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Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 7 Configuring Spanning Tree
Configuring MISTP-PVST+ or MISTP on the Switch
Follow these guidelines when mapping VLANs to an MISTP instance:
•
You can map only Ethernet VLANs to MISTP instances.
•
At least one VLAN in the instance must have an active port in order for MISTP-PVST+ or MISTP
to be active.
•
You can map as many Ethernet VLANs as you wish to an MISTP instance.
•
You cannot map a VLAN to more than one MISTP instance.
Note
To use VLANs 1025–4094, you must enable MAC address reduction. See the
“Creating Extended-Range
VLANs” section on page 11-7
in
Chapter 11, “Configuring VLANs”
for details on using extended-range
VLANs.
To map a VLAN to an MISTP instance, perform this task in privileged mode:
This example shows how to map a VLAN to MISTP instance 1 and verify the mapping:
Console> (enable)
set vlan 6 mistp-instance 1
Vlan 6 configuration successful
Console> (enable)
show spantree mist-instance 1
Instance 1
Spanning tree mode MISTP-PVST+
Spanning tree type ieee
Spanning tree instance enabled
Designated Root 00-d0-00-4c-18-00
Designated Root Priority 49153 (root priority: 49152, sys ID ext: 1)
Designated Root Cost 0
Designated Root Port none
VLANs mapped: 6
Root Max Age 20 sec Hello Time 2 sec Forward Delay 15 sec
Bridge ID MAC ADDR 00-d0-00-4c-18-00
Bridge ID Priority 49153 (bridge priority: 49152, sys ID ext: 1)
VLANs mapped: 6
Bridge Max Age 20 sec Hello Time 2 sec Forward Delay 15 sec
Port Inst Port-State Cost Prio Portfast Channel_id
------------------------ ---- ------------- --------- ---- -------- ----------
2/12 1 forwarding 22222222 40 disabled 0
Determining MISTP Instances—VLAN Mapping Conflicts
A VLAN can only be mapped to one MISTP instance. If you attempt to map a VLAN to more than one
instance, all of its ports are set to blocking mode. You can use the
show spantree conflicts
command to
determine to which MISTP instances you have attempted to map the VLAN.
This command prints a list of the MISTP instances that are associated with the VLAN, the MAC
addresses of the root switches that are sending the BPDUs containing the VLAN mapping information,
and the timers that are associated with the mapping of a VLAN to an MISTP instance. When only one
Task
Command
Step 1
Map a VLAN to an MISTP instance.
set vlan
vlan
mistp-instance
instance
Step 2
Verify the VLAN is mapped.
show spantree mistp-instance
[
instance
] [
active
]
mod/port
