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New Member

Cisco AP 3700 PoE

Assuming we have a 802.3at (30W) capable Switch but we don’t need 802.11ac on the Cisco 3700 AP…can we disable the 802.11ac functionality ?

I also think that without disabling the 802.11ac functionality on the 3700 AP the AP/Switch will negotiate automatically on 802.3at (~20W) ? maybe i could set a max poe for 15.4W on the switch (Cisco 3650) so the AP can’t get more power... ?

Thanks for any informations!

Manuel

Everyone's tags (7)
32 REPLIES
Hall of Fame Super Silver

Re: Cisco AP 3700 PoE

You can disable the AC radio if you wish but that's not going to lower the power. The 3700, doesn't require the power that the 3600's require with an AC module. I would keep the AC enabled in the 3700 and let PoE negotiate power to be safe. You may have more issues in the long run if you set the power to a limit and the AP tries to negotiate power even though the switch is set.

If you still want to set the power, I suggest you just test it out on the switch you will be using. This way you can see what the AP negotiates at and maybe you are fine with it.

Sent from Cisco Technical Support iPhone App

-Scott
*** Please rate helpful posts ***
New Member

Re: Cisco AP 3700 PoE

Thanks Scott, but then i will have >15.4W per Port (arround 20W)... or not?

Hall of Fame Super Silver

Cisco AP 3700 PoE

This should help:

Power draw

• AP3700: 15W

Note: When deployed using a Power over Ethernet (PoE) specification, the power drawn from the power sourcing equipment will be higher by some amount dependent on the length of the interconnecting cable.

Thanks,


Scott

Help out other by using the rating system and marking answered questions as "Answered"

-Scott
*** Please rate helpful posts ***
Hall of Fame Super Gold

Cisco AP 3700 PoE

At 20.0w, the 3700 will have 4x4:3.

At 15.4w, the 3700 will operate at 3x3:2.

So it doensn't matter if you turn off 802.11ac.  It play with the power input properties of the switch and force the AP to operate at 15.4w then it will severely impact not just 802.11ac but 802.11n as well.

New Member

Re: Cisco AP 3700 PoE

Dear All,

Thanks for your input. According to the Datasheet the Cisco AP 3700 needs 15W. Does anybody know how much Wattage the Access Point is requiring at the Switchport (PSE) inclusive Link Loss (100 meter cable). I think this is arround 18W correct?

Regards

Manuel

VIP Purple

Re: Cisco AP 3700 PoE

As Leo said, it is 20W at the switch end (PSE). AP itself required ~18W to have full 4x4:3 capability

HTH

Rasika

**** Pls rate all useful responses ****

New Member

Re: Cisco AP 3700 PoE

Dear Rasika,

Thanks... I think this 18W is only needed with Extension modules - see screenshot. Also on the Datasheet it is mentioned 15W...

What do you think?

New Member

Re: Cisco AP 3700 PoE

Hall of Fame Super Gold

Cisco AP 3700 PoE

This is incorrect. 

With the optional WSSI module, the 3700 will require a total of 25.0w PoE. 

I have no idea where you got this document but look at the data sheet for the 3700 and you'll see a MINIMUM requirement of 20.0w. 

New Member

Cisco AP 3700 PoE

Dear Leo,

I'm at the datasheet for Cisco AP 3700:

http://www.cisco.com/c/en/us/products/collateral/wireless/3700-series-access-point/data_sheet_c78-729421.html

There is "Power Draw" = 15W

Can you please point me to the datasheet where 20W is stated?


Regards

Manuel

Hall of Fame Super Gold

Re: Cisco AP 3700 PoE

Can you please point me to the datasheet where 20W is stated?

Look below "Power Draw".  Look at "Power Options".

Hall of Fame Super Gold

Re: Cisco AP 3700 PoE

Note: If 802.3af PoE is the source of power, the access point will dynamically shift from 4x4 to 3x3 and come up under PoE.

The line above is taken directly from the Data Sheet of the 3700.  This is meant to be confusing because the Data Sheet was written by the marketing people. 

If you read between the lines it means that if you use only PoE (15.4w) then MIMO will down-shift from 4X4 to 3X3.  What is not written along this line is that if you want 4x4 MIMO then you need to use 802.3at PoE+.

New Member

Re: Cisco AP 3700 PoE

OK... so let's say;

- Cisco AP 3700 (without Expansion Modules) require 20W (incl. Power Link Loss) at Switchport (PSE) correct?

Regards

Manuel

Hall of Fame Super Gold

Re: Cisco AP 3700 PoE

- Cisco AP 3700 (without Expansion Modules) require 20W (incl. Power Link Loss) at Switchport (PSE) correct?

This is correct.  A "clean" AP 3700, without any optional module installed, will require 20.0w PoE to operate 4X4:3. 

New Member

Re: Cisco AP 3700 PoE

and with 3X3:3 it is 15.4 at the Switchport correct?

Hall of Fame Super Gold

Re: Cisco AP 3700 PoE

and with 3X3:3 it is 15.4 at the Switchport correct?

It's not 3X3:3 when 15.4w.  It's 3X3:2 when operating at 15.4w. 

New Member

Re: Cisco AP 3700 PoE

Thanks Leo!

- The 20W for AP 3700 (without expansion modules) is inclusive PoE-Link-Loss correct?

so the AP itself requires approx 18W...

- What is the main difference between 4X4:3 / 3X3:3 / 3X3:2?

