Last week I updated the core switches at one of our sites to two new fancy HP 5406zl. Along with all the nice new features that came with these two beasts was PoE on all ports. All was good and well, until today, when the logs on one of the switches started filling up with 3 errors about PoE delivery on a specific port.
After a lot of cable-tugging and google, it turned out that a subcontractor had installed a small V1810-8G switch in the network. And among other things, these small buggers can be fed by PoE on Port 1. But since it was hooked up with a wall-wart, that collided with the PoE-feed. One would think that HP could put in a bit of error checking on the PoE side so that a device that already have a functioning power supply does not request a PoE-feed.
So, if you’re struggling with a log full of PoE errors (I got 110 000 events in half a week), do a quick google if the connected device supports PoE.