Reference Guide

846 | Rapid Spanning Tree Protocol
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When you enable Rapid Spanning Tree, all physical and port-channel interfaces that are enabled and in
Layer 2 mode are automatically part of the RST topology.
• Only one path from any bridge to any other bridge is enabled.
• Bridges block a redundant path by disabling one of the link ports.
Figure 47-2. Rapid Spanning Tree Enabled Globally
View the interfaces participating in Rapid Spanning Tree using the show spanning-tree rstp command
from EXEC privilege mode. If a physical interface is part of a port channel, only the port channel is listed
in the command output.
Command example:
show spanning-tree rstp
FTOS#show spanning-tree rstp
Root Identifier has priority 32768, Address 0001.e801.cbb4
Root Bridge hello time 2, max age 20, forward delay 15, max hops 0
Bridge Identifier has priority 32768, Address 0001.e801.cbb4
Configured hello time 2, max age 20, forward delay 15, max hops 0
R1
R2
R3
1/3
3/1
3/2
3/4
3/3
1/4
1/1 1/2
2/1
2/2
2/3
2/4
Port 684 (GigabitEthernet 4/43) is alternate Discarding
Discarding
Port path cost 20000, Port priority 128, Port Identifier 128.684
Designated root has priority 32768, address 0001.e801.cbb4
Designated bridge has priority 32768, address 0001.e801.cbb4
Designated port id is 128.684, designated path cost 20000
Number of transitions to forwarding state 0
BPDU : sent 3, received 219
The port is not in the Edge port mode
root
Forwarding
Blocking