The Cisco RPS 675 Redundant Power System (model PWR675-AC-RPS-N1=)provides N+1 redundancy. It provides seamless failover to internal power supplyfailures for one of (up to) six switches. The RPS 675 automatically senses whena connected device has experienced an internal power supply failure andseamlessly and immediately begins to supply power to the device, providingcontinuous uptime with no need to reboot. When the RPS is supplying power to adevice, it cannot provide power to another device until the failed device's powersupply unit is replaced, or the device is replaced, and the RPS is returned to activemode. - Cisco Power Supplies