[c-nsp] Object tracking

[Gary Roberton]

This one could be interesting...

I have a tunnel interface that I only want to be up when the ethernet
interface on the router is up.  I don't want to relate the tunnel to the
address of the ethernet, I need these to be separate.

So, does anyone know if I can shut the interface if the status of the object
changes?  If you have any example code that would be great...

Thanks

Gary