Enhanced PoE port power available from switch?

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Aug 24th, 2010
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Can a WS-C3560E-24PD-S switch with a C3K-PWR-750WAC power supply, provide enough power to supply enhanced PoE of 20 watts (Power draw of access point per data sheet of model 1252 Wireless access Point with 2 radios) for all 24 ports simultaneously?


If not, how does it work?  4 ports get nothing?  All ports get less power?   Circuit breaker pops?  


I'd appreciate it if any answer gets supported by showing calcs and/or pointing to spec sheets - as I need this information for our engineering design basis.



Thanks in advance...

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paolo bevilacqua Tue, 08/24/2010 - 13:47
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20 x 24 = 480W.

PS is 750W.


Data sheet says:

• Enhanced PoE supporting up to 20W of PoE per port


•  Industry first portfolio to scale beyond 15.4W per port delivering  maximum solution simplicity for 802.11n access point deployments


It will work no problems

rmalleck0508 Wed, 08/25/2010 - 05:14
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Thanks for the replies!


From the switch spec sheet in table 5 "Power Specifications" under the conditions: "100% Throughput (With Maximum Possible PoE Loads)", the measured power consumption for the switch itself is:  502 watts


Under this condition:   Switch itself + 24 ports of EPoE power sourcing

                                502 watts  + (24 * 20 watts)

                                502 watts + 480 watts = 982 watts


                                 982 watts > 750 watt rating of the power supply


                         

So what happens under these conditions?



Even for this load condition for normal PoE (15.5 watts per port) from the spec sheet Table 5 "Power Specifications" again:

Measured Power Consumption is:   "502 Switch and 372 PoE Power"

372 = 15.5 * 24


So even under this condition, power consumption is (502+372) = 874 watts, which appears to be above the 750 watts available.

Leo Laohoo Tue, 08/24/2010 - 15:11
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WS-C3560E-24PD-S switch with a C3K-PWR-750WAC

That should be no problem.  Upgrade your IOS to 12.2(46) to enable enhanced PoE.

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