Maintenance of asymmetrical digital subscriber lines (ADSLs)

Provides an approach and functions for maintaining ADSL links, to ensure the support of video dial tone (VDT) and other services; to end-users over existing copper plane. The maintenance approach and functions are presented in terms of end-to-end near term DS1 and later term SONET and ATM service delivery architectures. The objective is to provide a cost effective means of detecting service trouble and locating and diagnosing its cause for rapid repair and return to service. This is achieved through use of in-service surveillance from advanced rate and format signals (with operations channels and near-end and far-end overhead maintenance indicators), and from embedded network and loop maintenance capabilities