4 weeks ago - last edited 4 weeks ago
I spent a long time onsite today working through some messy POE/POE+ issues. The problem statement in a nutshell "2930M switch does not power camera".
The camera doesn't actually have a POE/POE+ input port, but instead has an ethernet port and 12V connector. An additional external box splits the POE+ connection from the switch into data (ethernet) and a separate power feed.
- Directly connecting the power splitter + camera to the 2930M POE+ port didn't power on the camera without configuration changes (see "Useful Commands" below).
- port would sometimes flap - power on/power off
- switch logfile indicated several POE related errors
- additional problems seemed to arise when three or mode cameras were connected
- multiple switch brands and models experienced similar or identical symptoms
Sample logfile entries
W 07/25/18 13:54:39 00564 ports: port 5 PD Invalid Signature indication. W 07/25/18 13:54:37 00562 ports: port 5 PD Over Current indication. I 07/25/18 13:54:37 00077 ports: port 5 is now off-line I 07/25/18 13:54:36 00565 ports: port 5 PD Removed. W 07/25/18 13:54:36 00562 ports: port 5 PD Over Current indication.
Example of excess power draw
5 Yes critical on value value 30.0 W 31.8 W Delivering 4 2 6 Yes critical on value value 30.0 W 18.4 W Delivering 4 2
In fact the 2930M switch is fully compliant with 802.3at - POE+, with support for a maximum of 30W. On several occasions, the switch reported 31.8W on the port - and shut down. This is exactly what it is supposed to do.
Even though the splitter specified 802.3at POE+ compliance, that seemed doubtful. The switch log entries were conclusive in pointing to a non-compliant endpoint.
External third-party POE injectors that supplied 35W have been used as the fallback solution.
The interface has some POE options; these ones helped:
poe-allocate-by value poe-value 30
In addition, this command run at the global level (ie not from the interface perspective) alloed the camera to power on:
power-over-ethernet pre-std-detect ports <port IDs>
Both should be used with caution.
Richard Litchfield, HPE Aruba
Network Solution Architect