Aruba s2500 spanning tree topology change issues


New Member
Apr 9, 2020
Hey guys (and a few gals presumably), wanted to post here and see if anyone can assist as I am fairly in the weeds. I am in the process of upgrading my network to 10g and started by purchasing 2x Aruba S2500-24P due to recommendations from the forum. I got them both reset and upgraded per @ViciousXUSMC and the thread Aruba MAS series SFP+ & POE+ switches sub-$100. I stacked them as such:

Stack works just fine and communication is solid across the switches. Port 0/0/20 is an uplink AP that acts as a bridge from another location in the house unable to directly cable. Uplink is solid, and before you ask, yes I am uplinking 10g across WiFi (really just to obtain ISP access).

The issue I'm having is when a device connects and/or reconnects to the switch. Example: rebooting the server utilizing LACP Port Channel PC0 (1/1/0 and 1/1/1). When I reboot this server on PC0 the switch stack triggers MAC flushing of the ports due to TC (see system log). With the default port configurations this TC would cause the AP bridge to become unresponsive for approximately 4 minutes. Equipment on the Aruba switch side still had local connectivity, but no internet access due to AP unresponsiveness. After some troubleshooting and research I realized it was the TC causing the unresponsiveness and attempted to mitigate STP on port 0/0/20 by enabling BPDUFilter. Enabling the filter has reduced the outage from ~4min to now about 20-25s. I have been unable to completely eliminate any outage yet despite trying the following on 0/0/20:
  • portfast enable
  • portfast trunk enable
  • bpdufilter default enable
So, I'm currently left with a 20-25s outage when the network changes on the switch side. While I have learned enough to make these changes and configurations, I am in the weeds as far as STP concepts and potential culprits in this scenario. Any assistance and guidance is GREATLY appreciated!!

System log and configurations:
Pastebin System Log
Pastebin 0/0/20 Running Config
Pastebin STP Detail
Pastebin 0/0/20 STP


New Member
Jan 1, 2014
your interface config shows 0/0/20 is not running portfast, need a pvst-profile defined and associated to the interface.

example config:
interface-profile pvst-port-profile "PortFast"
interface gigabitethernet "0/0/20"
pvst-port-profile "PortFast"