link_watchdog - Atlantic777/mpudp Wiki
Monitor link status. There are at least 3 states for a link.
- Link is present in the OS, but down
- Link is present in the OS, and up
- Link is present, UP and running
This are possible transitions:
- up and running link disappears
- present link which was up becomes down
- present link disappears
- up and running link goes down
Assume all links present, up and running for now.