I have two MX 250's, one is set up as the Primary and the other is set up as the Spare. They connect to two switch stacks. One switch stack is connected on a 1Gbps line to the Primary, with another 1Gbps line to the Spare MX. Both with RSTP enabled and forwarding. The second switch stack is connected to the primary on a 10Gbps fiber line with RSTP enabled and is forwarding. When I connect the the Spare MX to a 10Gbps fiber line, to the second switch stack with RSTP enabled, the network crashes and the event log reads mac flapping. I set the Spare MX 10Gbps fiber line to STP guard > Loop guard. The network did not crash but, the port turned amber in the Meraki dashboard and had a "high rate of STP topology changes" note. The goal is to have the Spare MX connected to both switch stacks and the network to stay up if the Primary MX fails and rolls over to the Spare MX. Are my MX's setup correctly? If the Primary MX fails will it be seamless roll over to the Spare MX?
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