Multiple roots in MST
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10-30-2012 04:50 AM - edited 03-07-2019 09:45 AM
Hi All,
I am running 3 MST instances running on (including MST0) wherein i have defined SW1 as root for the MST0 & 1 while SW2 root for MST2. Both switches are interconnected. These switches also connect to the access switches. The issue is all switches (including SW1, SW2 and access switches) in the network are acting as spanning-tree root except for the MST0. MST0 is showing the right configured root.
According to my understanding the spanning tree should have one declared root. Need your help in correcting my understanding. Note the network is running fine.
BR..
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10-30-2012 08:12 AM
Hi,
Have you changed the priority on each switch?
spanning-tree mst 1 priority 8192
spanning-tree mst 2 priority 8192
HTH
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11-01-2012 04:02 AM
Hi Reza,
I have changed the priorities on the switches. What i found is that the switches are seeing the other switch in different MST region and the ports towards the confiugred root are in master forward state.
BR

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11-01-2012 05:05 AM
Hello,
Your instance mappings must match. Instance one on switch two has VLAN 899. Switch one has VLAN 889.
Regards,
Ryan
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11-04-2012 12:08 AM
Yes that i figured out but even after the changes it is not working.
BR

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11-04-2012 04:48 AM
Hello,
Could you please repost your configuration?
Ryan
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09-28-2024 11:06 PM
I think the previous rapid-pvst is conflicting with mst.
Try to remove rapid-pvst configuration and then activate mst
no spanning-tree mode mst
no spanning-tree mode rapid-pvst.
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09-28-2024 11:09 PM - edited 09-28-2024 11:10 PM
Also, remove rpvst root priority command if exist in running configuration
