Determine power draw of LW AP through CLI?

[coldfirex00]

Howdy,

I noticed that one of our APs is not showing Low\Medium\Full Power within our WLC.  That line is missing.  I checked the switch and it is showing no power output.  I assume this means that there is a power injector somewhere.  Is there a way to determine from the CLI of the AP how much power it is pulling?  I want to make sure that its getting full power until I have time to track it down.

Thanks!

[Leo Laohoo]

I assume this means that there is a power injector somewhere.  Is there a way to determine
 from the CLI of the AP how much power it is pulling?

If you've got a power injector, it's not the question of how much power the AP is "pulling" but how much power the injector is "pushing".  APs are smart, but not injectors.  Injectors will push whatever they've been built to push, whether the remote end client wants all of it or not.  At the end of the day, well built power end device has a tolerance limit of up to 20.0w PoE.  

If you've got a WLC, use the command show ap config general [AP Name] and scroll down to the second page under the heading "Power Type/Mode" and it will tell you if the AP is operating under full power or not.  

Just a side note:  802.11n APs have a hard code inside them to interrogate the injectors.  Although the 802.11n APs, like the 1140 and 1260, can operate at 15.4w these models (and succeeding models after that) will not work if they are NOT powered by PWR-INJ3. 

[coldfirex00]

Thanks for the reply and explanation Leo!

I checked and the WLC reports "Power injector / Normal mode".  Would that indicate full power?

[Leo Laohoo · Accepted solution]

If you've got "Power Injector" then it means that the AP is operating normally or "all radios up, all MCS up".   

Take a look at your AP.  802.11n APs such as 1140 and 1260 is 15.4w.  CleanAir APs like 3500, 3600 (without module) and 2600 are 15.4w.  802.11ac APs like 2700 and 3700 are recommended for 20.0w.  The 1600 uses less but this means you've got a special power injector, PWR-INJ4 (if memory serves me correct).

And you CANNOT and WILL NOT be able to use the old 802.11 a/b/g injectors on these APs.  They've got chips to interrogate them.  

[Abhishek Abhishek]

Step 1	Choose Configuration > Wireless > Access Points > All APs. The All APs page appears with a list of access points that are associated with the controller.
Step 2	Click the name of the access point. The AP > Edit page appears.
Step 3	Click the Advanced tab.
Step 4	In the Power Over Ethernet Settings area, select the Pre-Standard 802.3af Switches check box. Select this check box if the access point is being powered by a high-power 802.3af Cisco switch. This switch provides more than the traditional 6 Watts of power but does not support the intelligent power management (IPM) feature. Note    Unselect the Pre-standard 802.3af Switches check box if power is being provided by a power injector. This is the default value.
Step 5	Select the Power Injector State check box. Select this check box if the attached switch does not support IPM and a power injector is being used. If the attached switch supports IPM, you do not need to select this check box. The Power Injector Selection drop-down list is displayed that contains parameters that enable you to protect your switch port from an accidental overload if the power injector is inadvertently bypassed.
Step 6	From the Power Injector Selection drop-down list, choose an option to specify the desired level of protection. You can choose any one of the following three options: Installed—Examines and remembers the MAC address of the currently connected switch port and assumes that a power injector is connected. Choose this option if your network contains older Cisco 6-Watt switches and you want to avoid possible overloads by forcing a double-check of any relocated access points. If you want to configure the switch MAC address, enter the MAC address in the Injector Switch MAC Address text box. If you want the access point to find the switch MAC address, leave the Injector Switch MAC Address text box blank. Note    Each time that an access point is relocated, the MAC address of the new switch port fails to match the remembered MAC address, and the access point remains in low-power mode. You must then physically verify the existence of a power injector and reselect this option to cause the new MAC address to be remembered. Override—Allows the access point to operate in high-power mode without first verifying a matching MAC address. You can use this option if your network does not contain any older Cisco 6-W switches that could be overloaded if connected directly to a 12-W access point. The advantage of this option is that if you relocate the access point, it continues to operate in high-power mode without any further configuration. The disadvantage of this option is that if the access point is connected directly to a 6-W switch, an overload occurs.
Step 7	Click Apply.
Step 8	Click Save Configuration.