PLANET FGSW-2620VM - Manual (Page 53)

FGSW-2620VM / FGSW-2624SF User’s Manual
Priority setting, or influencing STP to choose a particular port to block using the Port Priority and Port Cost settings is,
however, relatively straight forward.
Bridge ID = 15
Port 3
Port 1 Port 2
A
Bridge ID = 20
Port 1
Port 2 Port 3
C
Bridge ID = 30
Port 1
Port 2 Port 3
B
LAN 1
LAN 2 LAN 3
Portcast = 19
Portcast = 19 Portcast = 19
Portcast = 4
Portcast = 4
Portcast = 19
Portcast = 4
Portcast = 4
Before Applying the STA Rules
In this example, only the default STP values are used.
Root Bridge
Port 3
Port 1 Port 2
A
Designated Bridge
Port 1
Port 2 Port 3
C
Port 1
Port 2 Port 3
B
LAN 1
LAN 2 LAN 3
Designated Port
Root Port Root Port
Designated Port
Blocked
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
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