All Cisco Network - Replacing Core With 425 Stack

[jwwork]

Our entire network is Cisco (6509 core and 3560/2960 edge) and we are going to replace that core with a Meraki MS425 stack.  The plan is that eventually all the edge will move to Meraki as well.  The Cisco side is all configured for rapid-pvst and my testing shows that with the 425 STP priority set to 0 and a Cisco switch trunked off of it, the Meraki only becomes root on vlan 1.  Just wondering if anyone else in the scenario has done this and how you configured spanning tree.

Thanks!

[PhilipDAth · Accepted solution]

Change your other Cisco devices to using MST before you integrate Meraki.  The Cisco Enterprise per VLAN RSTP implemention can cause all sorts of issues when used with Meraki.

I would go with a simple MST design with a single area (so you can simply issue the command "spanning-tree mode mst" and nothing else).  I would also do this since you are phasing out the old Cisco Enterprise kit.

Try and avoid layer 2 loops in your design while you have both sets of kit deployed.

If you have much multicast in your network use the beta software 10.18 (or better if it has come out by then).  Otherwise 9.36 should be fine.

[jwwork]

Ok that's what I was planning on.  I have also read that it's very important when moving the existing Cisco environment to MST that I make sure all trunks are trunking all vlans and that all vlans exist on all switches (since I will be mapping all vlans to the same MST instance).  Is that accurate?

[PhilipDAth]

You want everything to have the same VLAN topology, and the safest way to do that is to trunk all VLANs on all ports.

All VLANs are mapped to the default MST instance by default.

[BadOscar]

I did a similar rip and replace - I ended up using CIDR on each side of my core links to remove layer 2 vlans  traversing my uplinks - set my root on each side and it's running much better now - I struggle with no pvst - I did set my cisco switches / stacks to mst mode but that did not resolve my issues.  I don't allow all vlans across any trunks, I only allow the vlans that are needed - I am always very careful about having the same settings on each side of the link. I miss not being able to do "no spanning-tree vlan#" .....