Should be a good test. My interpretation of what you've posted is that PVST+ is definitely running on the Cisco switch. From the bridge ID the bridge MAC is 00:1f:27:98:25:80 (the centre part of the bridge-id), the port ID is the part following the MAC, i.e. the 8019, which since these are all coming from the same port shouldn't change. The part in front of the MAC are the Bridge priority bits. Assuming PVST+ the first hex character (i.e. 4 bits) of the Bridge priority, '8', is the actual priority, 32768 (the default), then Cisco use the next 12 bits to identify the VLAN - I'm guessing this is part of the history as to why we can only go to 4096 VLANs, 12 bits. You should be able to match them up. Ultimately if there are Cisco PVST+ BPDUs (they're sent in a SNAP frame with a different multicast MAC) then the Meraki switches will just flood them across the network (as will any IEEE STP switch), that's the way its meant to happen, so they can 'find' other Cisco switches and share information. Unlike a standard IEEE STP BPDUs that are processed by the Meraki switch. However, the Cisco switch does actually send a standard IEEE BPDU too. Only for VLAN 1 though, so it can join the IEEE STP, or the CST in a MSTP environment. So if a Cisco switch is the root bridge for your network then it tends to work fine, if its not the root bridge (and especially if there are multiple Cisco switches running PVST+ in the network) then trying to make head or tail of the IEEE BPDUs and the Cisco BPDUs at each point in the network becomes a nightmare and you can end up with some very odd behavior/traffic flows. Ultimately (as I'm sure you know, and I'm only putting this here for completeness) the best option is to change all Cisco Catalyst switches that share a network with Meraki devices (or other IEEE STP based switches) to run MSTP, so they properly use the CST instance to interoperate with the Meraki devices.
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