Abstract: Protocol Parser—Code Generator. A protocol parser—code generator provides use of a protocol definition language for allowing protocol information to be decoupled from operating systems and computer languages. For producing protocol knowledge of the structure of a protocol data unit for use in the analysis of network frame traffic, the invention works by allowing the use of a protocol definition language to define the data structure of fields in a protocol data unit in keywords. A parser associates each of the keywords describing the data structure of the fields with a corresponding table of a set of tables. Each table is linked together and has a data structure fields. A code generator then generates field code for each of the tables for use in providing protocol knowledge of the data structure of each of the fields of the protocol data unit.