AP 1252 and Powerdsine midspan

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Jul 25th, 2008
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I have a project with AP 1252 using existing 3750 switches. As the 1252 demands more than 15,4W i am trying to user Powerdsine 7000 midspans.

The midspan is able to give up to 32W/port. I have a test setup with a couple of 1252 and a 2206 controller.

The 1252's powers up but with Poe status medium, and using only 15,4W.

How do i get them to use full power ?


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pbuch Fri, 07/25/2008 - 06:34
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I dont think that it is a configuration problem with the powerdsine product.

All ports are set to deliver max 32W.


pbuch Fri, 07/25/2008 - 11:13
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Just found this note in the controller version 5.1 manual.


When powered with a non-Cisco standard PoE switch, the 1250 series access point operates under 15.4 Watts. Even if the non-Cisco switch or midspan device is capable of providing higher power, the access point does not operate in enhanced PoE mode.

Why this limitation ?

Any workaround ?


dennischolmes Sat, 07/26/2008 - 09:58
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Powerdsine makes a dongle that you need to attach to each port a 1252 is on. This is because Cisco uses proprietary signaling to tell the midspan which PoE to use. This signaling is not 802.3at compliant and as such doesn't signal for enough power. Call your powerdsine rep and ask for the dongle. It is only about seven US dollars I believe.

pbuch Fri, 08/01/2008 - 02:23
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Thanks for your answer :-)

The 7000 series midspan should be able to use 802.3at + legacy. I have mailed Powerdsine support but havent got any answer, probably holiday :-)

Powerdsine should be able to solve this via a firmwareupgrade.


dennischolmes Fri, 08/01/2008 - 04:06
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You will still need to use the dongle I think s the signalling for the 1252 is not AT compliant and legacy only puts out 15.8 watts. That's what they told me at Networkers.

pbuch Tue, 08/05/2008 - 21:47
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Its simply because Cisco is not IEEE802.3at compliant. To bad, IEEE802.3at is not that new.

Cisco Cisco Cisco !!!! This can hobefully be solved with a firmware upgrade.


JEFFREY SESSLER Wed, 08/06/2008 - 21:51
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I just finished investigating midspans for my own 1252 deployment. At this time, there is only a single PoE vendor, and a single product within their line, that can power a 1252 at full power.

It's the Phihong POE125U-4HP 4-port POE midspan. This device can actually signal the 1252 to use full power.

pbuch Fri, 08/08/2008 - 09:21
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According to Powerdsine, they will have Cisco-Poe-plus midspans late this year.


craig.beck Sat, 08/09/2008 - 06:27
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I use a normal patch cable with the blue and brown pairs swapped over and 802.11af PoE injectors for lots of my Cisco APs without a problem.

If you use a similar cable you should be able to use your Midspan injector.

You may want to give it a try.

JEFFREY SESSLER Mon, 08/11/2008 - 10:08
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I believe the dongle simply pulls the higher power back off the ehternet to feed into the AP's power input jack.

pbuch Sat, 10/11/2008 - 00:28
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I have, and it works :-)

But it would be simpler if Cisco was folloving the standards.


dennischolmes Sat, 10/11/2008 - 04:38
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That's the problem guys. There is no true .at standard yet. There is a debate between the Cisco method of signaling and another vendors. The debate is not settled. Once ratified Cisco will jump on board as always. Of course, you know they'd like to do it Burger King style (Have it their way!)

cweinhold Wed, 10/15/2008 - 19:58
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I want to say how useful this thread has been.

A bit off topic, but Cisco is releasing the Catalyst 2975, a new stackable L2+ 48-port PoE-enabled 10/100/1000 switch at a good price point ($23k list for a pair, according to the pricelist). Does anyone know whether or not this switch will support ePoE?

pbuch Fri, 10/17/2008 - 10:22
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I havent been able to find anything about a Catalyst 2970. Would be nice to have an other choice than 2*3750E


felixdav Tue, 11/25/2008 - 20:41
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The Catalyst 2975 does not support ePoE for the 1250 APs. But it does support the new 1140 802.11n APs which are 802.3af compliant.

pbuch Wed, 11/26/2008 - 05:45
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To bad that the 2975 dosent support ePoE.

Really need a cheaper alternative to a stack 3750E.

I cant find anything about 1140, any link ?


cweinhold Wed, 11/26/2008 - 07:32
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There's a pre-launch partner data sheet at:


Here are some online refs:



AIR-LAP1142N-A-K9 $1,299 802.11a/g/n Fixed Unified AP; Int Ant; FCC Cfg

LWAPP today, Autonomous in 2009

At only 12.95 watts of power, the 1140 Series is the only platform to combine the power of dual-radio 802.11n with the efficiency of standard PoE. Additionally, the 1140 Series is designed to operate more efficiently during off-peak hours when fewer clients are connected to the access point.


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