Ideal MSTP configuration for Cisco switches to interoperate with Meraki?

Nater
Comes here often

Ideal MSTP configuration for Cisco switches to interoperate with Meraki?

I'm trying to resolve an STP problem which has taken our whole network down the last two days, and I want to make sure I have the ideal MSTP configuration on our Catalyst 6509 for interoperating with all our switches, especially Meraki but also some legacy HP.

 

Initially I had this configuration on our core switch when I transitioned it from PVST to MSTP:

 

spanning-tree mode mst
spanning-tree extend system-id
spanning-tree mst 0-1 priority 8192
spanning-tree vlan 1-4094 priority 8192

 

We're a school district, and I set this up during the summer when very few staff were in the buildings. Reading up on  MSTP there were suggestions about creating regions and instances, so I added this:

 

spanning-tree mst configuration
name region1
instance 1 vlan 3-4, 6-8, 12-16, 100, 110, 120, 200, 300, 999-1000

 

I didn't see effects, positive or negative, to adding this. Are they necessary or helpful in any way, or should I just remove the region and instance to the core switch?

 

For further mitigation today I added "spanning-tree guard root" to all ports on the Catalyst 6509 and added this to the config:

 

spanning-tree portfast edge bpduguard default  

 

I'm hoping this will help prevent spanning tree from going totally haywire again.

2 Replies 2
GreenMan
Meraki Employee
Meraki Employee

This is from the Advanced MS Setup Guide:

 

Meraki switches do not support MSTP but are compatible and will see all MSTP instances as a single RSTP region.  [0]

 

You will, I'm sure, need to revert to a single instance, with something like:

spanning-tree mst 0 priority 8192

 

have a good read here:  https://documentation.meraki.com/MS/Deployment_Guides/Advanced_MS_Setup_Guide#Protocol_interoperabil...   and here:

https://documentation.meraki.com/MS/Port_and_VLAN_Configuration/Configuring_Spanning_Tree_on_Meraki_...

 

If in doubt, I'd suggest raising a case with Meraki Support.

Tony-Sydney-AU
Meraki Employee
Meraki Employee

@GreenMan is right. Be sure to use MST 0 (instance 0) for compatibility. This was discussed before on this other thread.

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