D-Link DE-1824EI User Manual page 34

10BASE-T Stackable Hubs
Figure 4 -3 All Hubs Connected to Ethernet Backbone
Figure 4 -3 shows an unsegmented stack of hubs. All hubs in the stack are in
the same collision domain because they are connected together using the
daisy-chain ports and they have not been segmented.
Figure 4 -4 shows a stack divided into three separate collision domains.
Hubs 4 and 5 are isolated from Collision Domain 1 (hubs 1, 2, and 3) using
the hub segmentation capability, putting them into their own isolated
Collision Domains 2 and 3 respectively. A switch, bridge or router can be
used to connect the three collision domains so that traffic can pass between
them, yet keeping them isolated to reduce congestion on each segment.
Without an additional connection, none of the three Collision Domains will
be able to pass traffic across domains, however, using a pass-through cable to
cascade the domains would negate their usefulness as separate segments.
4-6 Building Hub Stacks