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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.
  • Blocked by STP could very well mean you have a spanning-tree loop on that port. – user36472 Jul 20 '17 at 9:34
  • But if it is just a single link? What could that mean? – DOWJ Jul 20 '17 at 10:02
  • If you are sure it's a single link then i guess that is pretty strange. – user36472 Jul 20 '17 at 10:22
  • I think I need to check that – DOWJ Jul 20 '17 at 10:41
  • If you have a wireless setup, depending on how that is configured and if it's controller based, a computer could create a loop via wired to wireless connection. I've seen that a few times. – user36472 Jul 20 '17 at 10:57
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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;

Port < port-# > PD MPS Absent indication.
The switch no longer detects a device on < port-# >. The device
may have been disconnected, powered down, or stopped
functioning. 

http://whp-hou9.cold.extweb.hp.com/pub/networking/software/59906044-e1.pdf

| improve this answer | |
  • Thank you very much for the answer. A crossover connection was the cause for the overcurrent. – DOWJ Nov 28 '17 at 7:01
  • That sounds quite interesting, do you mean a crossed connection in the cable, or a crossover cable? PoE should work even with crossed cables, but I've never tried it with a physically defect cable. – Stuggi Nov 29 '17 at 6:02
  • It was a hardwired cable, on one side with a wiring and on the other side with b wiring. Since that is changed I didn't hear anything again. – DOWJ Nov 29 '17 at 6:07
  • Okay, that's a bit interesting, I'll have to try that out when I get home from work :). If you think my answer is satisfactory, would you please accept it so this question get's marked as answered? – Stuggi Nov 29 '17 at 6:10

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