9120AXI 802.3af POE

[awatson20]

We are in the process of replacing some older legacy access points with 9120AXI access points that will only temporarily be connected to switches that only support 802.3af(15.4) poe power.  These switches will be replaced with switches that will support POE+, but in the interim they will be only on switches that provide standard 802.3af poe.  My question is can the 9120AXI model AP;s function with only 15.4 max power per port in a limited mode? From looking at the data sheet it appears they can run in a limited mode with only 13.4 power required. I believe in this scenario the AP will cycle the led lights. Will they provide connectivity on 2.4, 5, or only one band to clients in this configuration? Is there any special configuration needed on the WLC for these to register?

[balaji.bandi]

For the new AP Cat 9K models required PoE+ as you mentioned for the AP to work as expected.( i would not suggest other method, since AP required correct power to work as expected.) if not users will have different issues of connectivity.

i will use legacy AP for some time until you fully replace with Cat 9300 or PoE+ switches.

[awatson20]

That is not possible since 9K access points require a minimum WLC code to be supported, and one that legacy access points cannot support. We are planning to replace these switches within a couple weeks, but we are performing the AP replacement first.  I just need to understand if the 9K access points will function at all(power up, register, provide connectivity to clients) in the interim on a port with only 802.3af poe.

[balaji.bandi]

AP power up - but Cat 9K radios required PoE+

[awatson20]

According to this data sheet they will operate in limited power.

[balaji.bandi]

yes Limited power - but that not show the information the AP work as expected outcome - its your call to make that decision.

we tried with Cat 3750 switch Cat 9K AP - that was not the outcome we expected.

[Leo Laohoo]

If the switches only support 15.4wac, do not make any attempts to upgrade the APs. 

At 15.4wac, the AP will be operating in half Tx power and 1x1:1.  WiFi experience will be absolutely trashed.  

[Karsten Iwen]

I wouldn't be afraid of running them on 802.3af if I knew that it is only temporary. Even with 1x1 on both radios the system is likely more powerfull than the system that you are replacing. You can control everything in power profiles:

https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/17-9/config-guide/b_wl_17_9_cg/m_access_point_power_control.html

[JPavonM]

Have you considered C9115?

It could have "lower capacity" but maybe the same one than your previous APs, but adding WiFi6 capabilities.

[Rich R · Accepted solution]

So as per the other answers - they WILL work.
I agree with @Karsten Iwen that as a temporary measure it's probably ok, but I'd get those switches upgraded ASAP and it would still be better to upgrade the switches first.
As per the data sheet: https://www.cisco.com/c/en/us/products/collateral/wireless/catalyst-9120ax-series-access-points/datasheet-c78-742115.html#Productspecifications

Catalyst 9120AXI, 9120AXE, 9120AXP

PoE power consumption

2.4-GHz radio

5-GHz radio

Link speed

USB

LLDP

802.3af

PoE

1x1

1x1

1G

N

13.4W

802.3af

PoE

2x2

N

1G

N

13.4W

802.3af

PoE

N

2x2

1G

N

13.4W

By the way - what document did you take that screenshot from @awatson20  ?
It looks similar to https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9100-access-points/215467-cisco-access-point-power-requirements-qu.html but better!