1. A method for estimating a DSL system test loop configuration, the method comprising: obtaining a test loop parameter vector from the test loop of the DSL system, wherein the test loop parameter vector comprises one or more loop-dependent parameter values; selecting a reference parameter vector corresponding to a reference loop configuration; computing the difference between the test loop parameter vector and the reference parameter vector; and estimating the test loop configuration based on the computed difference between the test loop parameter vector and the reference parameter vector.