Powering Unify UAP-AC-IW

sajunky

Honorary Master
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Nov 1, 2010
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11,680
#1
It looks like this device do not conform to the PoE standard 802.3af nor 802.3at (PoE+).
It is also why most of the 48V passive sources do not work with this AP.

Which PoE router, switch or injector do you use with UAP-AC-IW?
 

sajunky

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Nov 1, 2010
Messages
11,680
#3
Thanks for reply. Unfortunately a rack mounted 19" do not fit in the wall cabinet. I have to chose something from desktop size offers. It limits my choice dramatically.

I looked at the various versions of the specification of this AP, it looks it is even orphaned from the other Ubiquity offerings. One official source says it is compliant with 802.3af/A, which I read it is limited to the "Alternative A" configuration, while Wikipedia says:
The PSE (power sourcing equipment), not the PD (powered device), decides whether power mode A or B shall be used. PDs that implement only Mode A or Mode B are disallowed by the standard.
It seems to be a reason for compatibility problem with most of PoE sources. Passive devices typically use Alternative Mode 'B' and active power sources are allowed to support only 'A' or 'B' as they wish. In other words I have to find power source that is using specifically Alternative Mode 'A'.

According to some Internet sources TP-Link TL-PoE150S PoE injector will work with Ubiquity UAP-AC-IW. It is inexpensive, I will probably find it locally below R200, so there is a solution. However I need at least 3 PoE ports, so getting integrated ports in the switch is more convenient option.

Looking for TP-Link products at first place due to the presence of Uniterm Direct reps on this forum, so I can get the best advice. There is a nice 8 port switch model TL108PE or TL-SG1008P with 4 PoE 802.3af compliant ports. Documentation of TL-SG1008P says it is using pins 1,2 for minus and pins 3,6 for plus. Pin layout is the same as an Alternative Mode A, but actually polarity is reversed! Does it matter and safe? When I use cross-over cable, polarity should be reversed anyway.

A similar device is Netgear GS308P, but I couldn't get any details specific to PoE implementation.
 
Last edited:

Rickster

EVGA Fanatic
Joined
Jul 31, 2012
Messages
15,563
#5
IMPORTANT: The UAP-AC-IW requires a UniFi Switch
with PoE for power. Passive PoE adapters are not
recommended



Screen Shot 2018-01-12 at 09.49.53.png
 

sajunky

Honorary Master
Joined
Nov 1, 2010
Messages
11,680
#9
Not sure that one will work, it's not 802.3at PoE+ just 802.3at (Please correct me if I am wrong)
You are absolutely right, but let me explain it. This AP is negotiating Class 4 power level, as it needs total 19W (7W for its own use and 13W for the external PoE powered device (which can be plugged-in to UAP-AC-IW). As power level Class 4 do not exists in 802.2af, they say that 802.3at is required (PoE+ is a marketting term for 802.3at). However it is foolishly wrong, as power level Class 4 is optional in the 802.3at specification. To be absolutely correct they should say their requirement is 802.3at Type 2 power source.

When there is no external PoE device connected to the AP, 802.3af power source is sufficient for AP operation. I saw an official statement on the Ubiquity forum confirming this.

The only problem seems that this AP do not comply with 802.3af nor 802.3at specification, as it is unable to switch between 802.3af Alternate Mode A and Alternate Mode B as required per af/at standards.
 
Last edited:

irBosOtter

Expert Member
Joined
Feb 14, 2014
Messages
1,186
#10
You are absolutely right, but let me explain it. This AP is negotiating Class 4 power level, as it needs total 19W (7W for its own use and 13W for the external PoE powered device (which can be plugged-in to UAP-AC-IW). As power level Class 4 do not exists in 802.2af, they say that 802.3at is required (PoE+ is a marketting term for 802.3at). However it is foolishly wrong, as power level Class 4 is optional in the 802.3at specification. To be absolutely correct they should say their requirement is 802.3at Type 2 power source.

When there is no external PoE device connected to the AP, 802.3af power source is sufficient for AP operation. I saw an official statement on the Ubiquity forum confirming this.

