Configuring RSTP
Cisco Catalyst switches support three types of spanning-tree protocols: PVST+, PVRST+,
and MSTP.
?– PVST+: Based on the 802.1D standard, this includes Cisco proprietary extensions,
such as BackboneFast, UplinkFast, and PortFast, which improve STP convergence
time.
?– PVRST+: Based on the 802.1w standard, this has a faster convergence than 802.1D.
?– MSTP (802.1s): Combines the best aspects of PVST+ and the IEEE standards.
To implement PVRST+, perform these steps:
Step 1 Enable PVRST+.
Step 2 Designate and con?¬?gure a switch to be the root bridge.
Step 3 Designate and con?¬?gure a switch to be the secondary (backup) root
bridge.
Step 4 Verify the con?¬?guration.
Table 2-13 describes the commands that you use to enable and verify PVRST+.
Table 2-13 PVRST+ Commands
Command Description
SwitchX(con?¬?g)#spanning-tree mode
rapid-pvst
Sets spanning-tree mode to PVRST+
SwitchX#show spanning-tree vlan
vlan-number [detail]
Shows spanning-tree information that is VLANbased
rather than instance-based
SwitchX#debug spanning-tree pvst+ Debugs PVST+ events
SwitchX#debug spanning-tree switch
state
Debugs port state changes
Note: Like all debug commands, this command
can affect network performance.
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