Spanning Tree Issue

[dbronco]

I am working on connecting some upgraded circuits from our ISP and am having a hard time navigating the dual links that were ordered. I'm working with Catalyst 9300s running 17.5 and am trying to connect both links through my routers. They are dual 600 Mbps connections, I only need one running at a time as my bandwidth isn't that high but I'm open to suggestions on how to best do this. 

The issue is that every time I connect the second link, I receive the following error from my main site (Hub and spoke architecture).  

%SPANTREE-2-PVSTSIM_FAIL: Blocking designated port Te1/1/1: Inconsitent superior PVST BPDU received on VLAN 2241, claiming root 0:3c41.0eb4.3080

I've added a drawing and some of the configs that I hope are helpful. 

[MHM Cisco World]

ISP not pass BPDU between sites 

This make each SW claim it is root'

Do

Show spanning interface ×/×

Check the bpdu send/receive 

MHM

[dbronco]

Thanks for the response. I don't see any output for that interface, but I imagine that's because it's currently unplugged correct? 

9.1#sho spanning interface te1/1/1

Mst Instance Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
MST0 Desg FWD 20000 128.53 P2p
PSN-OHQS-1F13-CORE#sho spanning interface te1/1/3
no spanning tree info available for TenGigabitEthernet1/1/3

9.2#show spanning interface te 1/1/1

Mst Instance Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
MST0 Desg FWD 20000 128.53 P2p Bound(PVST)
MST1 Desg FWD 20000 128.53 P2p Bound(PVST)
MST2 Desg FWD 20000 128.53 P2p Bound(PVST)
MST3 Desg FWD 20000 128.53 P2p Bound(PVST)
MST4 Desg FWD 20000 128.53 P2p Bound(PVST)
MST5 Desg FWD 20000 128.53 P2p Bound(PVST)
PSN-OHQS-1F13-2-SW#show spanning interface te 1/1/8

Mst Instance Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
MST0 Root FWD 2000 128.60 P2p
MST1 Root FWD 2000 128.60 P2p
MST2 Root FWD 2000 128.60 P2p
MST3 Root FWD 2000 128.60 P2p
MST4 Root FWD 2000 128.60 P2p
MST5 Root FWD 2000 128.60 P2p
PSN-OHQS-1F13-2-SW#

26.1#show spanning interface te 1/1/1

Mst Instance Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
MST0 Desg FWD 20000 128.53 P2p Bound(PVST)
PSN-DD02-1E100-CORE#show spanning interface te 1/1/2

Mst Instance Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
MST0 Desg FWD 20000 128.54 P2p

[MHM Cisco World]

You run MST in one side and PVST in other side?

MHM

[dbronco]

No, but thank you for making me double check. I think I just found the issue. 

Config from 26.1 

spanning-tree mode mst
spanning-tree extend system-id
no spanning-tree vlan 301-1001,1006-4094
spanning-tree vlan 1,21-22,24,26,28-29,64-66 priority 0

Config from 9.1

spanning-tree mode mst
spanning-tree extend system-id
spanning-tree vlan 2-10,27,111,992-993,999,1325,1400 priority 4096

I imagine I need to delete the 'no spanning-tree vlan 301-1001,1006-4094' line in 26.1 correct? And then add VLAN 2241 and 2242 to the spanning-tree lines? 

[MHM Cisco World]

Ohh, good job 

You disable SPT in these two VLAN and this make issue, I think so.

So 

 no spanning-tree vlan 301-1001,1006-2240, 2243-4094
spanning-tree vlan 1,21-22,24,26,28-29,64-66,2241, 2242 priority 0

I think this better than remove command no spanning tree

MHM

[dbronco]

Thank you for that. I won't be able to try this until Monday but I will update once I do

[MHM Cisco World]

Friend you are so so welcome 

Goodluck in your task 

Have a nice weekend 

MHM

[dbronco]

Unfortunately this didn't work and I'm stilling getting the same error. I'm wondering if it has something to do with the MST settings. Would you be able to review these and see if you see something in it? 

