US Patent 9479409 Passive reachability measurement for inline service chaining

A method is implemented by a computing device in communication with a network having a plurality of switches. The method performs path correctness testing where the path defines a service chain associated with a flow of data. The method configures the plurality of switches using a flow control protocol. The method includes the steps of selecting a switch from the path to configure path correctness testing, sending a configuration request to the selected switch to instate at least one rule for testing path correctness, receiving copies of flow packets from at least one switch in the path, and comparing the copies of flow packets with a service chain configuration of the flow to confirm path correctness.