3802 PoE Power draw.

[JASON SIMMONS]

How much power are your 3802 access points drawing from your PoE switches?  Are they Cisco switches?  We have an installation of 3802s connected to a non-Cisco 802.3at enabled switch and we're seeing a maximum 11w to each AP.  A consultant was expecting to see somewhere between 15-25w.  It appears that all the radios are up but users have been complaining about peformance and connectivity since they were installed.

[Scott Fella]

12W on a Meraki switch. No issues with connectivity. 

[JASON SIMMONS]

I learned and configured the switch to statically assign 30W and I'm still getting 11.x watts, although I saw it jump to 13w once.  Cisco TAC basically said it isn't compatible and told me to buy an injector... 

I honestly don't know if power is the problem.  I just know installing the older switches worked. 

I don't know...

Thanks for your replies.

[Leo Laohoo]

---

@JASON SIMMONS wrote:

I learned and configured the switch to statically assign 30W and I'm still getting 11.x watts, although I saw it jump to 13w once.  Cisco TAC basically said it isn't compatible and told me to buy an injector... 

I honestly don't know if power is the problem.  I just know installing the older switches worked. 

---

No, it's a bug with the AP software.  It seems that AP is having difficulty negotiating power if it's not Cisco.  

I believe TAC would say that "it's not supported".  

[Scott Fella]

Power should not be a problem… Mine changes to up to 13W and drops down also.

[hogerappa]

Disable CDP on Juniper if it's enabled.

It's possible that Juniper is bringing a wrong PoE budget information via CDP.

[JASON SIMMONS]

Juniper does not support CDP.

[Shankar Ramanathan]

Just checking. Was this ever resolved?

[JASON SIMMONS]

No we never determined root cause.  We replaced the APs.

[derobbacher]

Hello,

our 3802i show the same behaviour in power consumption on our Cisco SG350-10P switches:

On Port gi1 is a 3802i using only 10,8 Watt and on Ports gi2-gi4 3 old Cisco 1142-APs are connected.

Unit Module Nominal Consumed Temp SW PSE chipset
Power (W) Power (W) (C) Version HW Revision
---- -------------- --------- ------------ -------- ------------- -----------------
1 SG350-10P 62 57 (92%) 73 23.190.18.3 PD69208 - 0x4A02

Interface Admin Oper Power (W) Class Device Priority
---------- ---------- ----------- ----------------- ----- -------------- --------
gi1 Auto On 10.800 4 low
gi2 Auto On 9.600 (15.400) 3 low
gi3 Auto On 11.500 (15.400) 3 low
gi4 Auto On 10.300 (15.400) 3 low

The show cdp nei detail reveals also the Full/Half-Duplex-Mismatch Bug with the new Csico 2800/3800-series-APs:

Device-ID: D20-HVT
Advertisement version: 2
Platform: cisco AIR-AP3802I-E-K9
Capabilities: Router TransBridge
Interface: gi1, Port ID (outgoing port): GigabitEthernet0
Holdtime: 114
Version: Cisco AP Software, ap3g3-k9w8 Version: 8.3.141.0
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2014-2015 by Cisco Systems, Inc.
Duplex: half
Primary Management Address: IP 10.232.4.193
Addresses:
IP 10.232.4.193
---------------------------------------------

But cdp does not show any info about the Power drawn.

The WLAN AP and the antennas are working.

We are not sure about any restriction on WLAN AP functionality.

I fear that maybe special functions like beamforming will not working with only 10 Watt.

But I'm not sure.

Does anyone know if this is a nice power-saving-feature or a bug with the Cisco 3802-APs?

Thank You

Wini

[derobbacher]

Hello,

our 3802i show the same behaviour in power consumption on our Cisco SG350-10P switches:

On Port gi1 is a 3802i using only 10,8 Watt and on Ports gi2-gi4 3 old Cisco 1142-APs are connected.

One can see that the nominal value in brackets () is missing for the 3802-AP in comparision to the old 1142-APs:

Unit Module Nominal Consumed Temp SW PSE chipset
Power (W) Power (W) (C) Version HW Revision
---- -------------- --------- ------------ -------- ------------- -----------------
1 SG350-10P 62 57 (92%) 73 23.190.18.3 PD69208 - 0x4A02

Interface Admin Oper Power (W) Class Device Priority
---------- ---------- ----------- ----------------- ----- -------------- --------
gi1 Auto On 10.800 4 low
gi2 Auto On 9.600 (15.400) 3 low
gi3 Auto On 11.500 (15.400) 3 low
gi4 Auto On 10.300 (15.400) 3 low

The show cdp nei detail reveals also the Full/Half-Duplex-Mismatch Bug with the new Csico 2800/3800-series-APs:

Device-ID: D20-HVT
Advertisement version: 2
Platform: cisco AIR-AP3802I-E-K9
Capabilities: Router TransBridge
Interface: gi1, Port ID (outgoing port): GigabitEthernet0
Holdtime: 114
Version: Cisco AP Software, ap3g3-k9w8 Version: 8.3.141.0
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2014-2015 by Cisco Systems, Inc.
Duplex: half
Primary Management Address: IP 10.232.4.193
Addresses:
IP 10.232.4.193
---------------------------------------------

But cdp does not show any info about the Power drawn.

The WLAN AP and the antennas are working.

We are not sure about any restriction on WLAN AP functionality.

I fear that maybe special functions like beamforming will not working with only 10 Watt.

But I'm not sure.

Does anyone know if this is a nice power-saving-feature or a bug with the Cisco 3802-APs?

Thank You

Wini

[patoberli]

Have a read here: https://www.cisco.com/c/en/us/support/docs/field-notices/702/fn70252.html It seems you should upgrade to 8.3.150.0 or newer.  

Regarding the power, you have a 60 W budget, of which ports 2-4 already use a lot. You actually already use 92% of available power, not enough for the 3800 left.