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September 23rd, 2021 19:00
Port up but no MAC address
I have an N2048P in a warehouse driving a bunch of PoE AP's. Unfortunately the previous person didn't document where the AP's were located. I've pretty much figured out where they all are by looking at the mac address table on the ports and working from there.
However I have a few mystery ports, a "show interfaces status" shows them up and a "show power inline" shows there is definitely something being powered on those ports. However I can't get any MAC address data on those ports. If I physically disconnect the ports or I shut them down they come back up but again no MAC address is found.
It's virtually impossible to physically trace these lines through the warehouse and I know I don't have any "missing" AP's also the power consumption on these ports is really low (1800) so that makes me think they aren't AP's. Does anyone have any idea why a device wouldn't be showing a MAC address on the switch?
I had one thought that might explain it but I'm not sure so if anyone could also comment on my idea I'd appreciate it. I know they previously had used some line extenders on some of these lines, could they be PoE extenders? That would draw some power but they wouldn't have MAC addresses right?
Thanks
DELL-Joey C
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September 24th, 2021 00:00
Howdy @JohnYL,
Your thoughts might be correct, it could be a PoE extender that might not have MAC addresses to be detect. I've spoken to my colleague about it, he did mention most devices when it is connect to switch do have MAC address. His point of view is to check if the switch's port that does not show any MAC address, try check if the port is faulty, PoE chip might be faulty. Is it possible to swap ports to check if any faults detected within the port itself. If all else is fine with the switch, you can conclude that the device which is connected has no MAC address to be detected.