This paper addresses the modeling of specific Smart Grid (SG) communication requirements from a data networking research perspective, as a general approach to the study of different access technologies suitable for the last mile (LM). SGLM networks serve customers' Energy Services Interfaces. From functional descriptions of SG, a traffic model is developed. It is then applied to the study of an access architecture based on leased lines from local broadband access providers. This permits consideration of the potential starvation of domestic traffic, which is avoided by applying well-known traffic management techniques. From previous results obtained for a purpose-built WiMAX SGLM network, the intuition that a leased broadband access yields lower latencies is verified. In general, the proposed traffic model simplifies the design of benchmarks for the comparison of candidate access technologies.