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AIR-PWRINJ4 power compatability

WS-3750G-48TS-S switches in stack mode with a max of 15.4 watts POE on each port

AIR-CAP3602E-E-K9 Wireless Access Points running 2.4 and 5GHz. Power currently being provided by switch using POE.

Cisco AIR-ANT2524DW-R (WHITE Antennas)


We wish to purchase the 802.11ac modules (AIR-RM3000AC-E-K9=) for the 3602e APs  and continue to run 2.4 and 5GHz. According to the documentation (source) we need to provide 18+ watts of POE power for both 2.4 and 5GHz bands.


So we are looking at getting Cisco POE Injectors. (AIR-PWRINJ4)


However, from what we've understood from the following documentation ( is that a midspan POE injector (in this case ‘AIR-PWRINJ4’) cannot transmit 802.3af POE over a 1000base T connection?


Quote from the above article: Quote from the above link “Mid-span PSE—Can be used to deliver PoE if an existing non-PoE-capable Ethernet switch is used. If a mid-span PSE is used, it can only implement power delivery over the spare pairs of the copper cabling and cannot be used to deliver PoE over 1000BASE-T connections.”


Can someone confirm that we are not therefore able to use 1Gb ports on the 3750G's for the connectivity?

Hall of Fame Super Gold

WS-3750G-48TS-S won't do PoE.

WS-3750G-48TS-S won't do PoE.  


PWRINJ4 will work.  But you need to aware of the following things: 

1.  PWRINJ4 doesn't dictate what speed your AP will negotiate to.  The negotiated speed of your AP boils down to the configuration of your switchports and the quality of your cable.  If your cable has a faulty pin, then it won't negotiate to 1 Gbps. 


2.  I wouldn't be bothered investing in the AC module.  This is particularly true when you have multiple AC module on a single switch.  Why?  802.11ac, wave 1 is capable of pushing up to 1.3 Gbps.  What is your uplink speed?   It just ain't worth the hassle and the trouble.  You may want to look at 3700 and the soon-to-be-released 3800.   AP3700 supports 802.11ac, wave 1 natively (no module required but still requires PoE+) and 3800 will support both 802.11ac wave 1 and wave 2 natively (no module required but still requires PoE+).


Hello, rufusleonard. How many

Hello, rufusleonard. 

How many 3602 APs are you considering having AC modules? Going with the new 3700 with built in AC would be a better investment instead. 

Let me know if you have other Cisco concerns or e-mail ( me directly. Kind regards.