Extreme Networks ExtremeWare 7.2e, Installation And User Manual

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Rapid Spanning Tree Protocol
ExtremeWare 7.2e Installation and User Guide 211
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 39: 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 40: Communicating port status to neighbors
EW_103e
B
A , 1
C
A , 2
E
E , 0
Propose BPDU
A
A , 0
F
E , 1
D
A , 3
Designated
port
Root
port
EW_103f
B
A , 1
C
A , 2
E
A , 4
Agree BPDU
A
A , 0
F
E , 1
D
A , 3
Designated
port
Root
port