Planet Networking & Communication WGS3-24000 User Manual page 133

B
Port 2
In this example, only the default STP values are used.
B
Port 2
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.
Portcast = 4
Portcast = 4
Port 1
Bridge ID = 30
Port 3
Portcast = 19
LAN 2
Before Applying the STA Rules
Designated Port
Root Port
Port 1
Port 3
LAN 2
After Applying the STA Rules
LAN 1
Portcast = 19
A
Port 3
Bridge ID = 15
Port 1
Port 2
Portcast = 4
Portcast = 4
Portcast = 19
LAN 1
A
Port 3
Root Bridge
Port 1
Port 2
Designated Port
Blocked
C
Port 1
Bridge ID = 20
Port 2
Port 3
Portcast = 19
LAN 3
Root Port
C
Port 1
Designated Bridge
Port 2
Port 3
LAN 3
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