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Multiple Instance Spanning-Tree Operation
Configuring MSTP
Configuring MST Instance Parameters
When you enable MSTP on the switch, a spanning tree instance is enabled 
automatically. The switch supports up to sixteen configurable MST instances 
for each VLAN group that you want to operate as an active topology within 
the region to which the switch belongs. When creating an instance, you must 
include a minimum of one VID. You can add more VIDs later if desired.
Command Page
[no] spanning-tree instance < 1..16 > vlan < vid> [ vid..vid ]
no spanning-tree instance < 1..16 >
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spanning-tree instance < 1..16 > priority < 0..15 > 3-37
Syntax: [no] spanning-tree instance < 1..16 > vlan < vid [ vid..vid ] >
no spanning-tree instance < 1..16 >
Configuring MSTP on the switch automatically configures the 
IST instance and places all statically and dynamically 
configured VLANs on the switch into the IST instance. This 
command creates a new MST instance (MSTI) and moves the 
VLANs you specify from the IST to the MSTI. 
You must map at least one VLAN to an MSTI when you create 
it. You cannot map a VLAN ID to more than one instance. You 
can create up to 16 MSTIs in a region. 
The no form of the command removes one or more VLANs from 
the specified MSTI. If no VLANs are specified, the no form of 
the command deletes the specified MSTI. 
When you remove a VLAN from an MSTI, the VLAN returns to 
the IST instance, where it can remain or be re-assigned to 
another MSTI configured in the region.
Note: Starting in software release 13.x.x, you can enter the 
spanning-tree instance vlan command before a static or 
dynamic VLAN is configured on the switch to preconfigure 
VLAN ID-to-MSTI mappings. No error message is displayed. 
Later, each newly configured VLAN that has already been 
associated with an MSTI is automatically assigned to the 
MSTI. 
This new default behavior differs from automatically 
including configured (static and dynamic) VLANs in the IST 
instance and requiring you to manually assign individual 
static VLANs to an MSTI.