[FROG] Any way to force a local route weight to 0 ?

Donald Sharp donaldsharp72 at gmail.com
Tue Sep 21 11:43:36 UTC 2021


Install the local routes into the kernel with a very high metric.

http://docs.frrouting.org/en/latest/zebra.html#administrative-distance

`Zebra does treat Kernel routes as special case for the purposes of Admin
Distance. Upon learning about a route that is not originated by FRR we read
the metric value as a uint32_t. The top byte of the value is interpreted as
the Administrative Distance and the low three bytes are read in as the
metric. This special case is to facilitate VRF default routes.`

So create the local routes with a high value of say 4278198272. would cause
FRR to read the local route with a admin distance of 255 and a metric of
8192.  This allows FRR to treat the local routes as something that can be
overridden.

donald

On Tue, Sep 21, 2021 at 5:09 AM Thomas Martin <tmartincpp at gmail.com> wrote:

> Hello,
>
> I'm looking for a way to be able to force local routes to a weight of
> 0 (apart from modifying the source code).
> To be honest I don't think there is but maybe I missed something.
>
> My goal is to use a local route as a backup solution (if BGP is down
> for example), but to use it only if not sent through BGP.
>
> Thanks.
>
> Regards,
> Thomas
>
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>
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