Virtual channel assignment in a network is achieved by constructing a Traffic Conflict Graph (TCG) dependent upon a network interconnect topology. The TCG has vertices corresponding to traffic entries in a network specification and edges that connect pairs of vertices. An edge weight, dependent upon interconnect topology and traffic flow characteristics, is assigned to each edge. The vertices are colored using minimum or soft coloring and the virtual channels are mapped to the traffic entries, according to the resulting colors, to provide a virtual channel assignment. The TCG may be constructed by generating a vertex in the TCG to represent each traffic entry, assigning a traffic flow characteristic of a traffic entry to a corresponding vertex and generating an edge between first and second vertices when a number of ‘qualified’ common edges, across all routes for corresponding traffic entries, is greater than zero.