Description

Some new-model Cisco WAPs such as Catalyst C9130AXI and C9120AXI cannot be up via LLDP PoE negotiation on an EX3400 switch.

Symptoms

The concerned WAPs are Cisco Catalyst C9130AXI and C9120AXI, which running LLDP POE negotiation.

All WAPs are not able to negotiate with Juniper switches by running LLDP and turns into "low power mode".

Logs from Cisco WAP:
May 24 21:26:21 powerd: lldp0: LLDP PoE negotiation START
May 24 21:26:53 powerd: lldp0: LLDP PoE negotiation timeout !!
May 24 21:26:53 powerd: sending powerd message
May 24 21:26:53 powerd: send ipc_socket_process: 4
May 24 21:26:53 powerd: ps: Power mode: Degraded/Reduced Power, power_detection: DC_adapter(FALSE), PoE+/802.3at(30000 mWatt)
May 24 21:26:53 powerd: ps: End: System running on low power @ 30000 mWatt from port0

Solution

1. Juniper switch’s poe command, “show poe int ge-0/0/47”, will show real-time power draw, whereas Cisco switches “show power inline gigabitEthernet 0/2” will only show its maximum power it can provided, and this always made people confused and will assume Cisco WAP will consume 30watt straight on Cisco switches:

Juniper:
root> show poe interface ge-0/0/47
PoE interface status:
PoE interface : ge-0/0/47
Administrative status : Enabled
Operational status : ON
Power limit on the interface : 25.5W (L)
Priority : High (L)
Power consumed : 10.7W
Class of power device : 4
PoE Mode : 802.3at
(L) LLDP-negotiated value on the port.
 
Cisco:
switch# show power inline gigabitethernet 0/2
Interface Admin Oper Power Device Class Max (Watts)
--------- ------ ---------- ------- ------------------- ----- ---------------------------------------------------------
Gi0/2 auto on 30.0 C9130AXI-Z 4 30.0

2. Cisco switches can also display real-time poe usage by issue command: “show power inline gi0/2 detail”. With keyword “detail” at the end of the command, the power draw/consumption figure is almost identical with Juniper switches.
switch#show power inline gi0/2 detail
Interface: Gi0/2
Inline Power Mode: auto
Operational status: on
Device Detected: no
Device Type: cisco C9130AXI-Z
IEEE Class: 4
Discovery mechanism used/configured: Unknown
Police: off

Power Allocated
Admin Value: 30.0
Power drawn from the source: 30.0
Power available to the device: 30.0

Actual consumption
Measured at the port: 11.1
Maximum Power drawn by the device since powered on: 11.5

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): - -

Four-Pair PoE Supported: No
Spare Pair Power Enabled: No
Four-Pair PD Architecture: N/A

3. There are two USB status of Cisco WAP from WLC GUI.
**1. USB Interface Operational State
**2. USB Module State.

a. By default, the WLC will set Cisco WAP to USB Interface Operational State Disabled and USB Module State Enable. In other words, there is no function of USB interface. 
So, when connected phone to WAP’s usb port, no message pop up from phone, and there is nothing showing up from WAP logs, also the phone didn’t get power charged from WAP’s usb port. This is confusing, it looks like USB interface is disabled, but it is NOT.

b. To disable USB interface completely for this new Cisco WAP, from GUI, USB Interface Operation State needs to be Disabled as well as USB Module State."


4. Conclusion:
a. Cisco switches and Juniper switches showing identical real-time power draw by adding keyword “detail” at the end of command.
b. Cisco WAP’s USB interface is disabled and USB Module is enabled by default. This will bring the WAP to low power mode if it is connected to any 802.3AT/POE+ switches.
c. Both USB Operational state and USB module state will need to disable to bring the WAP to full-power mode.
d. With C9130AXI and C9120AXI operates at “low power/degraded power” mode, it caused by its own USB module.
Finally, by disabling USB interface on WAP and USB module from WLC, the logs from C9130AXI/C9120AXI WAP shows “full power”, and the radio power change from power “6” to power”4” as per logs.

** With LLDP only (Juniper switches, ex3300 with firmware JUNOS 15.1R7-S12, ex3400 with firmware 18.2R3-S5.3 or JUNOS 20.4R3-S3.4 ).
 
