How to know the ethernet LINK is down.

[Ben Greear <greearb@xxxxxxxxxxxxxxx>]

I'm working on adding link-aggregation to VLANs and I want
to be able to detect if a link is down (cable pulled, dead
NIC, dead remote NIC...)  Obviously, some errors will
not be detectable.

Right now, I'm planning on testing the ethernet netdevice->flags to see
if IFF_UP is set.  Will this do what I want?  Are there other things
I can check?

Thanks,
Ben

-- 
Ben Greear (greearb@xxxxxxxxxxxxxxx)  http://scry.wanfear.com/~greear 
Author of ScryMUD:  scry.wanfear.com 4444        (Released under GPL)
http://scry.wanfear.com