Indicates the PRBS test action to be executed on the interface
and whether the test is currently running or not.
'start' -- start the PRBS test on the interface.
'stop' -- stop the PRBS test on the interface.
'errorReset' -- reset the object value of
ccdPrbsIfTestErrors to zero on the interface.
'running' -- the PRBS test is currently running on the
interface. This value is a read-only value
and can not be set on the interface.
'notRunning' -- the PRBS test is currently not running
on the interface. This value is a read-only
value and can not be set on the interface.