The 'oper_status' attribute of a port in our DB has three potential values: 'up', 'down' and '2'.

Can reproduce on a T0 setup. Simply 'ifdown' a port that's part of the VLAN. Reading the database rapidly, you will see the 'oper_status' change from 'up' to 'down' and then quickly to '2', where it will stay.

Likewise, bringing the port back up using 'ifup', you will see the 'oper_status' change from '2' to 'down' and then to 'up'.