Can a PoE port on the 2960x switch be configured as a PoE+ port?

[RabbitSF]

We got six 2960x switches (48-port) deployed this summer in our school and I have all our 3702i APs connected to them and they are powered by the PoE from the switches. But that will downgrade the APs to 3x3:3 mode. 

Our IT consultant told me that "your 2960's do support 24ports total of PoE+.  However, it may be required that we define the ports and isolate ports not using PoE and disable the features on those ports.". 

So I wondered if that is true that we can change some ports on the switches from PoE to PoE+.  If yes, is it going to be stable? What risk will I have?

Thanks much!

[Leo Laohoo]

Our IT consultant told me that "your 2960's do support 24ports total of PoE+.  However, it may be required that we define the ports and isolate ports not using PoE and disable the features on those ports.".

This statement is counter-productive.  Leave the PoE negotiations at default and the ports will negotiate to PoE+ (20.0w).  However, please take note the total amount of PoE power (375w per 24-port switch) available.  

[RabbitSF]

My 2960x is 48-port switch. What the IT consultant meant is to have 24 ports or less isolated and give them 20w while at the same time disable the PoE feature for all remaining ports. 

So what you are saying is if I plug 4 APs to one 2960x (48 ports) switch, those APs will get the 20w automatically if the ports are configured as negotiations at default. Is that right?

Sorry if I misunderstood you. Thanks much!

[Leo Laohoo]

So what you are saying is if I plug 4 APs to one 2960x (48 ports) switch, those APs will get the 20w automatically if the ports are configured as negotiations at default. Is that right?

Correct.

[RabbitSF]

Do you have any documentation or site from Cisco that can confirm what you said is correct? 

Not that I don't trust you but I need to show it to our IT consultant. Thanks much for answering my questions!

[Leo Laohoo]

Power Draw

* This is the power required at the power sourcing equipment (PSE)

Power Input Type

Environment Condition/Heaters

Wi-Fi Radio Mode

PoE Out

Power Budget (Watts)

PoE 802.3af

> -20°C No heaters active

3x3:3 on 2.4/5 GHz

N/A

15.4

PoE+802.3at

> -20°C No heaters active

4x4:3 on 2.4/5 GHz

N/A

21

PoE+802.3at4

-50°C to -20°C Still air 1 heater active

4x4:3 on 2.4/5 GHz

N/A

30

[RabbitSF]

I am afraid you probably did not get what I was trying to ask.

I was asking if you have any document or site that tells from a 2960x PoE switch the APs will get 20w automatically if the ports are configured as negotiations at default.

[Leo Laohoo]

I was asking if you have any document or site that tells from a 2960x PoE switch the APs will get 20w automatically if the ports are configured as negotiations at default.

The default behaviour of the port can be found in the command "sh power inline". 

PoE negotiation is based upon CDP.  When an powered device (PD) is first attached to the switch port, the switch does NOT know how much power it requires and the switch will push standard power, 15.4w, down the port.  The PD then powers up and will then ask for additional powered, again based on CDP, and switch will push down more power required.  

This is how PoE, PoE+, uPoE works.  There is no "documentation only for PoE+/uPoE" because they all follow the same guidelines (in power negotiation).  Nothing is different about the three standard.  

The only time administrators use static power values is when the PD don't talk CDP.  

[RabbitSF]

Does the following look good? They are not drawing 20w but 16.8w. Does that mean they are running 4x4? Thanks so much for all your answers. We are getting close.

[Leo Laohoo · Accepted solution]

Does the following look good? They are not drawing 20w but 16.8w. Does that mean they are running 4x4? 

Yes.  AP is running 4x4:3.  

Look at the right-most column (under the heading "Max").  This means the switch can supply up to 30w to some ports on a first-come-first-serve-until-exhausted. 

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[RabbitSF]

Excellent. Thank you so much!