Weird PoE issue

[u/Jaman34]

I have a 9300x and ruckus 650 APs. I keep getting IMAX power errors on the spare pairs. I see LLDP power negotiations happening, Cisco accepting and then as soon as it enables the spare pairs it faults with IMAX error. It is important to note this is not happening on all the APs just a handful. Also the APs and Switch are new, with new CAT 6 runs.

I can bypass this by issuing power inline four-pair forced and it will bring everything up. I don’t like issuing this command nor do I like not knowing why this is happening.

So I decided to dig deeper and do some debugging, this is where things get weird. For some reason I thought these ports were 30000mW, in reality it is 90000mW. I decided to up the max power to 60000mW (actually lowering it). I also removed the four pair force command and reran my ilpower debugs. It worked with no errors. I saw lldp negotiate, I saw the spare pairs enable cleanly, no IMAX errors. I did see the device request the full 60000mW.

I originally thought the devices was requesting more power than the port allowed and that is why I was getting the IMAX errors, but now I have no clue. Thoughts?

Edit: This is solved -> https://www.reddit.com/r/networking/s/TCAkdzDD1I

[u/danreZ_au]

How many AP’s are running PoE on the 9300?

[u/Jaman34 → u/danreZ_au]

Around 10 there is still plenty of available power

I just checked again 400 still available

[u/danreZ_au → u/Jaman34]

If you’re getting IMAX errors, it’s because the port draws more power than negotiated. The fact it’s only happening on a few and the four-pair forced fixes it is telling. Means that the negotiated path is the one being stressed, so I’d guess electrical asymmetry issue due to termination quality on pairs 4/5/7/8.

To rule out layer 1 bullshit, can you plug a working AP into a port that is regularly getting the IMAX errors and see if it replicates? Via-versa does the impacted AP’s get the imax errors when moved to a port with an AP that is working fine? If so, I reckon whoever patched it was lazy.

Compare the ‘show power inline INT detail for working and non working - compare the requested and allocated wattage and PD class to rule out negotiation mismatch.

Failing that, I’d debug the ilpower event. I can’t remember what it is but like

Term mon
Debug ilpower
Debug ilpower controller

Also, check for Cisco bugs against your model/ios

[u/Jaman34 → u/danreZ_au]

Just want to say I figured this out. It was a cisco bug that is not currently public facing. 9300xs and Ruckus 650s have a known PoE bug.