Same document referenced above: The default priority for all Meraki switches is 32768. It is recommended that you set the priority of your desired root bridge to 4096 to ensure its election. The root bridge should be a switch in the center of the network, near high traffic sources (such as servers), to optimize traffic flow across the network. Using priority 0 is also acceptable for the root, but leaves no room for modification when replacing a core switch in production or modifying behavior temporarily. It is best practices to set a layered approach to the STP priorities in a network. For instance, if there is a clear Core <> Distribution <> Access Layer, priorities should be Core (4096), Distribution (16384), and Access (61440). At no point in a production network should you leave the any switch at its default configurations. I set my MS425s at 4096 and everything else at 61440. If you were to type loopguard in the community search field you will see several other posts that have issues with it, some have shared their thoughts/feedback on the use of loopguard. The Meraki Best Practice Designs and Deployment Guides that I tend to follow or mirror in my setups/configurations show core switch downlinks with rootguard.
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