Abstract: A communication system, in one embodiment, has set top boxes that the have the ability to monitor the subnet to which they are coupled. A multicast router couples one or more groups, such as groups of video programs, to the set top boxes as requested by the set top boxes. If one set top box leaves a first group, for example, and thus sends a leave message to the router, the other set top box or boxes know to send a join message if they are subscribed to that first group. Thus, the router knows immediately to couple that first group on that subnet.

Abstract: A communication system, in one embodiment, has set top boxes that the have the ability to monitor the subnet to which they are coupled. A multicast router couples one or more groups, such as groups of video programs, to the set top boxes as requested by the set top boxes. If one set top box leaves a first group, for example, and thus sends a leave message to the router, the other set top box or boxes know to send a join message if they are subscribed to that first group. Thus, the router knows immediately to couple that first group on that subnet.

Abstract: A method and system for selectively defining hardware parameters in an executable operating system program provides the advantage of enabling or disabling hardware features during testing without having to modify and recompile the operating system source program. In an implementation of a preferred embodiment, a hardware control variable is stored in a configuration file in memory. The configuration file is accessible to the user to define or modify the hardware control variable as desired. The hardware control variable contains a number of hardware control bits, each corresponding to a hardware parameter in the executable operating system program. During execution, the executable operating system program defines the hardware parameters based on the values of the corresponding hardware control bits. The executable operating system program enables or disables the hardware features based on how the hardware parameters are defined.