kern/106722: [net] [patch] ifconfig may not connect an interface to known network

[Andre Oppermann]

Gleb Smirnoff wrote:
> 
> I was afraid that this would raise an argument on multipath routing. Let's
> temporary do not speak about multipath but just decide what is the correct
> way to remove conflicting routes when we are assigning an IP prefix to a
> local interface?

IMO when configuring a interface with an IP address and network it should
kick out previous host and/or network routes matching it.  Unless those
are from locally configured interfaces, then it should reject the new
attempt.

The current behavior is a big problem when running routing daemons like
OpenBGPD or OpenOSPFD.  If you add a second router to a subnet and that
router receives that subnet already via the routing protocol you can't
configure the interface.

For the routing daemon a RTM_CHANGE in the replacement case is fine.

-- 
Andre