We have 3 DES-1228P switches that we are currently using for PoE for a group of devices. One switch is providing PoE for Cisco Aironet devices, and another switch is providing PoE for VoIP speakers in the ceiling.
I've noticed over the last few days a port will go out on the switch. Unplugging the cable above or below will re-establish connectivity with the problem port, and the newly unplugged port will have problems coming up.
For example, let's say port 7 is a top port and it's out (no lights). Port 8 is below port 7. If I unplug port 8, port 7 will come back up and resume activity. If I replug the cable back into port 8, it will not back up. (Hope this isn't confusing, because there's more.)
Now port 7 is up and port 8 is out. I just reseated the cable into port 8. If I unplug port 7, port 8 will come up again and resume activity. If I reseat the cable into port 7, it won't come back up unless I remove the cable from port 8 again.
Here's the interesting issue...
These are all new switches. It's not just an issue that I've experienced with ports 7 and 8 on just one switch. I've seen this strange anomaly with different ports on all 3 switches.
Going back to my example, I have found that if I unplug 8 just enough -- don't completely remove the cable -- but unplug it enough for port 7 to come up and quickly reseat the cable I can usually get both ports up and running again.
Has anyone else experienced this problem? Does anyone know if upgrading the firmware would resolve the issue?