Trouble using Cisco 1231 AP's with Dell PowerConnect 3448P

Hi,

I have not come across this problem before. Does the Cisco AP ever get power or does it happen intermittantly? With the AP connected can you type "show power inline" and post the output. Are there any visible lights on the AP or is completely dead when connected to the switch? Try disabling spanning-tree on the switchport connected to the AP to see if this makes any difference.


Thanks

The Cisco AP never seems to get power.  The lights on the AP never even flicker.  When I plug the AP into a Cisco powered switch it immediately springs to life.  Dell support has told me that the power consumption on the AP is 13W and that the powered switch is designed to send 12.95W, but we do have the additional power pack which should give us 15.4 W.  Here is the result of the show command:

show poer [D [Dwer inline

Power :On
Nominal Power :806 Watts
consumedPower :0 Watts (0%)
Usage Threshold :95
Traps : Disabled

 Port    Powered Device    State      Status    Priority   Class 
-------- ---------------- ---------- ---------- ---------- -------
  e1                        Auto    Searching     low     class0 
  e2                        Auto    Searching     low     class0 
  e3                        Auto    Searching     low     class0 
  e4                        Auto    Searching     low     class0 
  e5                        Auto    Searching     low     class0 
  e6                        Auto    Searching     low     class0 
  e7                        Auto    Searching     low     class0 
  e8                        Auto    Searching     low     class0 
  e9                        Auto    Searching     low     class0 
 e10                        Auto    Searching     low     class0 
 e11                        Auto    Searching     low     class0 
 e12                        Auto    Searching     low     class0 
 e13                        Auto    Searching     low     class0 
 e14                        Auto    Searching     low     class0 
 e15                        Auto    Searching     low     class0 
 e16                        Auto    Searching     low     class0 
 e17                        Auto    Searching     low     class0 
 e18                        Auto    Searching     low     class0 
 e19                        Auto    Searching     low     class1 
 e20                        Auto    Searching     low     class0 
 e21                        Auto    Searching     low     class0 
 e22                        Auto    Searching     low     class0 
 e24                        Auto    Searching     low     class0 
 e25                        Auto    Searching     low     class0 
 e26                        Auto    Searching     low     class0 
 e27                        Auto    Searching     low     class0 
 e28                        Auto    Searching     low     class0 
 e29                        Auto    Searching     low     class0 
 e30                        Auto    Searching     low     class0 
 e31                        Auto    Searching     low     class0 
 e32                        Auto    Searching     low     class0 
 e33                        Auto    Searching     low     class0 
 e34                        Auto    Searching     low     class0 
 e35                        Auto    Searching     low     class0 
 e36                        Auto    Searching     low     class0 
 e37                        Auto    Searching     low     class0 
 e38                        Auto    Searching     low     class0 
 e39                        Auto    Searching     low     class0 
 e40                        Auto    Searching     low     class0 
 e41                        Auto    Searching     low     class0 
 e42                        Auto    Searching     low     class0 
 e43                        Auto    Searching     low     class0 
 e44                        Auto    Searching     low     class0 
 e46                        Auto    Searching     low     class0 
 e47                        Auto    Searching     low     class0 
 e48                        Auto    Searching     low     class0 

Hi,

I am looking into this for you. I found an article on the Cisco website which is interesting.

http://www.cisco.com/en/US/products/hw/wireless/ps430/prod_technical_reference09186a008039e541.html

Basically it is saying that the 1200 series AP was designed pre-standard (prior to 802.3af ratification), and requires a PowerDSine midspan to operate. Now, the PC3424P does include 2 x PowerDsine chips and should detect pre-standard equipment so this should work.

I do not think this problem has anything to do with power consumption, we can provide 12.95W or 14.5W with the EPS-470 and according to Cisco the 1200AP with both A and G radios enabled will only consume 12.36W. Let me see what else I can find out and I will get back to you.


Regards

Hi,

Ok, I know why this has not been working. Basically because it is pre-standard it is using different pairs on the CAT5 cable to receive power, in order for it to work correctly on a ratified switch you must switch the polarity, this is done by using a specific cable. The part number you need is PD-PS-401/Cisco.

Info from Cisco below:-

Non-Cisco Power Options
PowerDsine Midspan Products

Most Cisco Aironet access points use inline PoE from power injectors or Cisco powered EtherSwitches, but the Cisco Aironet 350, 1100, and 1200 series access points do not directly support IEEE 802.3af power sources. These access points were designed before the IEEE 802.3af power standard was ratified and must use third party products such as PowerDsine to support IEEE 802.3af power sources.

PowerDsine offers midspan power products that allow customers to deploy a combination of
IEEE 802.3af powered devices and non-IEEE 802.3af powered devices such as the Cisco Aironet 1120 and 1121 access points and the Cisco Aironet 350 and 1200 series access points.

PowerDsine's 6006 and 6012 Inline Power Midspan (residing between the Ethernet switch and the access point) supplies power to the access point using unused pairs of wires within the Category 5 cable. This is similar to the capacitive power detection method used by Cisco Aironet power injectors, but the power polarity is reversed. The PowerDsine products apply a positive voltage on pairs 4 and 5 and a negative voltage on pairs 7 and 8. Cisco Aironet power injectors apply a positive voltage on pairs 7 and 8 and a negative voltage on pairs 4 and 5.

PowerDsine 6006 and 6012 products comply with the IEEE 802.3af standard, but also supports a second detection method. These products first attempt to detect powered devices using the IEEE 802.3af resistive power detection method, then if a powered device is not detected, they switch to capacitive power detection mode. When using capacitive power detection, these products can successfully power Cisco access points provided the power pins are switched to the correct polarity. The polarity reversal is accomplished using a PowerDsine adapter cable referred to as a prestandard passive splitter.


Hope this helps,

Regards

Hi Adam,

Thanks for your help on this.  It looks like this definitely is our issue.