A method of providing a data file that defines a modified SONET ring network including at least one sub-tending ring is disclosed. The method comprises identifying a set of low data rate sub-tending ring candidate traffic handling elements within a SONET ring network to be modified. For a first candidate element of the set of low speed sub-tending ring candidate traffic handling elements, the method includes evaluating selected characteristics of a first parent SONET UPSR ring with respect to adding the first candidate element sub-tending SONET ring. Based on a positive evaluation of each of the selected characteristics of the parent SONET ring, the method includes creating a data model that indicates addition of the first and subsequent candidate element sub-tending SONET ring to the parent SONET ring, and providing a data file based on the data model that defines a modified SONET ring network including the parent SONET ring(s) and the sub-tending SONET rings.