duplicate device routes on linux

[Ondrej Zajicek]

On Mon, Feb 20, 2023 at 02:47:39PM +0100, ico wrote:
> Hello all,
> 
> Here at $work we are using bird for OSPF at some 30 linux boxes. Works
> great. But there is a thing that confuses me:
> ...
> When I run bird with this configuration, it inserts another route:
> 
> # ip route
> 10.0.0.0/24 dev eth0 proto kernel scope link src 10.0.0.1
> 10.0.0.0/24 dev eth0 proto bird scope link metric 32
> 
> Is this expected/correct behaviour? Or should I somehow filter those device
> routes out? I want those device routes to be read by OSPF, of course, just
> not to output them back. What is the best way to get rid of them?

Hello.

It is expected behavior. OSPF protocol computes best routes for all
networks in the OSPF domain, that includes routes to directly attached
networks (which are usually the direct routes, although in principle OSPF
could find indirect route with lower metric even for directly attached
network). You can just ignore them.

> Another unrelated question: When I run bird, it logs this:
> 
> bird: KRT: Netlink strict checking failed, will scan all tables at once
> bird: Started
> 
> Should I do something about that failed strict check? Is it important or
> only some info message I shouldn't worry about?

That is just old version of Linux kernel. It should work ok even with
this warning.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."