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kscrib's avatar
kscrib
Tutor
Mar 07, 2020
Solved

WAC740 AF Power (Radio Off) error on WC7500

I have a WAC740 connected to a Cisco 2960S (POE+ / 803.2at) switch with 740w of POE+ power.  I have tried this with the WAC740 being the ONLY device connected to the 2960S switch and had the same pro...
  • kscrib's avatar
    kscrib
    Mar 12, 2020

    OK - disregard all the commands in the 2nd post.

    The problem is that by default the Cisco 2960s switch had LLDP disabled and was running the Cisco proprietary CDP. CDP does not properly communicate with non-Cisco devices.  LLDP is used to communicate things like power negotiation between the PSE (Power Source - aka switch) and PD (Power Device - aka WAC740 AP).  The fix was a couple of simple commands:

    Cisco2960s# configure terminal

    Configuring from terminal, memory, or network [terminal]? Enter configuration commands, one per line. End with CNTL/Z.

    Cisco2960s(config)# no run cdp
    Cisco2960s(config)# lldp run
    Cisco2960s(config)# end
    Cisco2960s# copy running-config startup-config

     

    That is all it takes to solve it!

     

    You can see below where LLPD does the power negotiation:

     

    Cisco2960s# show power inline gi1/0/41 detail
    Interface: Gi1/0/41
    Inline Power Mode: auto
    Operational status: on
    Device Detected: no
    Device Type: Ieee PD
    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: 11.4
    Maximum Power drawn by the device since powered on: 13.7

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

    Power Negotiation Used: IEEE 802.3at LLDP
    LLDP Power Negotiation --Sent to PD--         --Rcvd from PD--
    Power Type:                      Type 2 PSE             Type 2 PD
    Power Source:                   Primary                   PSE
    Power Priority:                   low                          critical
    Requested Power(W):       25.5                         25.5
    Allocated Power(W):         25.5                         25.5

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

kscrib's avatar
kscrib
Tutor
Mar 12, 2020

I have gotten further in this but have not gotten to resolution.  I now know that the WAC740 identifies as a Class 4 POE device.  The Cisco switch expects a two step negotiation on power.   The AP powers up (as 802.3af, less than 15w), updates its firmware, communictes with the WC7500 (required for WAC740s) and later turns on the 2.4 and 5.0 GHz radios.  Some where in the radio conversation the AP is requesting more power.  I can see in the switch logs that the AP never requests or uses more than 15 watts.  Even though I have configured the switch port to allocate 30w to the port.

config terminal
Configuring from terminal, memory, or network [terminal]? Enter configuration commands, one per line. End with CNTL/Z.
c2960x-48fpd-l-0(config)# int gi1/0/47
c2960x-48fpd-l-0(config-if)# no cdp enable
c2960x-48fpd-l-0(config-if)# no power inline auto
c2960x-48fpd-l-0(config-if)# power inline static max 30000
c2960x-48fpd-l-0(config-if)# power inline port 2x-mode
c2960x-48fpd-l-0(config-if)# power inline police action log
c2960x-48fpd-l-0(config-if)# description WAC740
c2960x-48fpd-l-0(config-if)# shutdown
c2960x-48fpd-l-0(config-if)# no shutdown
c2960x-48fpd-l-0(config-if)# end

 

Even though I have set the port 30,000 (30w) and allow a power request surge of upto 60000 (60w) via "port 2x-mode" the switch still shuts off the wifi radio and goes into an "radio off" status.

The problem lies somewhere in the handshake between the AP and the switch when they are negotiating POE wattage.  Any Cisco studs out here who an get me over the hump?  I have to be close.

kscrib's avatar
kscrib
Tutor
Mar 12, 2020

OK - disregard all the commands in the 2nd post.

The problem is that by default the Cisco 2960s switch had LLDP disabled and was running the Cisco proprietary CDP. CDP does not properly communicate with non-Cisco devices.  LLDP is used to communicate things like power negotiation between the PSE (Power Source - aka switch) and PD (Power Device - aka WAC740 AP).  The fix was a couple of simple commands:

Cisco2960s# configure terminal

Configuring from terminal, memory, or network [terminal]? Enter configuration commands, one per line. End with CNTL/Z.

Cisco2960s(config)# no run cdp
Cisco2960s(config)# lldp run
Cisco2960s(config)# end
Cisco2960s# copy running-config startup-config

 

That is all it takes to solve it!

 

You can see below where LLPD does the power negotiation:

 

Cisco2960s# show power inline gi1/0/41 detail
Interface: Gi1/0/41
Inline Power Mode: auto
Operational status: on
Device Detected: no
Device Type: Ieee PD
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: 11.4
Maximum Power drawn by the device since powered on: 13.7

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

Power Negotiation Used: IEEE 802.3at LLDP
LLDP Power Negotiation --Sent to PD--         --Rcvd from PD--
Power Type:                      Type 2 PSE             Type 2 PD
Power Source:                   Primary                   PSE
Power Priority:                   low                          critical
Requested Power(W):       25.5                         25.5
Allocated Power(W):         25.5                         25.5

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