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Recently, I came across a new term for me: power budget

1) Each PoE device comes rated with a certain voltage/amperage. If you are limited by switch to a certain number of ports (say 24). How does power budget factor in. Each AP device or midspan device is capable of a max yield of 15.4 watts per class 0 or 3 device. My question is the power that is supplied through the switch is responsibility of the switch manufacturer. Why (as wireless administrator) do i care about power in the closet? Is it because other devices (other than the poe switch) is in the closet?

2) Do we need to know more electrical engineering calculations in the future because of problems such as posed by questions like these?

jamig77

I believe they are refering to the fact that a Cisco POE switch has a tolatol (one big amount) power budget. When this amount is reached. No other port can come up and use POE!! So even if you have ports left, but the max amount of power avalible from the switch is used, than no more POE on that switch!!
Why shjould you be concerned. As a wireless Eng. In the end, you need to get all the gear powered and if you didn't state what and how much power you needed, the $ will stop at you!! That is the power budget you need to run all your gear. And the ones in chage of the closet, need to add more for there own or other gear..

Hi,

here i.e. you could see a Cisco switch were you could install a second PSU to increase the amount of PoE ports that you could have in the chassis as the power from only one PSU could be not enough for your installation..

http://www.cisco.com/en/US/products/hw/switches/ps4324/prod_bulletin0900aecd802d5351.html

Cheers,
Ron