A HP ProCurve Switch is showing in the Logfile, that one Port is changing status from offline to online very often.
I 07/07/17 05:06:04 00076 ports: port 12 is now on-line
I 07/07/17 05:07:22 00077 ports: port 12 is now off-line
I 07/07/17 05:07:25 00435 ports: port 12 is Blocked by STP
I 07/07/17 05:07:27 00076 ports: port 12 is now on-line
I 07/07/17 05:10:49 00077 ports: port 12 is now off-line
I 07/07/17 05:10:51 00435 ports: port 12 is Blocked by STP
I 07/07/17 05:10:53 00077 ports: port 12 is now off-line
I 07/07/17 05:10:55 00435 ports: port 12 is Blocked by STP
I 07/07/17 05:10:57 00076 ports: port 12 is now on-line
First thought was that it is a Problem with the Connection, but does this exclude the Switch from being a Fault source?
Has it to be the cabling? Or could it be the Device on the other End.
Also it had a PoE Fault (the Warning in the first line), this happens roughly once per month.
The same Question here: Can I exclude the Switch from being the Source?
After Searching for the Definition of this Fault it says
"[The device] may have been disconnected, powered down or stopped working."
Here the Data from the Logfile:
W 07/08/17 10:47:53 00563 ports: port 1/12 PD MPS Absent indication.
I 07/08/17 10:47:53 00565 ports: port 1/12 PD Removed.
I 07/08/17 10:48:01 00560 ports: port 1/12 PD Detected.
Best Answer
Looks like a too long Ethernet run for PoE to me, you see the STP flap because STP starts by blocking the port by default, then bringing it online when it notices the port being an edge port, and then your device either draws too much current so that the voltage drops too much at it's end, shutting down the device to protect it from a brown-out condition. This removes the load, and the voltage jumps up again, restarting the cycle. Could also be a faulty PoE device.
According to ancient HP manual;
http://whp-hou9.cold.extweb.hp.com/pub/networking/software/59906044-e1.pdf