I tested two things.
Prime:
1. Created two port groups. One group has ports we want to monitor and another group we don't want to monitor.
2. Monitor / Monitoring Tools / Alarm Policies / Edit Interface Alarm Policy / Select switch model and User Defined / Under System Defined, select Trunk Ports and Link Ports / User Defined Ports, select the port group that has ports you want to monitor.
3. Click drop down and Activate
4. Click Save and Activate.
5. Repeat steps 2 except you will select Access Ports / User Defined Ports, select the port group that has ports you don't want to monitor.
6. Click drop down and select Suppress.
7. Save and Activate.
8. check log on the switch when a port goes up and down.
On the switch: I ended up using this one, much simpler.
1. Deleted the port groups I created.
2. Monitor / Monitoring Tools / Alarm Policies / Select Interface Alarm Policy / Reset to Default
3. issue interface range command on access ports you don't want to monitor. In 3850 case, I use no snmp trap link-status.
4. check log on the switch when a port goes up and down.
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