Why all C9115 APs consume the maximum amount of power at idle state?

[schulcz]

Hi Guys,

Currently I make a new wireless deployment with C9115 APs in the network. Most of the APs not configured yet, just they was put under "ap locations" (tags configured), but no wlans was configured under these tags. However I saw in switches (9300 series) all of the APs (Both those that are already configured and have at least one active SSID and those that are not) consumes 24.1W, and wondering why? (cdp is enabled on all switchports)

sw1>sh pow inl

Module   Available     Used     Remaining
          (Watts)     (Watts)    (Watts)
------   ---------   --------   ---------
1           514.0      482.0        32.0
Interface Admin  Oper       Power   Device              Class Max
                            (Watts)
--------- ------ ---------- ------- ------------------- ----- ----
Gi1/0/1   auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/2   auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/3   auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/4   auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/5   auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/6   auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/7   auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/8   auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/9   auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/10  auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/11  auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/12  auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/13  auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/14  auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/15  auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/16  auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/17  auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/18  auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/19  auto   on         24.1    C9115AXI-E          4     30.0
Gi1/0/20  auto   on         24.1    C9115AXI-E          4     30.0

Another interesting question is, why does the AP consume 24.1W when the datasheet shows 20.4W as the worst consumption?

[Leo Laohoo]

Nothing wrong with that. 

The USB port can be disabled and it will save some power.

[schulcz]

I understand it, but I worked with many AireOS APs and never saw that an AP consumes 24.1W under normal usage. AireOS APs generally consumes a couple Watts in idle mode, and between 10-15W with some clients. In comparison, I'm shocked that the C9115 series can consume 24.1W with the radios turned off, it's not so green by Cisco.

[Leo Laohoo]

---

@schulcz wrote:
AireOS APs generally consumes a couple Watts in idle mode, and between 10-15W with some clients. 

---

I have never seen AireOS APs in "idle" mode -- It is either on or off and nothing in between.

[balaji.bandi]

Can you post the output on what switch model ? show output help us,. in general, I have observed 21. X full functioning AP - on Cat 9300 switch.(may be due to USB)

https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9100-access-points/215467-cisco-access-point-power-requirements-qu.html

[schulcz]

We use C9300-48P switches with default power supply (715W), I know I can use one more AP on the 21th port, but but I was shocked that these APs are so energy wasting when idle, with radios turned off by config.

[balaji.bandi]

May be you can fine tune once they join WLC and depends on requirement.

just took my AP and connected, it taking as you claim

#show power inline Tw1/0/1 detail
Interface: Tw1/0/1
Inline Power Mode: auto
Operational status: on
Device Detected: yes
Device Type: cisco C9120AXI-E
IEEE Class: 4
Discovery mechanism used/configured: Ieee and Cisco
Police: off

Power Allocated
Admin Value: 60.0
Power drawn from the source: 23.2
Power available to the device: 23.2

Actual consumption
Measured at the port: 6.6
Maximum Power drawn by the device since powered on: 7.3

Absent Counter: 0
Over Current Counter: 0
Short Current Counter: 0
Invalid Signature Counter: 0
Power Denied Counter: 0

Power Negotiation Used: CDP
LLDP Power Negotiation --Sent to PD-- --Rcvd from PD--
Power Type: - -
Power Source: - -
Power Priority: - -
Requested Power(W): - -
Allocated Power(W): - -