Patent ID: 8681794

Claim:
A switch for performing packet inspection, comprising: a flow tracker that reviews packets that enter the switch at an ingress pipeline, said flow tracker creating an entry in a flow tracker session table on identification of a new flow of packets to be tracked, said flow tracker reviewing a packet associated with a previously identified flow and generating flow information to be forwarded with said reviewed packet to a memory management unit in said switch, said flow information including a flow index that identifies a particular flow of packets to which said reviewed packet is associated; and a signature matching engine in an auxiliary pipeline of the switch that receives said reviewed packet and said flow information from said memory management unit in the switch, said signature matching engine examining said reviewed packet using context state information that is retrieved from a state table in memory of said signature matching engine using said flow index, wherein said retrieved context state information identifies a state of examination of an expression matching state machine in examining a prior packet in a flow identified by said flow index, wherein results from said expression matching state machine are included by said signature matching engine in a response packet that is sent by said signature matching engine to said ingress pipeline of the switch.