PACKET PARSER

A packet parser is described that parses a packet by identifying the locations of respective packet layers. A staged approach to parsing the packet is employed whereby a first stage tests the packet data units within a first window for the presence of a first packet layer, and a second stage, at least partly in parallel with the first stage, tests the packet data units within a second overlapping window for the presence of a second packet layer. In response to an embedded packet comprising a first packet forming the payload portion of a second packet, the parser produces a data structure comprising first data that identifies the location of the first packet, second data that identifies the location of the second packet, third data that identifies one or more layers of the first packet, and fourth data that identifies one or more layers of the second packet.