Extreme Networks ExtremeWare 7.2e, Installation And User Manual

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210 ExtremeWare 7.2e Installation and User Guide
Spanning Tree Protocol (STP)
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
After the configuration update, bridge E:
• Regards itself as the new root bridge
•
Sends BPDU messages on both of its root ports to bridges F and D, respectively
Figure 37: New root bridge selected
3 When bridge F receives the superior BPDU and configuration update from bridge E, bridge F:
• Decides that the receiving port is the root port
• Determines that bridge E is the root bridge.
Figure 38: Communicating new root bridge status to neighbors
EW_103c
B
A , 1
C
A , 2
E
E , 0
D
A , 3
BPDU
A
A , 0
F
F , 0
Designated
port
Root
port
EW_103d
B
A , 1
C
A , 2
E
E , 0
D
A , 3
A
A , 0
F
E , 1
Designated
port
Root
port