802.3af POE confusion

Does anyone know the 15.4W output power per user port in the current 802.3af is the min. or max.? I've seen conflicting info on different vendor's spec sheet. If it's the max., then why are some "802.3af" injectors outputting as much as 1A.

it is the max. 1 A POE can power multiple equipments.
yytellmey

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Cisco 1252s with regular 802.3af PoE switches - what are the impacts?

Does anyone have any real-life experience with deploying the 1252s on regular 802.3af PoE switches? I have a few 1252s one some 3560 PoE ports and the show up with "low power" alarms.
I am wondering what the real world impact is with this scenario. The 1252s have both 2.4 Ghz and 5.0 Ghz radios in them and I have HT enabled on the controller.
I'm wondering what capabilities I am losing by running on 802.3af power besides the annoyance of the alarms.
Thanks in advance!

Sorry in advance for the book I have just written.
I have three 1252s on 75 feet of Cat5e cable running to a 3560 PoE switch. Sometimes, but not always, I see a low power alarm on the access point(s). This is in a small building that is built like a fortress so the RF environment is somewhat challenging. I am watching WCS closely and see all three 2.4 GHz radios powered all the way up to power level 1. I notice that two of the 5GHz radios are on power level 1, and one is on level 3. I thought that RRM would not power anything down until you had at least four access points as RF neighbors. I believe I read that in a Ciscopress book and it seems to be true everywhere in our network when I look at buildings with 3 or less WAPs.
The building in question does not have any other buildings close by with any 5GHz radios in operation - or at least I didn't see any when I did the survey.
I'm wondering if the power setting of the radios is also related to the length of the Cat5e cabling. Seems to me a shorter run would have less resistance than longer runs, allowing the radio to have more power.
My main concern is not this building in question, since we went for coverage and not client density in the design. We several other buildings on the radar, all libraries, which are going to be both RF challenging (bookshelves, furniture, cubicles, cubbies) and client-density challenged. These buildings have hundreds of WLAN clients in them at times - and I mean devices, not just people.
Someone else told me (reputable source) that channel bonding is not an option when on 802.3af power. Makes sense, actually. I would never even think of bonding in the 2.4 GHz range for obvious reasons, but up in the 5GHz range it is a definate possibility in these buildings. Seems to be that we might be shooting ourselves in the foot by not using 802.3at power in these buildings.
If channel bonding is disabled and the upper two MCS rates (using 800ns guard interval) of 117 and 130 are disabled, then I'm looking at maximum MCS rate of 104 Mbit/s compared to 270 Mbit/s with 802.3at with channels bonded in the 5GHz range.

What happens if 3700 with WSSI module is connected to 802.3af PoE port?

I know that the 3700 itself will drop to 3x4 MIMO if it only gets 15.4W of power (takes 16.8 with 4x4). If I add in a WSSI module, I know that is not enough power to run the WSSI module. We'd like to deploy our APs with the module installed and light up WSSI only as we get 802.3at power available. What I don't know is if the AP will light up as 3x4 with WSSI disabled, or if the AP will just completely fail. I should get a chance to test this soon, but if you happen to know, please tell!
Thanks!
Gary Hahn

If you have enough power to the AP, you can look at the GUI and under the main screen under Access Point Summary, you will see Dual-Band Radios... the WSSI or WSM will show up there.
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Scotty

Aironet 1100 / 802.3af Power Over Ethernet (POE) Support

I was under the impression that the Aironet 1100 supports 802.3af POE. I purchased a NetGear FS108P POE switch, however, when I plug in the 1100, it does not receive any power.
I have seen references in the documentation to a Cisco inline power injector and a Cisco Catalyst switch that can provide POE to the 1100 and maybe they will work, however, will the 1100 only work with those devices?? If so, it would seem that the 1100 really doesn't support the 802.3af standard and that Cisco's implementation of POE is proprietary.
Any input would be appreciated.
Thanks,
Michael

