Acer ALH-616ds User Manual page 23

Figure 3-2 Master and Slave hubs in stacking ALH-616ds.
Note: 1. To concern the convenience of the cross-wiring connection
between hubs, ALH-616ds provide 1 normal port (marked as "II)
and 1 cross-over port (marked as "X"). These 2 ports are wired
to each other by different wiring assignments.
2. The up-link port utilizes the first connection port with "X" sign.When
you connect to another hub by this uplink port, you
cannot simultaneously connect a PC to this port in which "II" sign
is marked . The reason being that if a PC is connected to it, the
physical signal in the cable will be corrupted.
• The built-in switches in slave hubs will be disabled automatically to avoid
data looping from multiple inter-connections of hubs, as shown in Figure
3-3.
Figure 3-3 Auto Data looping prevention in ALH-616ds.