PLANET ISW-1022MPT - Manual (Page 95)

User’s Manual of ISW-1022M Series and ISW-1033MT
95
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
Figure 5-39 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
Figure 5-40 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