert <weiti+frog at weiti.org>
> wrote:
> >
> > > Hi,
> > >
> > > i'm trying to filter a kernel default route from beeing
> > > imported into frr/zebra.
> > >
> > > I tried with a prefix-list/route-map bound to ip procotol kernel#
> > > but it seems it get only used on export routes to the kernel, not
> > > import routes from the kernel.
> > >
> > > Is there a easy way to filter kernel route imports into frr/zebra?
> > >
> > > regards,
> > > tim
> > >
> > > --
> > > Tim Weippert
> > > http://weiti.org - weiti at weiti.org
> > > GPG Fingerprint - E704 7303 6FF0 8393 ADB1  398E 67F2 94AE 5995 7DD8
> > >
> > > _______________________________________________
> > > frog mailing list
> > > frog at lists.frrouting.org
> > > https://lists.frrouting.org/listinfo/frog
> > >
>
> > _______________________________________________
> > frog mailing list
> > frog at lists.frrouting.org
> > https://lists.frrouting.org/listinfo/frog
>
>
> --
> Tim Weippert
> http://weiti.org - weiti at weiti.org
> GPG Fingerprint - E704 7303 6FF0 8393 ADB1  398E 67F2 94AE 5995 7DD8
>
> _______________________________________________
> frog mailing list
> frog at lists.frrouting.org
> https://lists.frrouting.org/listinfo/frog
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.frrouting.org/pipermail/frog/attachments/20210409/3d8eda9a/attachment.htm>