Curious how you have the exact same question as @nadalfan1984 had here back in FEB/19 🙂 :
https://community.meraki.com/t5/Switching/MX250-RSTP-Questions/td-p/38720
@nadalfan1984 wrote:I'm having a hard time understanding the Meraki MX250 BPDU forwarding process. Since Meraki runs RSTP, to my knowledge, any physical loop will be blocked regardless of VLAN configuration (unlike PVST in Cisco). So does the MX250 just forward all BPDUs to all connected LAN interfaces? My assumption is as follows.
Note: All ports are forwarding unless there is an X specified for the link in the diagram
- Agg1 switch is the root switch in the topology so all connected interfaces go designated/forwarding
- Agg1 BPDU is sent out on port 22 to Agg2 & port 24 to MX250-1
- MX250-1 forwards Agg1 BPDU out of all LAN ports
- Agg2 now receives Agg1 BPDU on port 24 from MX250-1 and then blocks the connection since it already has a better path to Agg1 (root).
- I don't understand how all 3 connections from Dist2 to MX250-1 are in the forwarding state? If all BPDUs are being blindly forwarded by the MX250-1 (similar to a hub) then two of the connections would end up going to backup port state.
- All switches are Meraki and RSTP is in use throughout the network
Anyways, I'm very confused! Any help would be much appreciated!
Answer can also be found there...
