Extreme Networks ExtremeWare XOS Guide Manual page 315

The following 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 disables that port from the STP.
●
Performs a configuration update.
●
As shown in Figure 35, after the configuration update, bridge F:
Considers itself the new root bridge.
●
Sends a BPDU message on its designated port to bridge E.
●
Figure 35: Down link detected
A
A , 0
Down
F
F , 0
Designated
port
2 Bridge E believes that bridge A is the root bridge. When bridge E receives the BPDU on its root port
from bridge F, bridge E:
Determines that it received an inferior BPDU.
●
Immediately begins the max age timer on its root port.
●
Performs a configuration update.
●
As shown in Figure 36, after the configuration update, bridge E:
Regards itself as the new root bridge.
●
Sends BPDU messages on both of its designated ports to bridges F and D, respectively.
●
Figure 36: New root bridge selected
A
A , 0
F
F , 0
ExtremeWare XOS 11.1 Concepts Guide
B
A , 1
link
BPDU
E
A , 2
Root
port
B
A , 1
Designated
E
E , 0
C
A , 2
D
A , 3
C
A , 2
port
Root
port
D
A , 3
BPDU
Rapid Spanning Tree Protocol
EX_055b
EX_055c
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