Alaxala AX2200S Series Configuration Manual page 249

In link-not-down mode, sending from standby links (standby ports) stops, but the
status of the standby links (standby ports) does not change to link-down. Because
the standby links are in the link-up status, monitoring of faults can also be performed
for these standby ports. Note that in this mode, standby ports do not send data, but
can receive data. A device that does not support the standby link functionality does
not detect the link-down status on the partner device, and can continue sending to
the partner device. In link-not-down mode, connecting to the device is possible.
In link-down mode, if there is only one active port in a channel group and a fault occurs on
that port, the channel group is temporarily shut down when the faulty port is replaced with a
standby port. In link-not-down mode, the standby port replaces the faulty port without the
channel group shutting down.
The status in which only one port is active in a channel group arises in either of the
following cases:

The maximum number of active ports is set to 1 by using the
configuration command.

Only one port has the maximum speed, and the other ports have lower speed.
(4) Notes on using link-down mode
If Fastethernet ports and Gigabitethernet ports are mixed in the same channel group, and
Gigabitethernet ports are used as operating ports, use the
configuration command to set the higher priority to the Gigabitethernet ports. (A smaller
port priority value indicates a higher priority.)
14 Link Aggregation
max-active-port
lacp port-priority
227