Another Netlink: File exists

[micah anderson]

Ondrej Zajicek <santiago at crfreenet.org> writes:

> On Mon, Oct 06, 2014 at 10:15:51AM -0400, micah wrote:
>> micah <micah at riseup.net> writes:
>> 
>> Some additional information, I do have a handful of static routes
>> defined:
>> 
>> protocol static static_bgp {
>>         import all;
>>         route 204.13.164.0/24 reject;
>>         route 198.252.153.0/24 reject;
>>         route 199.254.238.0/24 reject;
>> }
>> 
>> and these appear in bird as follows:
>> 
>> # birdc show route |grep '!'
>> 204.13.164.0/24    unreachable [static_bgp 2014-10-04] ! (200)
>> 198.252.153.0/24   unreachable [static_bgp 2014-10-04] ! (200)
>> 199.254.238.0/24   unreachable [static_bgp 2014-10-04] ! (200)
>> 
>> which I understand is bird trying to add a route to the kernel, but it
>> is already there.
>
> Yes, that is exactly the reason for having 'Netlink: File exists' error
> message.
>
> BIRD does not rewrite routes that are already in kernel table from other
> sources.
>
> If you need them in kernel regardless of BIRD, you can as a workaround
> learn these routes from kernel proto and set them higher preference
> (using 'preference') than ones from static proto. That would prevent
> static routes to be exported to the kernel.

How do I learn these from kernel proto? 

I've got the following, should I move those route lines I have in
protocol static up into protocol kernel and change the preference in
protocol kernel to be higher? Or do I leave them also in protocol
static, but also have them in protocol kernel, with the preference in
protocol kernel higher?

protocol kernel {
        learn;			# Learn all alien routes from the kernel
        preference 10000;
        scan time 15;		# Scan kernel routing table every 20 seconds
	import all;		# Default is import all
	export all;		# Default is export none
}

##########################################################################
## static routes
##########################################################################

protocol static static_bgp {
        # prefixes that are propagated to upstream. These prefixes are represented as 
        # unreachable routes, which seems strange but it does not matter for BGP and has 
        # a secondary advantage that packets for AS-local but unreachable destinations are 
        # rejected and not sent to the upstream.
        import all;
        preference 10000;
        route 204.13.164.0/24 reject;
        route 198.252.153.0/24 reject;
        route 199.254.238.0/24 reject;
}

Also - will the better rate filtering of log messages changes in 1.4.5
make this less of a problem?

thanks!
micah