User guide

Rapid Spanning Tree Protocol
ExtremeWare 7.2e Installation and User Guide 205
Suppose we have a network, as shown in Figure 33, with six bridges (bridge A through bridge F) where
the following is true:
• Bridge A is the root bridge
• Bridge D contains an alternate port in the blocking state
• All other ports in the network are in the forwarding state
Figure 33: Initial network configuration
The preceding steps describe how the network reconverges.
1 If the link between bridge A and bridge F goes down, bridge F detects the root port is down. At this
point, bridge F:
• Immediately deletes that port from the STP
• Performs a configuration update
After the configuration update, bridge F:
• Considers itself the new root bridge
• Sends a BPDU message on its designated port to bridge E
Figure 34: Down link detected
Designated
port
Root
port
EW_103
a
A
A , 0
B
A , 1
C
A , 2
F
A , 1
E
A , 2
D
A , 3
Blocked
port
EW_103
b
B
A , 1
C
A , 2
E
A , 2
D
A , 3
BPDU
Down
link
A
A , 0
F
F , 0
Designated
port
Root
port