The operational status of the bonding port for this ifIndex.
If the state is NOT up, then it is down for the stated reason,
if known. If etsysVsbPortAdminStatus is down(2), then
etsysVsbPortOperStatus should be down(2). If etsysVsbPortAdminStatus
is changed to up(1) the etsysVsbPortOperStatus should change to
up(1) if the interface is ready to transmit and receive bonding
traffic. It should remain in the down(2) state if and only if
there is a fault that prevents it from going to the up(1) state.