A method of determining the location of a disconnection on a digital subscriber line, in particular a VDSL line, where the line has a number of nodes or connection points along it. A statistical model is generated from a population of lines that maps the loop (line) lengths of each of those lines obtained by line test measurements (such as single ended line test tracesSELT traces) against the corresponding loop lengths obtained from inventory data. The model is then used to determine a predicted loop length by mapping a measured loop length (taken from line test measurements) onto an inventory loop length using the model. Knowledge of the node positions on the line is then used to give a probability a line disconnect occurring at a given node by mapping the predicted loop length onto the node positions.

Detecting a short disconnection in a digital subscriber line, for example where the disconnection is near the DSLAM. A SELT UER trace is obtained from the digital subscriber line. The trace is analysed to determine its smoothness, as relatively smooth traces result from shorter lines. The smoothness measure can be calculated by applying some function to the differences of the amplitude between successive frequency tones. Two examples of functions that have been found to work well are a sum and a standard deviation. The result of the function can be compared to a threshold to determine if a short disconnection has occurred. Such a situation can occur when a cable has been disconnected from a patch panel for example.

The present disclosure provides a system (110) and a method (400) for network tracing using a command line interface (CLI) (112). The system (110) is integrated with the CLI (112) to provide location information of the concerned subscriber to an external client, trace requests from the subscriber in an efficient manner. The CLI (112) enables network tracing and subscriber tracing, thereby increasing efficiency to determine a root cause of a request failure from the subscriber.