Going to Use Cisco’s 3700 11ac Access Points? Know Your PoE

Like a lot of Cisco WLAN customers, I’m about to steer my wireless ship into the 802.11ac waters for the first time, using the flagship 3700 AP.

Having been around the block a few times with new Cisco WLAN products, I’ve been reading everything I can in various places to make sure my group has a handle on controller code and POE concerns before we deploy in prod. It’s worth talking about that PoE thing a bit, because reality isn’t so obvious.

From the 3700’s data sheet:

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You really have to pay attention to get the nuance here: the power draw is 15W… or maybe it’s not. And… if you don’t power your 3700 properly, with 802.3at PoE+ and an actual 20 Watts (without add-on modules), then you’ve turned your pricey 4×4 AP into a 3×3 AP.

Huh? But the data sheet says 15W! Where does this 20W thing come from? Perhaps the best dialogue on the topic is here, on the Cisco community forums. I’m not sure why the data sheet isn’t more clear about this rather important distinction, but there’s probably an element of not wanting to turn-off potential 3700 customers that don’t have beefy enough switches to get 4×4. And pay attention to the part about using optional modules, if that’s your pleasure- gets you into the 25W per AP range.

Bottom line? Make sure your 3700s each have 20 Watts available, or get used to seeing this:

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2 thoughts on “Going to Use Cisco’s 3700 11ac Access Points? Know Your PoE

  1. buckeys4life

    It could be worse. Cisco could in be Aruba’s shoes. The 225 drops to 1×3:1 in 2.4 GHz on .3af. I guess 11ac just requires more power.

    I actually think the data sheet calls things out pretty clearly. On 802.3af the 3700 shifts from 4×4:3 to 3×3:3.

    Reply
    1. wirednot Post author

      Thanks for the reply, Buckeys4life. If…if all you read is the bullets about shifting to 3×3, I’d agree with you but still say information is lacking. My point is that data sheet creates the feel that 15W is watt you need to power your new 4×4:3 access point- which is not true. Also, the information needed- 20W for 4×4 and even more if you are running modules- to build your PoE budget, is lacking. If the forum folks can summarize it so nicely, why can’t it be reflected on the data sheet accurately? My beef is with needing to hack around to find full and accurate information on this top-tier AP.

      -Lee

      Reply

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