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IAP-275 problem with powering from mediaconverter


I have strange problem with powering IAP-275 from mediaconverter (Microsens MS657099PX, unmanaged, compliant with IEEE802.3af/at PoE+ standard) - only a half of them turned on. I tried to reseting mediaconverter, or to replug AP, but nothings work - still mediaconverter doesn't supply power. 

I also tried to connect to the same mediaconverters other IAP-275 which I have as a back-up, and at every time it turned up without any problems. 

It looks like it is a device incompatibility, but every mediaconverter, and IAP are exacaly the same model from the same delivery. 



MVP Expert

Re: IAP-275 problem with powering from mediaconverter

Sorry for the delay. Note that your media converter is not 802.3at rated, but is 'POE+' rated which is just a higher wattage version of 802.3af (POE+ is NOT a standard, it was a generic description generated by Cisco back in the day). 

802.3at has a higher nominal voltage requirement (54V) over 802.3af (48V). This is done to help overcome longer cable runs to ensure the voltage drop of a long cable to ensure proper voltage at the other end. As such, APs and devices that require 802.3at like the 275 won't always work on POE+ 'rated' converter, and additionally, 802.3at compliancy is required. Chances are the ones that ARE working are shorter runs, have better quality cables, or are terminated better than the ones that aren't. But you will need to use 802.3at rated POE injectors/media converters to get full support and then everything should work fine.

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