I have seen logs like this before, and sometimes it is hard to tell if it is the port flapping or spanning tree. The latest firmware addresses some scenarios, and would be worth scheduling to update. [URL] Setting the edge ports to portfast can help interfaces come back up into the forwarding state quicker.  Do you have spanning tree priorities manually set on the switches? This helps to ensure that the core switch is the root switch.  How often is this occurring? Are there any topology changes being recorded? 
Hello, Does someone know how tro read these error reported in log from a 6 switches N2048? We experience some network performance problem and would like if it could an indication? Our current firmware is: 6.2.1.6.  Error Logs:  does upgrade to lastest firware will solve ports shutdown and up?
multiple shutdown / up message on 6 SW stack?