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

[Bruce M. Simpson]

Anton Yuzhaninov wrote:
> Thursday, March 15, 2007, 7:30:54 PM, Andre Oppermann wrote:
>
> AO> IMO when configuring a interface with an IP address and network it should
> AO> kick out previous host and/or network routes matching it.  Unless those
> AO> are from locally configured interfaces, then it should reject the new
> AO> attempt.
>
> New route should replace existing one only if it have administrative
> distance (in cisco terms) smaller than AD for existing route.
>
> Preference of network from locally configured interface is only
> particular case of this general principle.
>   
We are obstructed by the current radix trie code only matching on 
destination and prefix. Adding 'administrative distance' to the FTE 
match is something which should seriously be considered. It is a 
stepping stone to equal cost multipath and would help in this situation.

It does however considerably change the semantics of the existing 
routing socket and its consumers would need to be updated to reflect 
that fact.

As I hinted at in my original response: it seems acceptable that 
ifconfig'ing an interface into the system should be able to clobber the 
overlapping routes in the meantime, but only until the architecture is 
fixed.

Regards,
BMS