Cisco AP 3700 PoE

[mlinder01]

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

[mlinder01]

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

[Leo Laohoo]

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. 

[mlinder01]

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

[Leo Laohoo]

- 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. 

[mlinder01]

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

[Leo Laohoo]

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

[mlinder01]

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!

[Leo Laohoo]

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.

[mlinder01]

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?

[mlinder01]

"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...

[Leo Laohoo]

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. 

[mlinder01]

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

[Scott Fella]

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

[emontene]

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

Regards

[Leo Laohoo]

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.