[LARTC] Possible kernel bug with routes

[Ard van Breemen]

On Mon, Mar 27, 2006 at 11:56:52AM +0200, Sven Anders wrote:
<snipped a lot>
> > ip route add 10.100.0.0/24 dev eth0 proto kernel scope link
> RTNETLINK answers: File exists

s/add/append/

> I thought they are different!?!
> Is here any difference I did not see?
> If they are not different, why does the kernel not recognize it
> (see above) and avoid the duplicate entry?

add prevents duplicates, append just adds.

> Another question:
> 
>  Why can't I set a route on an interface that is down?

That's by some design. Use patches from linuxvirtualserver.org if
you want them to exist.

>  I can set an address, so why not a route?

You don't set an address... The address exists only at the moment
the interface comes up. Before that you don't have the address
(active in your ip stack)

>  I there a reason for that?
>  As far as I understand routing should be handled independed from
>  the addresses...
Jups

> Example:
> > ip link set down dev eth0
> > ip addr add 10.100.0.1/24 dev eth0
> > ip route add 10.100.0.0/24 dev eth0  proto kernel  scope link
> RTNETLINK answers: Network is down

The ip is not there yet.
ip link set up dev eth0           # Activate interfaces
ip a add 127.0.0.1/32 dev eth0    # Bind interface to ipv4 stack
ip a add 10.100.0.1/32 dev lo     # We need a public ip on our ip stack
# Add the route to the interface with sane src ip.
ip route add 10.100.0.0/24 dev eth0 src 10.100.0.1

> PPS: Why is ANYBODY still ignoring this e-mail for over 3 weeks?????

People are busy :-)