The value of vRtrIfDelayUpTimer indicates the time left before the
interface comes up when vRtrIfDelaySeconds is configured to a
non-zero value.
When the interface is down, this object will return the value -1.
It's value can be in the range 0 to vRtrIfDelaySeconds's value
if the interface is 'about to come up'.
If the interface is up, the value of vRtrIfDelayUpTimer will be 0.