Configuration manual

670 | Multiple Spanning Tree Protocol
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Flush MAC Addresses after a Topology Change
FTOS has an optimized MAC address flush mechanism for RSTP, MSTP, and PVST+ that flushes
addresses only when necessary, which allows for faster convergence during topology changes. However,
you may activate the flushing mechanism defined by 802.1Q-2003 using the command
tc-flush-standard,
which flushes MAC addresses upon every topology change notification. View the enable status of this
feature using the command
show running-config spanning-tree mstp from EXEC Privilege mode.
Displaying STP Guard Configuration
To verify the STP guard configured on MSTP interfaces, enter the show spanning-tree msti
[instance-number] guard
command. Refer to Chapter 53, “Spanning Tree Protocol,” on page 1063 for
information on how to configure and use the STP root guard, loop guard, and BPDU guard features.
Figure 30-9 shows an example for instance 5 in an MSTP network in which:
• Root guard is enabled on a port that is in a root-inconsistent state.
• Loop guard is enabled on a port that is in a forwarding state.
• BPDU guard is enabled on a port that is shut down.
Figure 30-9. Displaying STP Guard Configuration
Force10#show spanning-tree msti 5 guard
Interface
Name Instance Sts Guard type
--------- -------- --------- ----------
Gi 0/1 5 INCON(Root) Root
Gi 0/2 5 FWD Loop
Gi 0/3 5 EDS(shut) Bpdu