D-Link DE-1824EI User Manual page 35

Figure 4 -4 Three Separate Collision Domains
When a hub is segmented from the rest of the stack, the Segmented indicator
on the front panel display will light. For information about segmenting hubs
using the console interface, see Chapter 6 in this User's Guide.
information about segmenting hubs using the network management module
for the hub, see the management module's User's Guide.
NOTE:
Building Hub Stacks
Hub segmentation is controlled by the master
hub. While the hub is performing its Power-On
Self-Test (POST), all hubs in the stack will be
connected together in a single segment. When
the master hub completes its initialization, it will
restore any segmentation of the hubs.
Therefore, if you are using a switch or bridge to
join different segments, be sure to enable the
IEEE 803.1d Spanning Tree Protocol to
prevent temporary network loops.
10BASE-T Stackable Hubs
For
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