Hi Michael,
As you have discovered (unfortunately) is that the 1100 only supports Cisco Pre-standard PoE :( Have a look;
Single 802.11g radio offering 54 Mbps of capacity
2.4 GHz integrated diversity dipole antennas
Available in an autonomous version only
16 MB of memory with 8 MB of storage
Operating temperature range of 32 to 104?F (0 to 40?C)
**Inline power support (Cisco pre-standard)**
From this doc;
http://www.cisco.com/en/US/products/hw/wireless/ps4570/prod_brochure0900aecd8035a015.html
The good news is that either of the options you listed will work just fine. I would go for the power injector probably just for neatness sake.
POWERING OPTIONS
The Cisco Aironet 1100 Series can be powered either locally using the AC-DC power adapter, or over the Ethernet cable when coupled with a device capable of delivering in-line power, such as an in-line power-capable Cisco Catalyst? switch, Catalyst in-line power patch panel, or Cisco Aironet Power Injector.
The AC-DC power adapter is included with the access point and can also be ordered as a spare part. The Cisco Aironet Power Injector can either be configured to the order or can be ordered separately.
You can use either;
AIR-PWR-A= Cisco Aironet Power Supply-Input 110-240VAC, Output 48VDC, 380 mA-for 1100 and 1200 Series
AIR-PWRINJ3= Cisco Aironet Power Injector for the 1100 and 1200 Series Access Points
From this doc;
http://www.cisco.com/en/US/products/hw/wireless/ps4570/products_data_sheet0900aecd8045690f.html
Hope this helps! And good luck!
Rob
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Clarifying 1250 802.3af operation

When installing 1250 AP on standard 802.3af PoE, according to the following: http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps6973/ps8382/product_data_sheet0900aecd806b7c5c.html :
operation will be limited to a single transmitter per radio with maximum PHY data rates of 150 Mbps instead of 300 Mbps per radio
Just verifying that this means a "single" spatial stream, per Radio. In other words, the radio requires less power due to lowering the amount of spatial streams on both 2.4 and 5GHz radios. This effectively changes the spec. from a "2x3" to a "1x3" on each radio. 1 transmitter and 3 recievers.
Reducing the number of spatial streams (or "transmitters" as described in that document) reduces both overall power draw as well as throughput capability.
Is that technically accurate?

That is correct. The work around was either the AP having to reduce the transmission like you mentioned or a radio had to be removed.
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PoE standard (cisco ILP vs 802.3af)

I have CCNP switch official guide book, page 306 says below.
For cisco ILP, inline power is provided over data pairs 2 and 3 (RJ45 1,2 and 3,6)
For 802.3af power can be supplied in the same fashion (1 2 3 6) or over paris 1 and 4 (RJ45 4,5 and 7,8)
Can you give me when those bold option is used in terms of PoE?
Thanks.

I believe the 802.3af standard actually allows both pinout configurations.They are known as Mode A and Mode B. Mode A uses the data pairs while Mode B uses the "spare" pairs. I have always been under the impression that Mode A would be what one would find on devices that terminate a connection. For example, a Cisco Catalyst switch that provides 802.3af power will use the Data Tx/Rx pairs (pins 1,2,3,6). Further, my belief is that Mode B would be used by "mid-span" devices that insert power. For example, in-line power patch panels or in-line power injectors. These panels use the "spare" pairs to carry DC power (pins 4,5,7,8).
The equipment that provides the power (i.e. the power sourcing equipment) determines which Mode (i.e. pins) is used. The powered device that is 802.3af compliant must be capable of supporting both modes.
Here is a quick reference chart:
https://supportforums.cisco.com/docs/DOC-10259
The chart doesn't directly answer your question, but you may find it handy as you are getting a feel for the material.
HTH.
Regards,
Bill
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SF-302-08P will not power 802.3af/at device

I'm trying to power a Ruckus 7982 Access point using a Small Business SF-302-08P switch. Ruckus claims the AP is 802.3af and 802.3at compatible. The switch reports an overload.
#sh power inline fast 5
Port      Powered Device         State          Status    Priority   Class
fa5             2                 Auto          Fault       low     class0
Time range:
Power limit: 15.400W
Port Status:               Port is off - Overload state
Overload Counter:          23
Short Counter:             0
Denied Counter:            0
Absent Counter:            0
Invalid Signature Counter: 0
Here's what Ruckus' description of the PoE behavior of the 7982:
The 7982 advertises itself as a Class 4 PoE device (as do other enterprise class 3-stream APs), which is compatible with 802.3af and 802.3at switches.
802.3af switches re-classify a device with this behavior as 802.3af Class 0 (15.4W), and the vast majority of 802.3at switches classify it as 802.3at Type 1 (15.4W).
This implementation is intentional as it maintains compatibility with both 802.3af and 802.3at switches, and allows the 7982 to support full 802.3at power (>15.4W with a future firmware upgrade to support LLDP, if required).
Seems to me it should work. I updated to 1.3.0.62 - no change.