The only problem seems that this AP do not comply with 802.3af nor 802.3at specification, as it is unable to switch bewteen 802.3af Alternate Mode A and Alternate Mode B as required per af/at standards.
Cool thanks, think a lot of people get confused with the at, at+ and at type 2
 
Last edited:

aybbleek

Expert Member
Joined
Sep 9, 2013
Messages
1,384
#11
You are absolutely right, but let me explain it. This AP is negotiating Class 4 power level, as it needs total 19W (7W for its own use and 13W for the external PoE powered device (which can be plugged-in to UAP-AC-IW). As power level Class 4 do not exists in 802.2af, they say that 802.3at is required (PoE+ is a marketting term for 802.3at). However it is foolishly wrong, as power level Class 4 is optional in the 802.3at specification. To be absolutely correct they should say their requirement is 802.3at Type 2 power source.

When there is no external PoE device connected to the AP, 802.3af power source is sufficient for AP operation. I saw an official statement on the Ubiquity forum confirming this.

The only problem seems that this AP do not comply with 802.3af nor 802.3at specification, as it is unable to switch bewteen 802.3af Alternate Mode A and Alternate Mode B as required per af/at standards.
Yeah I came to the same conclusion with this Uniquiti model. Pain the @rse to be honest. Went through 3 HP switches before I realized the APs were the problem
 

phaktza

Executive Member
Joined
Jun 29, 2008
Messages
6,184
#17
Thanks for reply. Unfortunately a rack mounted 19" do not fit in the wall cabinet. I have to chose something from desktop size offers. It limits my choice dramatically.

I looked at the various versions of the specification of this AP, it looks it is even orphaned from the other Ubiquity offerings. One official source says it is compliant with 802.3af/A, which I read it is limited to the "Alternative A" configuration, while Wikipedia says:

It seems to be a reason for compatibility problem with most of PoE sources. Passive devices typically use Alternative Mode 'B' and active power sources are allowed to support only 'A' or 'B' as they wish. In other words I have to find power source that is using specifically Alternative Mode 'A'.

According to some Internet sources TP-Link TL-PoE150S PoE injector will work with Ubiquity UAP-AC-IW. It is inexpensive, I will probably find it locally below R200, so there is a solution. However I need at least 3 PoE ports, so getting integrated ports in the switch is more convenient option.

Looking for TP-Link products at first place due to the presence of Uniterm Direct reps on this forum, so I can get the best advice. There is a nice 8 port switch model TL108PE or TL-SG1008P with 4 PoE 802.3af compliant ports. Documentation of TL-SG1008P says it is using pins 1,2 for minus and pins 3,6 for plus. Pin layout is the same as an Alternative Mode A, but actually polarity is reversed! Does it matter and safe? When I use cross-over cable, polarity should be reversed anyway.

A similar device is Netgear GS308P, but I couldn't get any details specific to PoE implementation.
If you want something smaller:

https://www.zyxel.com/uk/en/products_services/gs1200_series.shtml
 

sajunky

Honorary Master
Joined
Nov 1, 2010
Messages
11,680
#18
It looks like Ubiquity access points UAP-AC-Lite and UAP-AC-LR received upgrade last year from the passive 24V: https://community.ubnt.com/t5/UniFi...ting-802-3af-Pic-attached/m-p/1934259#M227992
R4V3R
SuperUser
Re: AP-AC-LR now supporting 802.3af? Pic attached
Options
‎05-17-2017 09:42 PM

Ubiquiti hasn't denied this. It's a small upgrade and was done kinda silently, yes, but that's because it has no downsides. Newer units of UAP-AC-Lite and UAP-AC-LR should all support 802.3af/Mode A as well as the previously supported 24v "passive" PoE while costing the exact same price.
If the box has that sticker, then the AP inside will support both PoE in methods, and if the sticker isn't there, well, I think you get it.
Se the highlighted part "802.3af/Mode A". It means they do not compliy with af/at standard. They may work with some 802.3af PoE sources, and will fail with many other which use Mode B wiring. The same incompatiblity as UAP-AP-IW and IW-PRO access points already have. Be warned.
 
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