periodic krt_scan when learning and import is not enabled

[Maria Matejka]

Hello!

BIRD checks that the routes in OS table are still there. If you delete 
any of them accidentally, BIRD reinstalls it as soon as possible.

Maria

On 9/17/21 7:59 AM, Senthil Kumar Nagappan wrote:
> Hi,
> 
> I assume when kernel protocol is configured with export all “protocol 
> kernel {ipv4 { export all;};}”, bird performs synchronization of bird's 
> routing tables with the OS kernel.
> 
> When the learn switch is disabled and no import is there, why bird is 
> doing a periodic krt_scan and sends netlink request to os kernel to get 
> the routes dump?
> 
> When learn switch is enabled, then non bird routes are learnt from os 
> kernel and added to bird’s routing table, then what's the use of import 
> command? Looks bit ambiguous.
> 
> Please correct me if my understanding is incorrect.
> 
> Debug all all enabled:
> 
> bird: krt_scan(time=2021-09-17 05:28:40.478)
> 
> bird: kernel1: Scanning routing table
> 
> bird: kernel1: 0.0.0.0/0: [alien] ignored
> 
> bird: kernel1: Pruning table master4
> 
> my bird config for kernel:
> 
> protocol kernel {
> 
> ipv4 { };
> 
> }
> 
> Or this happens with this config too
> 
> protocol kernel {
> 
> ipv4 { export all;};
> 
> }
> 
> 
> 
> Thanks and Regards,
> Senthil
>