Hello,
     I didn't fully finish reading this post but read enough were I feel like this should be able to help you out.
https://supportforums.cisco.com/thread/2165089
So pretty much this should work just fine though since the switch can for sure handle 15.4Ws. May be some configurations you need to check our or some changes you may need to make.
Hope that helps you out.
Thanks,
Clayton Sill.

Is AIR-PWRINJ4 compatible to any 802.3af standard device?

Hi all,
today i have a special request to supportforum.
i'd like to know if AIR-PWRINJ4 supports any "non Cisco" 802.af device.
Is there any data sheet available for AIR-PWRINJ4?
Thanks for let me know.
Dieter

Hello.
Following this topic, I'd like to ask for help :-)
I have a CP-6921 and the switch where the phone is connected there is no PoE.
I've requested a Power Injector (CP-PWR-CUBE3) to sales team, but the delivery time is too far.
Meanwhile this, I'm wondering, can I attach the phone in a AIR-PWRINJ4= ?
I have one (spare).
It's 802.3af compliant, but in the part there is a label which contain:
OUTPUT: 56V ---- 0.55A
So, I got this doubt, is there any risk of damage the phone?
Any help will be welcome.
Thank you in advance.
Best

Extreme 802.11n support for POE 802.3af?

Can anyone confirm if the new (current) generation Airport Extreme 802.11n supports PoE installation? There was a special -- also called education -- version of the previous generation Extreme based station for POE installation.
thanks.
* Nevermind, found previous posts!

jheiliger, Welcome to the discussion area!
The new square 802.11b/g/n AirPort Extreme base station (AEBS) apparently does NOT support POE (Power over Ethernet).

Catalyst Express 500 Series WS-CE500-24PC PoE

Inline power (PoE)
Can some one confirm PoE Spec's and a little confused reading the spe'c
the spec say
●All 24 PoE ports on the Cisco Catalyst Express 500-24PC can supply up to 15.4W
(IEEE 802.3af standard maximum) of power over Category 5 cable, for a total of 370W
of inline power.
● Both the IEEE 802.3af PoE standard and Cisco prestandard inline power are supported
I have cisco 7940G witch are Prestandard so this switch will power the Phones on PoE ?
does not say it will supply PoE for Prestandard Phones just say its Supported
Thanks

Hi Colin,
Yes, the switch will power prestandard 7940s. Specs state it works on both 802af and cisco prestandard poe.
Best,
David
Please rate helpful posts and identify correct answers.

PoE optimizing

Hi
I have a 2960s PoE Switch that powers some 2702 Access Points.
Each AP has 15,4 watts allocated:
show power inline
Gi1/0/23 auto   on         15.4    AIR-CAP2702I-E-K9   4     30.0
But the effective power consumption is much less (between 6,3 and 6,8 watts)
show power inline Police
Gi1/0/23 auto   on         errdisable ok         15.4   6.3
In summary the power Budget of the Switch is
Module   Available     Used     Remaining
          (Watts)     (Watts)    (Watts)
1           370.0      338.8        31.2
But the sum of operational power is only 144 watts
When I reduce the power per port to e.g. 12 watts
power inline consumption 12000
the Access Point disables its Radios because of low power.
Is there a way to optimize PoE for these Access Points?
Thanks in advance
Thomas

These APs can work off or regular PoE 15.4w but will be in a 3x3 not 3x4. The power draw is defined in the datasheet.
Powering options
● 802.3at PoE+
● Enhanced PoE
● Cisco AP2700 power injectors (AIR-PWRINJ4=)
● Cisco AP2700 local power supply (AIR-PWR-B=)
Note: If 802.3af PoE is the source of power, the access point will dynamically shift from 3x4 to 3x3 and come up underPoE.

SLM224G4PS Radius and PoE

Hi,
First I'd like to know if there is a white paper on how to setup a win2003 radius server in order to use this switch 802.1x auth feature. Thanks A LOT if I can get help on this.
Second:
In this switch Web page spec I read:
Provides IEEE 802.3af PoE power to IP phones, surveillance cameras, and Acess Points. Up to 12 ports (port 1 - 6 and port 13 - 18) PoE with total power budget of 100 W.
... and in its PDF Datasheet i read:
Provides IEEE 802.3af PoE power to IP phones, surveillance cameras, and Access Points. Up to 24 ports (port 1-6, port 13- 18) PoE with total power budget of 180W.
Which of these statements are correct? I need / want a switch with 24x 100Mbps PoE ports. Do I get that with this switch, and if not, which (budget) model do I choose to get that?
Thanks a lot for comments on these issues.
regards
Tor

