The tVrrpOpInUseAdvInterval indicates the operational value
for the advertisement interval.
When the VRRP instance is operating as a master, the value
of tVrrpOpInUseAdvInterval is equivalent to the value of
vrrpOperationsAdvInterval.
When the VRRP instance is operating as a backup and the value of
tVrrpOpAdvIntervalInherit is set to 'true', the value of
tVrrpOpInUseAdvInterval equals the value in the advertisement
interval field of the VRRP Advertisement message received from the
current master.
When the VRRP instance is operating as a backup and the value of
tVrrpOpAdvIntervalInherit is set to 'false', the value of
tVrrpOpInUseAdvInterval is equivalent to the value of
vrrpOperationsAdvInterval.
Only the master router sends VRRP advertisements.