Extreme Networks ExtremeWare XOS Guide Manual page 316

Spanning Tree Protocol
3 As shown in Figure 37, 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 37: Communicating new root bridge status to neighbors
A
A , 0
F
E , 1
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.
●
As shown in Figure 38, after the configuration update, bridge D:
Moves the alternate port to a designated port.
●
Sends a "propose" message to bridge E to solicit confirmation of its designated role and to
●
rapidly move the port into the designated state.
Figure 38: Sending a propose message to confirm a port role
A
A , 0
F
E , 1
ExtremeWare XOS 11.1 Concepts Guide
B C
A , 1 A , 2
Designated
port
E D
E , 0 A , 3
B C
A , 1 A , 2
Designated
port
E D
E , 0 A , 3
Propose BPDU
Root
port
EX_055d
Root
port
EX_055e
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