Mixed Cisco/Cisco Meraki Environment

[TheNino]

I had to introduce a Cisco switch into my Meraki environment a few months ago. In my topology map for one of my networks, the Cisco switch keeps jumping around where its connected to its neighbor. It should be connecting to the root bridge (my core switch via single mode fiber), but it shows its neighbor is the firewall or sometimes another switch. My STP bridge priority is set to my core switch (4096). The Cisco's uplink SFP port is the native VLAN 1, which is the management VLAN in my dashboard. 

On my Cisco switch, aside from some of the ports configured for the native VLAN 1, I have a ports configured for my security VLAN and wireless VLAN. I opened a case with Cisco and they state the Cisco switch is acting as the STP bridge for the Security and Wireless VLANs and therefore causing the switch to jump around on my topology map. 

I have several Meraki switches on different networks that have a mix of VLANs and do not exhibit this behavior. They all recognize the STP bridge priority I have set.

What can I do that will force the Cisco switch to recognize the STP bridge priority. Mind you, everything works, but it's concerning, especially if I will have to deploy more Cisco switches in the future.

Thank you in advance.

[alemabrahao]

It is recommended that you have VLAN 1 running on the trunk and that you use MSTP.

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

Even though your core switch has the lowest STP bridge priority (4096), STP operates per VLAN. So unless you've explicitly set the STP priority for each VLAN on your core switch, other switches (like the Cisco one) might become the root bridge for VLANs like your Security or Wireless VLANs.

[TheNino]

I had read the document you suggested. My VLAN 1 is set on the Trunk. All my uplink ports are configured for TRUNK VLAN 1. MSTP is compatible with RSTP, but not natively available in the Meraki Dashboard. My core switch is a Catalyst C9300, but it is Meraki not Cisco...

Perhaps RPVST+ is a viable option, but it can cause unexpected issues, as per the documentation.

[alemabrahao]

Use  MSTP. Avoid PVST, RPVST+, or any vendor-specific STP implementations, as they can cause instability or unexpected behavior in mixed environments.