Indicates whether Extended System ID feature
is operationaly enabled on the device or not.
If the value of this object is true(1), then
the accepted values for dot1dStpPriority
in BRIDGE-MIB should be multiples of 4096 plus
bridge instance ID, such as VlanIndex. Changing
this object value might cause the values of
dot1dBaseBridgeAddress and dot1dStpPriority
in BRIDGE-MIB to be changed also.