Control of operating states of channel unit installed in performance

Abstract

A performance monitoring arrangement conducts auxiliary communications between a performance-monitoring capable line interface unit and one or more performance-monitoring capable channel units of a D4 channel bank without interrupting transmission of digital data to and from a customer premises. During each of an initialization mode and a performance-monitoring mode, the data communication format of a channel bank bus is modified to allow insertion of an auxiliary line interface unit-sourced command bit between selected bits of the data. During the performance-monitoring mode, the communication format of the channel bank link is further modified to provide for insertion of a response bit from a channel unit and the transmission of data at an increased data rate. In the absence of an indication that there is an anomaly that would impair the operation of the channel bank, the channel unit transitions to a performance-monitoring mode of operation. If either of the channel unit and line interface unit is not capable of conducting performance-monitoring communications with one another, and in the absence of an indication that there is an anomaly that would impair the operation of the channel bank, the channel unit transitions from the initialization state to a normal mode of operation.