Abstract: The present invention provides a test access path (TAP) concentration function. The apparatus supports subscriber loop testing for special access configurations (e.g., fiber-to-the-curb (FTTC)), where network units are physically clustered together into two or more non-collocated clusters. The apparatus supports test access to twisted wire pair subscriber loops, the lengths of which vary over a wide range. In one embodiment, the apparatus is a TAP expander that connects the TAP of an integrated digital terminal of a local digital switch with a derived TAP corresponding to one of the ONU clusters. The present invention allows an integrated digital terminal with as few as one test access path to be configured in a network having two or more non-collocated network unit clusters (e.g., ONU clusters), thereby supporting loop testing for all of the subscriber loops served by the integrated digital terminal without unnecessarily limiting the number of those subscriber loops.

Abstract: A circuit for cutting off power to selected components in a network which requires that backup power be supplied to other components. A monitoring signal is generated and combined with the power coupled to the components. A signal detector in the selected components determines the absence of the monitoring signal which is indicative of a commercial power outage. The signal detector then activates a cutoff mechanism which cuts off a portion of the component from the backup power without obstructing the flow of power and of the monitoring signal to the output of the component so power may be used by other downstream components.