Hot-swappable router interface card with stable power on/off procedure

A network router includes hot-swappable physical interface cards that allow the router to communicate using a variety of network technologies. Power to the interface cards is sequentially ramped to avoid disruptive power surges. The router includes multiple power supplies, a power monitor circuit, power on/off control circuitry, and a controller. The controller detects the presence/absence of the physical interface cards and controls the power monitor circuit and power on/off control circuit to sequentially ramp or sequentially remove power to the physical interface cards.