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!
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.
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This should help:
• 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.
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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.
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?
As Leo said, it is 20W at the switch end (PSE). AP itself required ~18W to have full 4x4:3 capability
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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?
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.
I'm at the datasheet for Cisco AP 3700:
There is "Power Draw" = 15W
Can you please point me to the datasheet where 20W is stated?
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+.
- 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.