This document provides input for the selection of a default Bandwidth Constraints Model for Diff-Serv-aware MPLS Traffic Engineering (DS- TE). It discusses a number of considerations on Bandwidth Constraints Models and how the Maximum Allocation Model and the Russian Dolls Model address these considerations. While this document may not exhaustively cover all possible considerations for selection of a Bandwidth Constraints model, we feel it covers the most important considerations for practical DS-TE deployment. We conclude that the Russian Dolls Bandwidth Constraint Model is a good default Bandwidth Constraint Model for DS-TE.