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 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.
4.6.2 Spanning Tree Configuration
The Spanning Tree Protocol (STP) operates on two levels: On the switch level, the settings are globally
implemented. On the port level, the settings are implemented on a. per user-defined Group of ports.
1. Spanning Tree Configuration
The “
Rapid Spanning Tree Bridge Configure”
table allows configuring the spanning tree parameters.
Rapid Spanning Tree Status:
The spanning tree function of the switch is default disabled.
This field enables to
turn on the spanning tree on the switch.
Force Protocol Version:
0 for IEEE 802.1D Spanning Tree, 2 for IEEE 802.1W Rapid Spanning Tree
Max Age:
(6 - 40 sec) the default setting is 20
Hello Time:
(1 - 10sec) the default setting is 2
Forward Delay:
(4 -30 sec) the default setting is 15
Bridge Priority:
(0 - 61440) the default setting is 32768
