Extreme Networks ExtremeWare XOS 10.1, Manual

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Rapid Spanning Tree Protocol
ExtremeWare XOS 10.1 Concepts Guide 157
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
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 20: Sending a propose message to confirm a port role
5 Upon receiving the proposal, bridge E:
• Performs a configuration update
• Changes its receiving port to a root port
The existing designated port enters the blocking state.
Bridge E then sends:
• A “propose” message to bridge F
• An “agree” message from its root port to bridge D
Figure 21: Communicating port status to neighbors
EX_055e
B
A , 1
C
A , 2
E
E , 0
Propose BPDU
A
A , 0
F
E , 1
D
A , 3
Designated
port
Root
port
EX_055f
B
A , 1
C
A , 2
E
A , 4
Agree BPDU
A
A , 0
F
E , 1
D
A , 3
Designated
port
Root
port