Planet FGSW-2620VM User Manual page 86

User's Manual of FGSW-Series
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 = 20,000) 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 = 200,000). 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.
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