the C4K can handle 3 Power supplies.
the chassis : WS-C4006-S3 has by defualt 2 power supplies.
do they work in :
-active/standby mode : so in this case, why we can need the third power supply?
-or both units r working together at the same time: so in this case, can one power supply be enough if we have few cards? if yes from wich threshold?