2702 AP POE

[Phil Bradley]

I have both Cisco 2702i and 2702e access points in my enterprise and have a question regarding POE vs POE+. My current switch stack, 3750G, only supports POE. According to the 2700 datasheet, this will force the AP's into a 3x3 instead of a 3x4 configuration. From my training, this typically is number of transmit and receive antennas respectively. The number of streams on these are still 3 so these AP's are either a 3x3:3 or 3:4:3 config. Will the extra receive antenna not available have an effect on bandwidth? The transmitters are also in reduced power mode according to the WLC but I don't have an issue with coverage. I am just trying to determine if I need to purchase POE+ injectors for these. Thanks!

[Leo Laohoo]

The number of streams on these are still 3 so these AP's are either a 3x3:3 or 3:4:3 config. Will the extra receive antenna not available have an effect on bandwidth? The transmitters are also in reduced power mode according to the WLC but I don't have an issue with coverage.

High MCS rates will be disabled.  This translate to wireless clients who can support high MCS rates will negotiate to the mid-level MCS rates.  

I am just trying to determine if I need to purchase POE+ injectors for these.

Up to you or the requirement.  A lot of wireless clients nowadays may say it can support 802.11ac but they don't/won't have the grunt to push 802.11ac data rates because they don't have CPU & battery power.  

In my opinion, buying injectors is just a waste of money.  Why?  In my experience with deploying injectors, it is nearly impossible to remotely reboot an AP.  Next, injectors require an additional patch cable and sometimes it's cables like these can be an issue.  Finally, if you've got four to six (and more) injectors all connected to the same switch, things get messy (and confusing) very quickly.

Mid-span PoE switch is the same but just as expensive as an injector. 

Cisco's current lineup of APs require 30w.  If it was me, I'd bite-the-bullet and ask management to pony up to upgrade the switches to ones that can support up to 35w per port (and mGIG).

[Phil Bradley]

Thanks for the info Leo. How do I determine if the MCS rates are disabled on the AP? When I look at the controller all of the MCS rates are supported.

[Phil Bradley]

After research and some wireshark captures, I do not believe that my higher MCS rates are disabled. I believe on the 2702i at POE, it has only lowered my transmitter output and limited my distance going from 3x4:3 to 3:3:3. This is from Intel's site:

When antennas outnumber spatial streams, the antennas can add receiver diversity and increase range.

I still have three transmitters enabled but only three receivers are enabled.

So I would like to confirm this and while it appears that these AP's will work fine with POE, my range will be degraded but not my throughput.