Extreme Networks ExtremeWare XOS Guide - Page 444

Spanning Tree Protocol
ExtremeWare XOS 11.3 Concepts Guide
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As shown in Figure 41, 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 41: New root bridge selected
3 As shown in Figure 42, 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 42: Communicating new root bridge status to neighbors
4 Bridge D believes that bridge A is the root bridge. When bridge D receives the BPDU from bridge E
on its alternate port, bridge D:
● Immediately begins the max age timer on its alternate port.
● Performs a configuration update.
EX_055c
B
A , 1
C
A , 2
E
E , 0
D
A , 3
BPDU
A
A , 0
F
F , 0
Designated
port
Root
port
EX_055d
B
A , 1
C
A , 2
E
E , 0
D
A , 3
A
A , 0
F
E , 1
Designated
port
Root
port