A method for profiling network traffic of a network. The method includes extracting cells from bi-directional payloads generated by a network application, wherein each cell comprises at least one direction reversal in a corresponding bi-directional flow, generating a cell group comprising a portion of the cells that are similar, analyzing the cell group to generate a signature of the network application, and classifying, based on the signature of the network application, a new bi-directional flow as being generated by the network application.