OK, I realize that only half of the actual port count is supported as of PoE. But I cannot understand why LS has designed it with such a flaw.
However, I hope someone has a comment or tip on my other issue. where do I find a good howtor or white paper on setting up a w2003 ias/radius server so I can connect my 802.1x switches to it...
rgds
Tor

Poe881 Router and Cisco Inline Power (pre-standard PoE)

I have a number of 881 Routers and 79x0 IP Phones. These phones use "Cisco Inline Power", aka "pre-standard PoE". In other words, they are not compatible with standard 802.3af PoE.
It would be possible for me to install a daughtercard and DC adapter in the 881 routers and provide PoE to two of the ethernet ports. My question is whether the 881 (when equipped for PoE) will support Cisco Inline Power, or if it will only support 802.3af.
For reference, the 200 and 300 series Small Business switches support these phones with a software upgrade. See this link: https://supportforums.cisco.com/document/71841/200-and-300-switches-now-supports-cisco-pre-standard-poe-legacy-poe
Many thanks,
Tom

My question is whether the 881 (when equipped for PoE) will support Cisco Inline Power, or if it will only support 802.3af.
Hi Tom,
I don't have an 880 but I have a large fleet of 890 and all of them have PoE and I know these 890 support 802.3af easily.

SD208P PoE and Pre-Standard Cisco IP Phones (eg. 7960)

Well, I've been learning the eccentricities of Cisco's product lines the hard way! Here's my situation:
I've taken over for an office that has a hosted Cisco IP phone system using a variety of what seem to be older Cisco phones (the one at my desk is a 7960) these are normally powered by the PoE that gets delivered by some Cisco Catalyst 3750X switches. Our office has grown to the point where we've had to place a few people into some semi-jury rigged seats in areas with limited network drops. As a result I need to do something creative to get phones over there.
I first went out and purchased a small 8 port switch with 4 PoE ports on it from a competitor and this was where I discovered that the models of Cisco phones I had needed something generally referred to as Cisco Pre-Standard PoE (or some variation on that theme). I returned the switch and after doing some research decided to buy a Cisco SD208P switch, which a few messages out on the Interwebs led me to believe should be able to power the switch (possibly a firmware upgrade would be needed).
So I got the switch today, and plugged my phone into it and... nothing. No signs of life on the phone. (And nothing as simple as plugging it into one of the non-PoE ports on the switch). I went online to try and find a firmware update, and couldn't find anything. It's also an unmanaged switch, so I'm not even sure how I'd update firmware on it if I wanted to (and there's nothing in the manual).
I went back and double-checked some of the sources that may have led me to believe that this would work and I found what turned out to mostly be people recommending this as a possible option, but not strictly saying it worked for them. I found one person saying it worked for some Cisco phones, but he didn't specifically say they were prestandard ones. Lastly, there is mention of 200 and 300 series switches being firmware upgradable to support prestandard PoE, but from looking around Cisco's site I'm not 100% sure that this switch is actually part of the 200 series despite the number in the name. It seems to show up in a Small Business Unmanaged Switch category online rather than in any proper series.
So, the question is - have I just missed something somewhere? Is there any hope for me? Or do I have to send this back and go for something else? If so, what's recommended? Perferably something in that price range or we might just give in and... gasp... buy power supplies.
Thanks,
Chris.

Hi Chris,
The SD208P is an unmanaged switch that does not have any web interface and you will not be able to upgrade firmwares on this switch. The unmanaged switch that you have gotten will only support 802.3af POE standard and does not support the Cisco pre-standard. Also, you did mention the 200 and 300 series switches which are managed switches and with the latest firmware of 1.1.2.0, you will be able to power up your 7960 phones. The models are called SF200, SF300, SG200, and SG300. Please make sure to get the models with the letter "P" for POE. For example, you can get the SF300-24P. I hope this information is helpful.
Thanks,
Brian Ng

SG200-08 (SLM2008T) - is there a PD power option?

The original SLM2008 had the option to be powered via 802.3af PoE-PD on port 1.
Is this option still available on the newer SLM2008T? I cannot find it mentioned in any of the Cisco documentation.
Some on-line suppliers' websites state that it is an option but I'm not sure if they simply haven't updated their information to reflect the new model.
Happy New Year to all.

I'm just closing this by saying I've now obtained one of these switches & it does indeed have the PD option.
Thanks again to Robert.
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802.3af POE confusion

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