Solved

Switch is not in MST mode

Posted on 2014-11-24
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Last Modified: 2014-11-24
I have 4 switches configured with MST, same region name , same instances and vlans. However when I run  Show Spanning-Tree mst 1 , it dispswlays:
% Switch is not in mst mode


SW1#sh running-config | sect spanning
spanning-tree mode pvst
spanning-tree extend system-id
spanning-tree mst configuration
 name OUR-REGION
 instance 1 vlan 55-66
 instance 2 vlan 77-88
===============================
SW2#sh running-config | sect spanning
spanning-tree mode pvst
spanning-tree extend system-id
spanning-tree mst configuration
 name OUR-REGION
 instance 1 vlan 55-66
 instance 2 vlan 77-88
===============================
SW3#sh running-config | sect spanning
spanning-tree mode pvst
spanning-tree extend system-id
spanning-tree mst configuration
 name OUR-REGION
 instance 1 vlan 55-66
 instance 2 vlan 77-88
================================


SW4#sh running-config | section  spanning-tree
spanning-tree mode pvst
spanning-tree extend system-id
spanning-tree mst configuration
 name OUR-REGION
 instance 1 vlan 55-66
 instance 2 vlan 77-88
==========================
SW4#show sp
SW4#show spanning-tree mst 1
% Switch is not in mst mode
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Question by:jskfan
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3 Comments
 
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Accepted Solution

by:
benhanson earned 500 total points
ID: 40462842
You are configured with pvst, not mst, so you should just do 'show spanning-tree' to see your status.  If you wanted to switch to mst on all switches, you would do 'spanning-tree mode mst' on each of them, but I wouldn't do so unless you have a specific reason.  I would however switch to rpvst on each of them, running 'spanning-tree mode rapid-pvst' on each switch.  You will need to do this during a maintenance window as switching spanning tree modes will trigger a learn cycle if you don't already have all your ports set with portfast.  Rapid-pvst has quicker convergence than pvst, so certain spanning-tree operations can happen significantly faster with rpvst.
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Author Comment

by:jskfan
ID: 40462998
You are correct!! That's what I typed on all switches:

spanning-tree mst configuration  
name OUR-REGION
instance 1 vlan 55-66
instance 2 vlan 77-88

I should have enter MST mode first:
spanning-tree mode mst
spanning-tree mst configuration  
name OUR-REGION
instance 1 vlan 55-66
instance 2 vlan 77-88
0
 

Author Closing Comment

by:jskfan
ID: 40463000
Thank you !!
0

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