Layer 2 Switching Commands 768Configuration of the bridge priority is given preference over configuration ofthe root primary or root secondary configuration, which is given preferenceover the configuration of DirectLink Rapid Convergence.RSTP-PV embeds support for IRC and DRC. There is no provision to enableor disable these features in RSTP-PV configured switches.DRC is most useful for enterprise wiring-closet topologies with a limitednumber of VLANs. Do not enable DRC on backbone or distribution layerswitches as DRC is not capable of completing the reconfiguration of largenetworks within the max age time.Exampleconsole(config)#spanning-tree uplinkfastspanning-tree vlanUse the spanning-tree vlan command to enable per VLAN spanning tree on aVLAN. Use the no form of the command to remove the VLAN as a separatespanning tree instance.Syntaxspanning-tree vlan {vlan-list}no spanning-tree vlan {vlan-list}• vlan-list–A single VLAN ID or a list of VLAN IDs in comma delineated orrange format with no embedded blanks. Range 1-4093.Default ConfigurationBy default, each configured VLAN is automatically associated with a perVLAN spanning tree instance. If more than eight VLANs are configured, theexcess VLANs do not participate in per VLAN spanning tree.To change the allocation of spanning-tree instances to VLANs, use the nospanning-tree vlan command to disassociate a VLAN from a per VLANspanning-tree instance and use the spanning-tree vlan command to associatethe spanning-tree instance with the desired VLAN.Command ModesGlobal Configuration mode
