Designing and Expanding the Network 2 - 31
Remote Failure Signaling
In any redundant link path, you can designate (that is, activate) only one
end as a redundant port pair (1-2 or 3-4). You must enable remote failure
signaling (RFS) if ports are connected to fiber with redundancy enabled at
the other end. If you enable ports at both ends as redundant, or if you do
not enable remote failure signaling at the distant end, improper operation
of the redundant switchover mechanism occurs (see Figure 2-11).
If the primary link experiences a local or remote fault, the backup link
activates and the primary ports disconnect (that is, they do not pass data to
and from the concentrator). Once the switchover to backup occurs, the
redundancy status indicators blink at the redundant module end. However,
primary port diagnostics continue to operate. If the fault clears, the primary
port is re-enabled.
Each redundancy status LED (located beneath the Activity LEDs):
❑ Is off - If you disable redundancy.
❑ Is on - If you enable redundancy and both ports are operational.
❑ Blinks - If a switchover occurs due to a link failure.
