PoE CW9166I-E

[Moudar]

Hi

Using the CW9166I-E APs with USB port enabled is 30,5 Watts. The switch shows 30 watts:

sh power in

Module   Available     Used     Remaining
          (Watts)     (Watts)    (Watts)
------   ---------   --------   ---------
1           240.0       60.0       180.0
Interface Admin  Oper       Power   Device              Class Max
                            (Watts)
--------- ------ ---------- ------- ------------------- ----- ----
Gi1/0/1   auto   off        0.0     n/a                 n/a   30.0
Gi1/0/2   auto   off        0.0     n/a                 n/a   30.0
Gi1/0/3   auto   off        0.0     n/a                 n/a   30.0
Gi1/0/4   auto   on         30.0    CW9166I-E           4     30.0
Gi1/0/5   auto   off        0.0     n/a                 n/a   30.0
Gi1/0/6   auto   off        0.0     n/a                 n/a   30.0
Gi1/0/7   auto   off        0.0     n/a                 n/a   30.0
Gi1/0/8   auto   on         30.0    CW9166I-E           4     30.0
--------- ------ ---------- ---------- ---------- ------ -----
Totals:          2    on    60.0

Disabling the PoE port does not reduce power consumption to 25.5W as stated in the AP datasheet:

The switch still shows a power consumption of 30W. What's going on here?!

[Scott Fella]

I'll be honest, I only look at that for the required power.  I don't think I have ever seen ap's actually show the min W that it shows on the datasheet.  I have a mix of ap's and they are all over.

[Moudar]

I got a bunch of different APs that shows lower Watts.

Example: 9120 shows this with disabled USB port:

Gi1/0/37  auto   on         23.2    C9120AXI-E          4     30.0

but it shows 30W if USB port is enabled!

[Scott Fella]

I see the same, even for Meraki ap's.... I wouldn't worry about it unless your budgeted using the lowest power and might run out of available PoE.

[Leo Laohoo]

Reboot the AP.

[Rich R]

We've had this argument with the BU and they do not understand - even our account team have given up trying to explain it to them.  We now work out what the maximum required AP PoE power is (including cable loss) and statically configure the max power on the PoE port to prevent the APs from requesting full power regardless (which is what they do by default).  The data sheet specifies the maximum consumed power but the APs still request full power anyway.  If your power budget is tight then setting static max is the only way to prevent the AP from requesting full power regardless.

show power inline Gi1/0/37 detail

will show the actual power consumption which is inevitably much lower than what the AP has reserved and matches the data sheet requirement (+ cable loss depending on cable).

You'll usually need to add 5 to 10% to the datasheet number to ensure the AP still gets full power.

ps: you said "Disabling the PoE port" @Moudar - obviously meant to be "Disabling the USB port" <wink>

[Moudar]

sh power in gigabitEthernet 1/0/4 detail
 Interface: Gi1/0/4
 Inline Power Mode: auto
 Operational status (Alt-A,B): on
 Device Detected: yes
 Device Type: cisco CW9166I-E
 Connection Check: n/a
 IEEE Class (Alt-A,B): 4
 Physical Assigned Class (Alt-A,B): 4
 Discovery mechanism used/configured: Ieee and Cisco
 Police: off

 Power Allocated
 Admin Value: 30.0
 Power drawn from the source: 30.0
 Power available to the device: 30.0
 Allocated Power (Alt-A,B): 30.0

[Leo Laohoo]

Disable CDP on the switch and reboot the AP. 

If this works, then this could be CSCwj60401.

[Moudar]

It looks like my case is the bug!

The switch is C9200CX-8P-2X2G and runs 17.12.04

Is there any way to fix that?

[Mark Elsen]

 - @Moudar The particular bug report : https://quickview.cloudapps.cisco.com/quickview/bug/CSCwj60401
                    mentions Fixed Releases for the AP (not the switch) , 

 M.

[Leo Laohoo]

Raise a TAC Case and demand for an SMU.

[Rich R]

1. CSCwj60401 is about the AP not requesting enough power (only requesting POE+ 30W from a UPOE switch instead of UPOE 30.5W)
2. @Moudar is complaining about the AP requesting too much power (when USB disabled) 30W instead of 25.5W.
3. The switch is POE+ not UPOE so the AP cannot request more than 30W, so CSCwj60401 is not applicable in my opinion.
4. Since the fix for CSCwj60401 is in the AP code it would be in an APSP not a SMU, but given that it's already fixed in the released version of 17.15.2 I think it's unlikely to go into a 17.12.4 APSP at this point and more likely will just be included in the next 17.12 release (17.12.5) although just realised 17.12.4 is the switch IOS - what version is the WLC running @Moudar ? (remember to always provide WLC code version)

[Moudar]

WLC#sh ver
Cisco IOS XE Software, Version 17.12.04
Cisco IOS Software [Dublin], C9800 Software (C9800_IOSXE-K9), Version 17.12.4, RELEASE SOFTWARE (fc3)

[Rich R]

Noted - so WLC is also 17.12.4.  Obviously also make sure you have the 17.12.4 SMUs and latest APSP installed as per the TAC recommended link below.

[Leo Laohoo]

APSP8 (C9800-universalk9_wlc.17.12.04.CSCwn86874.SPA.apsp.bin, 31 January 2025) claims to fix this bug.