Unmapping Vlans From A Mistp Instance; Disabling Mistp-Pvst+ Or Mistp - Cisco WS-C4003 - Catalyst 4000 Chassis Switch Software Configuration Manual

Chapter 7 Configuring Spanning Tree
This command prints a list of the MISTP instances associated with the VLAN, the MAC addresses of
the root switches that are sending the BPDUs containing the VLAN mapping information, and the timers
associated with the mapping of a VLAN to a MISTP instance. When only one entry is printed or when
all the entries are associated to the same instance, the VLAN is mapped to that instance. If two or more
entries in the list are associated with different MISTP instances, the VLAN is in conflict.
To clear up the conflict, you must manually remove the incorrect mapping(s) from the root switch. The
remaining entry on the list becomes the official mapping.
To determine VLAN mapping conflicts, perform this task in privileged mode:
Task
Determine VLAN mapping conflicts.
This example shows there is an attempt to map VLAN 2 to MISTP instance 1 and to MISTP instance 3
on two different switches as seen from a third switch in the topology:
Console> (enable) show spantree conflicts 2
Inst MAC
---- ----------------- --------- ---------
1
3
The Delay timer shows the time in seconds remaining before the VLAN will join the instance. The field
displays inactive if the VLAN is already mapped to an instance (the timer has expired), or the VLAN is
in conflict between instances.
The Time Left timer shows the time in seconds left before the entry will expire and be removed from the
table. The timer is restarted every time an incoming BPDU confirms the mapping. Entries pertaining to
the root switch show inactive on the root switch itself.

Unmapping VLANs from a MISTP Instance

The keyword none is used to unmap the specified VLANs from the MISTP instances to which they are
currently mapped. When you unmap a VLAN from a MISTP instance, the resulting state of all the ports
of the VLAN (if the VLAN exists) is blocking.
To unmap a VLAN or all VLANs from a MISTP instance, perform this task in privileged mode:
Task
Unmap a VLAN from a MISTP instance.
This example shows how to unmap a VLAN from a MISTP instance:
Console> (enable) set vlan 6 mistp none
Vlan 6 configuration successful

Disabling MISTP-PVST+ or MISTP

When the switch is in MISTP mode, you disable spanning tree on an instance, not for the whole switch.
When you disable spanning tree on a MISTP instance, the instance still exists on the switch, all of the
VLANs mapped to it have all of their ports forwarding, and the instance BPDUs are flooded.
78-12647-02
Delay
00-30-a3-4a-0c-00 inactive
00-30-f1-e5-00-01 inactive
Software Configuration Guide—Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4
Command
show spantree conflicts vlan
Time left
20
10
Command
set vlan vlan mistp-instance none
Using MISTP-PVST+ or MISTP
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