C9130AXI/C9120AXI WAP logs:
Jun 19 05:38:48 powerd: cdp0: CDP PoE negotiation timeout !!
Jun 19 05:38:49 powerd: lldp0: LLDP PoE negotiation START
Jun 19 05:38:50 powerd: lldp0: LLDP PoE negotiation success!
Jun 19 05:38:50 powerd: sending powerd message
Jun 19 05:38:50 powerd: send ipc_socket_process: 4
Jun 19 05:38:50 powerd: ps: Power mode: Full-Power, power_detection: DC_adapter(FALSE), PoE+/802.3at(29857 mWatt)
Jun 19 05:38:51 powerd: ps: End: System running on full power @ 29857 mWatt from port0
Jun 19 05:38:51 kernel: [*06/19/2022 05:38:51.1944] AP is in good condition, BLE is off
Jun 19 05:38:51 kernel: [*06/19/2022 05:38:51.1945] Set radio wifi0 power 4 antenna chain 4 15
Jun 19 05:38:51 kernel: [*06/19/2022 05:38:51.1945] Set radio wifi1 power 4 antenna chain 8 255
**********************************************************************************************************

** With CDP/LLDP negotiation failed, it still run as full-power.(Juniper ex3300 with firmware 15.1R6-S2.1, ex3400 with firmware JUNOS 18.1R3-S2.5)
 
C9130AXI/C9120AXI WAP logs:
Jun 19 04:59:26 powerd: cdp0: CDP PoE negotiation START
Jun 19 05:00:26 powerd: cdp0: CDP PoE negotiation timeout !!
Jun 19 05:00:27 powerd: lldp0: LLDP PoE negotiation START
Jun 19 05:00:59 powerd: lldp0: LLDP PoE negotiation timeout !!
Jun 19 05:00:59 powerd: sending powerd message
Jun 19 05:00:59 powerd: send ipc_socket_process: 4
Jun 19 05:00:59 powerd: ps: Power mode: Full-Power, power_detection: DC_adapter(FALSE), PoE+/802.3at(30000 mWatt)
Jun 19 05:01:00 powerd: ps: End: System running on full power @ 30000 mWatt from port0
Jun 19 05:01:00 kernel: [*06/19/2022 05:01:00.8319] Set radio wifi0 power 4 antenna chain 4 15
Jun 19 05:01:00 kernel: [*06/19/2022 05:01:00.8319] Set radio wifi1 power 4 antenna chain 8 255
*************************************************************​​​​​​​***************​​​​​​​***************​​​​​​​***************
WLC will not show “full power” as LLDP communication is failed between WAP and Juniper switch, but the WAP is running on full-power.
 
**Logs from C9130AXI WAP when USB Module state is enabled and LLDP negotiation fails  (EX3400 with firmware JUNOS 18.1R3-S2.5)
C9130AXI WAP logs:
Jun 19 11:51:40 powerd: cdp0: CDP PoE negotiation START
Jun 19 11:52:40 powerd: cdp0: CDP PoE negotiation timeout !!
Jun 19 11:52:41 powerd: lldp0: LLDP PoE negotiation START
Jun 19 11:53:13 powerd: lldp0: LLDP PoE negotiation timeout !!
Jun 19 11:53:13 powerd: sending powerd message
Jun 19 11:53:13 powerd: send ipc_socket_process: 4
Jun 19 11:53:13 powerd: ps: Power mode: Degraded/Reduced Power, power_detection: DC_adapter(FALSE), PoE+/802.3at(30000 mWatt)
Jun 19 11:53:14 powerd: ps: End: System running on low power @ 30000 mWatt from port0
Jun 19 11:53:14 kernel: [*06/19/2022 11:53:14.2345] AP is in fair condition, BLE is off
Jun 19 11:53:14 kernel: [*06/19/2022 11:53:14.2345] Set radio wifi0 power 6 antenna chain 4 15
Jun 19 11:53:14 kernel: [*06/19/2022 11:53:14.2345] Set radio wifi1 power 6 antenna chain 8 255
**********************************************************************************************************

Conclusion:
LLDP POE negotiation is available on certain JUNOS version.   By default, those new Cisco WAPs will go into low power/degraded power mode if their USB module is enabled.
 
Once USB module is disabled from WLC, Cisco WAP will run on full power regardless of LLDP status. 

Modification History

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