Cisco 3650 PoE+ and Power Supplies

[Reuben Farrelly]

I'm looking at deploying a few 3650 switches at some regional sites, where there is a requirement for PoE+ to power access points, but only on a small number of ports.

Table 7 at this URL:

http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-3650-series-switches/qa_c67-729531.html

states that I need 2x 640W power supplies in order to provide PoE+, but it appears that this is based on PoE+ being required for all ports all of the time (which isn't the case for me).  Nearly all the data sheets and documents I've come across assume the maximum PoE+ load also.

Is there any restriction on these switches which may stop me supplying 30W PoE+ to only a small number of ports (staying withing power budget) when running a single 640W power supply?

Or does the switch fall back to 15.4W PoE if only a single PSU is installed regardless of power budget?

[Leo Laohoo · Accepted solution]

Depends on your model and your PS.

All 3650/3850 can support 30.0w PoE.  So if you have, say a 48-port switch and you have a PS of 720w then you get, at most, 24 ports (720 / 30 = 24) that can support 30.0w on a first-come-first-serve-basis-until-full. 

[Reuben Farrelly]

Thanks - for the response and also for taking the time to reply Leo.

[Leo Laohoo]

Thanks for the time to rate our posts, Reuben.