Spanning Tree Commands 553
spanning-tree mode
Use the spanning-tree mode command in Global Configuration mode to
configure the spanning-tree protocol. To return to the default configuration,
use the no form of this command.
Syntax
spanning-tree mode {stp | rstp |mstp}
no spanning-tree mode
•
stp
— Spanning Tree Protocol (STP) is enabled.
•
rstp
— Rapid Spanning Tree Protocol (RSTP) is enabled.
•
mstp
— Multiple Spanning Tree Protocol (MSTP) is enabled.
Default Configuration
Rapid Spanning Tree Protocol (RSTP) is supported.
Command Mode
Global Configuration mode
User Guidelines
In RSTP mode the switch would use STP when the neighbor switch is using
STP. In MSTP mode the switch would use RSTP when the neighbor switch is
using RSTP and would use STP when the neighbor switch is using STP.
Example
The following example configures the spanning-tree protocol to MSTP.
console(config)#spanning-tree mode mstp
spanning-tree mst 0 external-cost
Use the spanning-tree mst 0 external-cost command to set the external cost
for the common spanning tree. The external cost is used by the switch when
negotiating spanning tree topology outside the region.
Since by default each switch is in its own region, the external cost is considered in
determining the spanning tree in the network.