26.1#sh spanning-tree mst configuration
Name [26.1_MST]
Revision 1 Instances configured 8

Instance Vlans mapped
-------- ---------------------------------------------------------------------
0 1-20,23,25,27,30-64,67-4094
1 21
2 22
3 65
4 24
5 28-29
6 26
7 66
-------------------------------------------------------------------------------
26.1#sh spanning-tree mst detail

##### MST0 vlans mapped: 1-20,23,25,27,30-64,67-4094
Bridge address d4ad.bd84.5d80 priority 4096 (4096 sysid 0)
Root this switch for the CIST
Operational hello time 2 , forward delay 15, max age 20, txholdcount 6
Configured hello time 2 , forward delay 15, max age 20, max hops 20

9.1#sh spanning-tree mst configuration
Name [MST_Switches]
Revision 1 Instances configured 6

Instance Vlans mapped
-------- ---------------------------------------------------------------------
0 1,5,7-8,10-4094
1 2
2 3
3 4
4 6
5 9
-------------------------------------------------------------------------------
9.1#sh spanning-tree mst detail

##### MST0 vlans mapped: 1,5,7-8,10-4094
Bridge address 3c41.0eb4.3080 priority 0 (0 sysid 0)
Root this switch for the CIST
Operational hello time 2 , forward delay 15, max age 20, txholdcount 6
Configured hello time 2 , forward delay 15, max age 20, max hops 20

[MHM Cisco World]

sorry I make you waiting to check some thing in lab

How two SW run MST and dont match same instance ?

MHM

[dbronco]

I'll admit that I don't know much about MST, this was a configuration setup by the guy previously. As I'm looking at this though, are you talking about MST 0 for both sides? 

26.1#sh spanning-tree mst configuration
Name [26.1_MST]

Instance Vlans mapped
-------- ---------------------------------------------------------------------
0 1-20,23,25,27,30-64,67-4094
1 21
2 22
3 65
4 24
5 28-29
6 26
7 66

9.1#sh spanning-tree mst configuration
Name [MST_Switches]

Instance Vlans mapped
-------- ---------------------------------------------------------------------
0 1,5,7-8,10-4094
1 2
2 3
3 4
4 6
5 9

It appears the previous engineer configured MST 0 for all the VLANs that were not being used on that site - are you saying these should match instead? Or at least include VLANs 2241 and 2242 for the two connections? 

[dbronco]

It appears that I have a problem very similar to what is discussed here https://community.cisco.com/t5/switching/problem-in-migration-from-pvst-to-mstp/td-p/2501943 

The difference being that the error in that article is "inferior BPDU" where mine is a "superior BPDU". I think the concept is the same though. Looking through my configs, I believe that the 9.1 device needs to have its priority change to 8192 (or higher) for this to work. 

26.1#show spanning-tree root

Root Hello Max Fwd
MST Instance Root ID Cost Time Age Dly Root Port
---------------- -------------------- --------- ----- --- --- ------------
MST0 4096 d4ad.bd84.5d80 0 2 20 15
MST1 1 d4ad.bd84.5d80 0 2 20 15
MST2 2 d4ad.bd84.5d80 0 2 20 15
MST3 3 d4ad.bd84.5d80 0 2 20 15
MST4 4 d4ad.bd84.5d80 0 2 20 15
MST5 5 d4ad.bd84.5d80 0 2 20 15
MST6 6 d4ad.bd84.5d80 0 2 20 15
MST7 7 d4ad.bd84.5d80 0 2 20 15

26.1 (snip from show run)

spanning-tree mode mst
spanning-tree extend system-id
no spanning-tree vlan 301-1001,1006-4094
spanning-tree vlan 1,21-22,24,26,28-29,64-66,2241-2242 priority 0
!
spanning-tree mst configuration
name Titan_MST
revision 1
instance 1 vlan 21
instance 2 vlan 22
instance 3 vlan 65
instance 4 vlan 24
instance 5 vlan 28-29
instance 6 vlan 26
instance 7 vlan 66
!
spanning-tree mst 0 priority 4096
spanning-tree mst 1-7 priority 0

