On-line insertion of line replaceable units (such as circuit board cards) into a backplane of a processor shelf, a modem shelf, or a similar type of equipment utilizes at least one interface control processor card that is capable of functioning as a primary master controller to control the insertion of circuit board cards into the backplane. Circuit board cards that are newly inserted into the backplane do not automatically have access to full power, or to the buses, or to other cards in the backplane. A newly inserted circuit board card remains isolated until the primary master controller checks, configures, and authorizes the newly inserted circuit board card to operate. A secondary master controller is provided to function as the primary master controller if the primary master controller fails. An automated boot procedure is provided to enable a circuit board card to determine whether it is a master controller, and if so, whether it is a primary master controller or a secondary master controller.