Owner's Manual

556 | Chapter 18. STP
NETGEAR 8800 User Manual
Figure 47. Communicating Port Status to Neighbors
6. To complete the topology change (as shown in Figure 48):
• Bridge D moves the port that received the “agree” message into the forwarding state.
• Bridge F confirms that its receiving port (the port that received the “propose”
message) is the root port, and immediately replies with an “agree” message to bridge
E to unblock the proposing port.
Figure 48. Completing the Topology Change
Figure 49 displays the new topology.
Figure 49. Final Network Configuration
Compatibility With STP (802.1D)
RSTP interoperates with legacy STP protocols; however, the rapid convergence benefits are
lost when interacting with legacy STP bridges.
Each RSTP bridge contains a port protocol migration state machine to ensure that the ports
in the STPD operate in the correct, configured mode. The state machine is a protocol entity
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
EX_055g
B
A , 1
C
A , 2
E
A , 4
D
A , 3
A
A , 0
F
A , 5
Designated
port
Root
port
EX_055h
B
A , 1
C
A , 2
E
A , 4
D
A , 3
A
A , 0
F
A , 5
Designated
port
Root
port