Generating packet processing graphs

A system for generating a graph data structure for a packet processing system, the system comprising:

• a processor configured to generate a graph data structure from the plurality of packet processing rules, the graph data structure comprising a plurality of graph data objects representing classifier nodes of a packet processing graph, the classifier nodes including a root node and a plurality of leaf nodes, the root node being connected to each of the plurality of leaf nodes through respective corresponding packet processing paths through the graph,
• wherein each of said graph data objects includes node match data indicative of at least one match to be applied by the respective classifier node, and
• wherein the processor is configured to generate the graph data structure by identifying:
• one or more n-type match graph data objects which include node match data indicative of an n-type match corresponding to content from n header field types, where n is an integer value of 1 or more;
• and
• one or more (n+m)-type match graph data objects which include node match data indicative of an (n+m)-type match corresponding to a combination of content from a (n+m) different header field types, where m is an integer value of 1 or more.