 The assumption is made that the combined capacities of the two inlet branches are less than the capacity of the outlet branch, μ1+ μ2 ≤ μ.There are four possible states for the system to have based on the level of flow occurring in each inlet.Each inlet can be either in free flow or congestion, and thus the system can have both inlets in free flow, one or the other in congestion, or both in congestion.