The status of an interface participating in Smart
link operation.
uninitialized (1) - A value of 'uninitialized'
indicates that, the interface is not configured.
active(2) - A value of 'active' indicates that,
the interface is actively forwarding traffic.
standby(3) - A value of 'standby' indicates that,
the interface is ready to forward traffic if
the active interface goes down.
down(4) - A value of 'down' indicates that,
the interface is physically down.