9.1#show spanning-tree root

Root Hello Max Fwd
MST Instance Root ID Cost Time Age Dly Root Port
---------------- -------------------- --------- ----- --- --- ------------
MST0 0 3c41.0eb4.3080 0 2 20 15
MST1 1 3c41.0eb4.3080 0 2 20 15
MST2 2 3c41.0eb4.3080 0 2 20 15
MST3 3 3c41.0eb4.3080 0 2 20 15
MST4 4 3c41.0eb4.3080 0 2 20 15
MST5 5 3c41.0eb4.3080 0 2 20 15

9.1 (snip from show run)

spanning-tree mode mst
spanning-tree extend system-id
spanning-tree vlan 2-10,27,111,992-993,999,1325,1400 priority 4096
!
spanning-tree mst configuration
name MST_Switches
revision 1
instance 1 vlan 2
instance 2 vlan 3
instance 3 vlan 4
instance 4 vlan 6
instance 5 vlan 9
!
spanning-tree mst 0-5 priority 0

It appears that the previous engineer configured MST 0 for all the VLANs that were not being used. 

- Can I change only the priority for MST 0? 

- What impact can I expect when changing this? Will there be a convergence time for the spanning tree to rebuild? 

[MHM Cisco World]

First sorry I make you waiting my reply 

the issue not BPDU superior or inferior
the issue is MST is not match in both site

the bound(RSTP) or Bound(PVST) is the key for this issue

you mention the previous Engineer config MST like this, I dont know why , and you need to know why

the MST misconfig is lead to these log message and if I am correct in end it can lead to L2 Loop. 

so check with him.

Thanks a lot 

MHM

 

[dbronco]

No need to apologize, I appreciate all the help, conversation and education 

Unfortunately speaking with the previous engineer isn't an option so I'm trying to figure this out and make it right myself. 

Speaking with a tech from my ISP, he believes that it's my MST priority trying to take the root. Device 9.1 is set to priority 0 while 26.1 is set to 4096. 

26.1#sh spanning-tree mst configuration
Name [26.1_MST]
Revision 1 Instances configured 8

Instance Vlans mapped
-------- ---------------------------------------------------------------------
0 1-20,23,25,27,30-64,67-4094
1 21
2 22
3 65
4 24
5 28-29
6 26
7 66
-------------------------------------------------------------------------------
26.1#sh spanning-tree mst detail

##### MST0 vlans mapped: 1-20,23,25,27,30-64,67-4094
Bridge address d4ad.bd84.5d80 priority 4096 (4096 sysid 0)
Root this switch for the CIST
Operational hello time 2 , forward delay 15, max age 20, txholdcount 6
Configured hello time 2 , forward delay 15, max age 20, max hops 20

9.1#sh spanning-tree mst configuration
Name [MST_Switches]
Revision 1 Instances configured 6

Instance Vlans mapped
-------- ---------------------------------------------------------------------
0 1,5,7-8,10-4094
1 2
2 3
3 4
4 6
5 9
-------------------------------------------------------------------------------
9.1#sh spanning-tree mst detail

##### MST0 vlans mapped: 1,5,7-8,10-4094
Bridge address 3c41.0eb4.3080 priority 0 (0 sysid 0)
Root this switch for the CIST
Operational hello time 2 , forward delay 15, max age 20, txholdcount 6
Configured hello time 2 , forward delay 15, max age 20, max hops 20

The MST 0 instance on both sides include all the VLANs that are not being used. If I only change the MST 0 priority on 9.1 to 8192, would that not fix the problem? 

Current config 

26.1
spanning-tree mst 0 priority 4096
spanning-tree mst 1-7 priority 0

9.1
spanning-tree mst 0-5 priority 0

Proposed new config

9.1

spanning-tree mst 0 priority 8192
spanning-tree mst 1-5 priority 0