The AutoTracker extended ageing timer. This value indicates
how long the switch will remember the mac address and its
associated vlan information. The default value is 1200 secs.
This means that the mac information will be remembered for
(vBrdgTpATVLANAgeingTime - vBrdgTpAgingTime) seconds after the
mac is aged out. This value must be set to a value greater than
or equal to vBrdgTpAgingTime.