D-Link DES-3326 User Manual - page 62
DES-3326 Layer 3 Fast Ethernet Switch User’s Guide
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Switch Management and Operating Concepts
Figure 5-5. After Applying the STA Rules
The switch with the lowest Bridge ID (switch C) was elected the
root bridge, and the ports were selected to give a high port cost
between switches B and C. The two (optional) Gigabit ports
(default port cost = 4) on switch A are connected to one (optional)
Gigabit port on both switch B and C. The redundant link between
switch B and C is deliberately chosen as a 100 Mbps Fast Ethernet
link (default port cost = 19). Gigabit ports could be used, but the
port cost should be increased from the default to ensure that the
link between switch B and switch C is the blocked link.
Note also that the example network topology is intended to provide
redundancy to protect the network against a link or port failure –