Wired Intelligent Edge (Campus Switching and Routing)

New Contributor

Aruba 2920 port Blocked by STP - Errors

I'm seeing these errors all day at a few of my remote location switches.

**From log on switch**

00076 ports: port 14 is now on-line
00435 ports: port 14 is Blocked by STP
00077 ports: port 14 is now off-line


**From IMC**

iMC alarm system found event (The interface 14 is UP.) and event (The interface 14 is DOWN.) had 3 intermittent failures


All the ports doing so have a Cisco aironet 3600 series AP connected to them. Has anyone see then before and know what is going on? I was guessing maybe an LLDP or power negotation failure. Power draw is around 80w of the 370w available.


Thanks in advance.


MVP Guru Elite

Re: Aruba 2920 port Blocked by STP - Errors



By default when port is UP (and there is not admin-edge port), it is blocked by STP for 3 sec (with RSTP)


I think, you need to look access point log..

PowerArubaSW: Powershell Module to use Aruba Switch API for Vlan, VlanPorts, LACP, LLDP... More info

PowerArubaCP: Powershell Module to use ClearPass API (create NAD, Guest...) More info

PowerArubaCX: Powershell Module to use ArubaCX API (get interface/vlan/ports info)

PowerArubaIAP: Powershell Module to use Aruba Instant AP

PowerArubaMC: Powershell Module to use Mobility Controller / Master

ACMP 6.4 / ACMX #107 / ACCP 6.5 / ACSP
New Contributor

Re: Aruba 2920 port Blocked by STP - Errors

Thanks, I have opened a case with Cisco TAC.

MVP Expert

Re: Aruba 2920 port Blocked by STP - Errors



As noted by alagoutte, the STP port blocking is a default behavior when a port first comes up, and normally clears automatically. If you're seeing this occurring continually, the port is bouncing, and that could be either a power delivery issue or a problem with the connected AP itself causing it to continually reboot. 


Are you seeing anything in the switch event logs indicating a PoE delivery error on the switch port itself?

Matt Fern
Senior Technical Marketing Engineer, Aruba Switching

Aruba, a Hewlett Packard Enterprise company

T: 916.540.1759  |  E: mfern@hpe.com   |   Matt @ Twitter
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