Does it have differences about information between kernel and process?

[Takeshi Kodama]

Hi,all.

I'm running zebra-0.92a on linux kernel-2.4.18.
I have a question about kernel-routing process interface.

When I configure, I can select NETLINK or IOCTL 
as kernel-routing process interface.
I think IOCTL carries information in only process->kernel direction,
not in kernel->process direction.

I have a question.

I think when I can select IOCTL as kernel-process interface,
it have differences about information between kernel and routing process.
For example, when I change interface status by "ifconfig" command,
The information in kernel is updated. But in routing process not updated.
(because IOCTL is process->kernel direction interface)

Is it no matter about such a specification? 

Is IOCTL already obsolete ?
The time when kernel didn't have NETLINK method,
Would something bad happen?

Regards.
-----
Takeshi Kodama