1. Are we seeing any continuous port flaps between these switches on active port# 1:1, 2:1 ? If yes, did you try to eliminate the cable issues or any other symptom triggering the topology change?
2. Is it new implementation or any recent configuration/firmware changes made?
3. Provide us the "show configuration stp" and "top" output.
4. What is the current EXOS version and switch type?
5. Is there any suspicious logs generated in switch?
6. Did you configure edge ports?
The configuration on Extreme device looks fine.
The below link gives you the basic idea of configuring RSTP in Summit/BlackDiamond switches:
https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-configure-RSTP-in-EXOS?_ga=2.148314807.1012568893.1502325830-1247773174.1501480829
The below link is for the user guide to EXOS and sample configuration is available for your reference:
https://extrcdn.extremenetworks.com/wp-content/uploads/2014/01/EXOS_Concepts_Guide_15_4.pdf?_ga=2.171259424.1012568893.1502325830-1247773174.1501480829