Regards

Manuel

Hall of Fame Super Gold

Cisco AP 3700 PoE

- What is the main difference between 4X4:3 / 3X3:3 / 3X3:2?

MIMO is Multiple In, Multiple Out.  So this means that 4X4 is how many IN (4) and how many OUT transmission (4).  the ":3" is the amount of spatial stream.

- The 20W for AP 3700 (without expansion modules) is inclusive PoE-Link-Loss correct?

so the AP itself requires approx 18W...

Seriously now, who's still looking for Link-Loss?  It's 20.0w.  I am not pedantic. 

New Member

Cisco AP 3700 PoE

Many thanks! sorry i'm usually not nitpicky... i was just wondering if i was looking from the correct perspective meaning PSE or PD site... the reason why i'm saying this, is that we bought new AP 3700 and the Power Budget on the current switches is not that huge anymore but we would like to keep the switches for a moment so additional 2-5W per Port could be a topic..

I wish you a nice day...

Greetings from switzerland

Manuel

Hall of Fame Super Gold

Cisco AP 3700 PoE

Don't forget to rate our useful posts, Manuel. 

New Member

Cisco AP 3700 PoE

I will do for sure... so for my new 3700 AP i will budget 20W on the Cisco 3650 Switchport...correct me if i'm wrong and sorry for beeing nitpicky!

Hall of Fame Super Gold

Cisco AP 3700 PoE

I will do for sure... so for my new 3700 AP i will budget 20W on the Cisco 3650 Switchport...correct me if i'm wrong and sorry for beeing nitpicky!

3650?  The NEW 3650 or the old 3560? 

3560/G will only support up to 15.4w.  3560E/X will support up to 20.0w maximum. 

3650 can support up to 30.0w PoE. 

However, you need to be careful with what you are planning to do.  You need to calculate the TOTAL PoE power each unit can do.  Some PoE switch can only provide 24-ports at 15.4w PoE.  Some switches, depending on the size of your power supply, can support up to 37 PoE ports at 20.0w.

New Member

Cisco AP 3700 PoE

Leo,

It's the new Cisco 3650 24x Port PoE Switch (640WAC - 390W PoE-Budget). For the PoE-Budget on the Switch i was calculating the following;

- 8x 3700 AP's (without Modules) = 20W = 160W

- 16x Cisco 9971-Phones (without Camera) = 12.3W = 196.8W

Total = 356.8W

We should be fine with this...or what do you think?

P.S: As far as i know, the Cisco 3650 can deliver 30W at each Port (assuming 2x 640WAC or 1x 1025WAC Power Supply) correct?

New Member

Cisco AP 3700 PoE

"3560/G will only support up to 15.4w.  3560E/X will support up to 20.0w maximum."

--> Cisco 3560X can also support 30W per Port or do i see something wrong?

Thanks again...

Hall of Fame Super Gold

Re: Cisco AP 3700 PoE

It's the new Cisco 3650 24x Port PoE Switch (640WAC - 390W PoE-Budget).

This means you can get a maximum of 19 ports at full 20.0w PoE.  Also consider how important this switch is because you could add a second power supply to the switch in case the primary fails.

We should be fine with this...or what do you think?

This will work.

Cisco 3560X can also support 30W per Port or do i see something wrong?

Yes, the "X" can support 30.0w. 

New Member

Re: Cisco AP 3700 PoE

Dear Leo, Thanks a lot for your awesome and fast answers... i have just one question i would like to ask you.

I'm interested - why are you calculating with 20W, is this because of the 3700 Access Point? Usually i see numbers like 15.4W (802.3af) or 30W (802.3at). As far as i know the Cisco 3650 Switch could to both on any Port.

Just wondering...

Thanks

Manuel

Hall of Fame Super Silver

Re: Cisco AP 3700 PoE

You try to calculate power budget based on the max required for a given access point. The 3702 with expansion module requires PoE+. A minimum of 15.4 is required to power up the AP but at a cost of dynamically shifting from 4x4 to 3x3 or 2x2.

It explains it in the data sheet below

Powering options
Aironet 3700 without an add-on module
? 802.3at PoE+
? Enhanced PoE
? Cisco AP3700 power injectors (AIR-PWRINJ4=)
? Cisco AP3700 local power supply (AIR-PWR-B=)
Note: If 802.3af PoE is the source of power, the access point will dynamically shift from 4x4 to 3x3 and come up under PoE.
Aironet 3700 with an add-on module
? 802.3at PoE+
? Enhanced PoE
? Cisco AP3700 power injectors (AIR-PWRINJ4=)
? Cisco AP3700 local power supply (AIR-PWR-B=)
Note: If 802.3af PoE is the source of power, the access point with module will dynamically shift from 4x4 to 2x2 and come up under PoE.




Sent from Cisco Technical Support iPhone App

-Scott
*** Please rate helpful posts ***
Cisco Employee

Bear in mind AIR-PWRINJ6=

Bear in mind AIR-PWRINJ6= will be the official power injector because AIR-PWRINJ4= will be EoS in Nov-20-2016.

Regards

Hall of Fame Super Gold

Cisco AP 3700 PoE

why are you calculating with 20W, is this because of the 3700 Access Point?

Correct.

Usually i see numbers like 15.4W (802.3af) or 30W (802.3at). As far as i know the Cisco 3650 Switch could to both on any Port.

A lot of the new switches nowadays, 3560X, 3750X, 2960S/X, 3650 and 3850 can do 15.4w, 20.0w and 30.0w. 

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