Administrator Guide

Layer 2 Switching Commands 785
Configuration of the bridge priority is given preference over configuration of
the root primary or root secondary configuration, which is given preference
over the configuration of DirectLink Rapid Convergence.
RSTP-PV embeds support for IRC and DRC. There is no provision to enable
or disable these features in RSTP-PV configured switches.
DRC is most useful for enterprise wiring-closet topologies with a limited
number of VLANs. Do not enable DRC on backbone or distribution layer
switches as DRC is not capable of completing the reconfiguration of large
networks within the max age time.
Example
console(config)#spanning-tree uplinkfast
spanning-tree vlan
Use the spanning-tree vlan command to enable per VLAN spanning tree on a
VLAN. Use the no form of the command to remove the VLAN as a separate
spanning tree instance.
Syntax
spanning-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 or
range format with no embedded blanks. Range 1-4093.
Default Configuration
By default, each configured VLAN is automatically associated with a per
VLAN spanning tree instance. If more than eight VLANs are configured, the
excess VLANs do not participate in per VLAN spanning tree.
To change the allocation of spanning-tree instances to VLANs, use the no
spanning-tree vlan command to disassociate a VLAN from a per VLAN
spanning-tree instance and use the spanning-tree vlan command to associate
the spanning-tree instance with the desired VLAN.
Command Modes
Global Configuration mode
2CSNXXX_SWUM204.book Page 785 Monday, January 25, 2016 1:25 PM