BIRD trying to reinsert existing kernel routes, netlink issue?

[Sasha Romijn]

Hello,

Yes, my reading of the docs was also that importing kernel routes is not needed, there are no external routes beyond one default route.
(I did try out “import all” on the kernel protocol to be sure, no change).

There is no export filter on the kernel, it’s just “export all”.

The log sample I shared is really all that’s included in the log, repeated every kernel scan (other than some messages about unexpected BGP connections from peers - because I’ve trimmed the configuration on my end to the simplest possible for now). No other warnings or other pointers of any kind in the logs.

Sasha

> On 2 Aug 2020, at 20:48, Maria Matějka <maria.matejka at nic.cz> wrote:
> 
> Hello!
> BIRD reads the routes from kernel anyway, the import clause applies only on learned external routes. Do you have any export filter on that kernel protocol? Don't you have any suspicious warnings in log?
> Maria
> 
> On August 2, 2020 7:08:11 PM GMT+02:00, Alarig Le Lay <alarig at swordarmor.fr> wrote:
> Hi Sasha,
> 
> On Sun 02 Aug 2020 17:36:13 GMT, Sasha Romijn wrote:
> protocol kernel {
>     scan time 20;
>     ipv4 {
>         export all;
>         import none;
>     };
> }
> 
> I think that the issue is there, you’re not importing routes from the
> kernel, so bird doesn’t know that they exist, but you export all routes
> to it. So it ends up by resending an already existing route.
> 
> And for example, on my of my routers :
> bird> show route all 80.213.72.0/22
> Table master4:
> 80.213.72.0/22       unicast [direct1 2020-07-24] * (240)
> 	dev enp2s0
> 	Type: device univ
>                      unicast [kernel_grt_ipv4 2020-07-24] (10)
> 	dev enp2s0
> 	Type: inherit univ
> 	Kernel.source: 16
> 	Kernel.metric: 3
> 	Kernel.prefsrc: 80.213.74.176
> 	Kernel.scope: 253
> 
> This route is learned from both direct1 and kernel_grt_ipv4, so it would
> be re-sent to the kernel if I remove the "import all".
> 
> Regards,
> 
> -- 
> Sent from my Android device with K-9 Mail. Please excuse my brevity.

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