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Multiple Spanning Tree Protocol | 645
Enable Multiple Spanning Tree Globally
MSTP is not enabled by default. To enable MSTP:
Verify that MSTP is enabled using the
show config command from PROTOCOL MSTP mode, as shown in
Figure 29-2.
Figure 29-2. Verifying MSTP is Enabled
When you enable MSTP, all physical, VLAN, and port-channel interfaces that are enabled and in Layer 2
mode are automatically part of the MSTI 0.
• Within an MSTI, only one path from any bridge to any other bridge is enabled.
• Bridges block a redundant path by disabling one of the link ports.
Add and Remove Interfaces
• To add an interface to the MSTP topology, configure it for Layer 2 and add it to a VLAN. If you
previously disabled MSTP on the interface using the command
no spanning-tree 0, re-enable it using
the command
spanning-tree 0.
• Remove an interface from the MSTP topology using the command
no spanning-tree 0 command. See
also Removing an Interface from the Spanning Tree Group on page 1054 for BPDU Filtering behavior.
Create Multiple Spanning Tree Instances
A single MSTI provides no more benefit than RSTP. To take full advantage of MSTP you must create
multiple MSTIs and map VLANs to them.
Create an MSTI using the command
msti from PROTOCOL MSTP mode. Specify the keyword vlan
followed by the VLANs that you want to participate in the MSTI, as shown in Figure 29-3.
Step Task Command Syntax Command Mode
1 Enter PROTOCOL MSTP mode.
protocol spanning-tree mstp
CONFIGURATION
2 Enable MSTP.
no disable
PROTOCOL MSTP
FTOS(conf)#protocol spanning-tree mstp
FTOS(config-mstp)#show config
!
protocol spanning-tree mstp
no disable
FTOS#