Cisco WS-C2948G-GE-TX Configuration Manual page 136

Using MISTP-PVST+ or MISTP
To determine VLAN mapping conflicts, perform this task in privileged mode:
Task
Determine VLAN mapping conflicts.
This example shows that 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 00-30-a3-4a-0c-00
3 00-30-f1-e5-00-01
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.
The following examples are with VTP version 3 enabled. The root switch is also the primary server for
the nonroot switch. The root switch is not the primary server for the switch in conflict, because that
switch has been partitioned.
This example is from the root switch:
Console> (enable) show spantree conflicts 1
No conflicts for vlan 1.
Inst MAC
---- ----------------- --------- ---------
1 00-05-31-40-64-00
Console> (enable)
This example is from the nonroot switch:
Console> (enable) show spantree conflicts 3
No conflicts for vlan 3.
Inst MAC
---- ----------------- --------- ---------
3 00-05-31-40-64-00
Console> (enable)
This example is from the switch in conflict (note that the switch is inactive):
Console> (enable) show spantree conflicts 6
Inst MAC
---- ----------------- --------- ---------
6 00-05-31-40-64-00
5 00-09-7b-62-b0-80
Console> (enable)
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2948G-GE-TX, and Catalyst 2980G Switches Software Configuration Guide—Release 8.2GLX
7-38
Command
show spantree conflicts vlan
Delay Time left
inactive 20
inactive 10
Delay Time left
inactive inactive
Delay Time left
inactive 19
Delay Time left
inactive 18
inactive inactive
Chapter 7 Configuring Spanning Tree
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