RELAY DEVICE AND RELAY METHOD

PROBLEM TO BE SOLVED: To monitor network traffic from a remote environment on a real-time basis.SOLUTION: An MPLS-enabled layer 2 switch 18a has a function to store output port information, mirrors frames that pass through a prescribed port 31 and sends the mirrored frames that are mirrored to an encapsulating part 34. The encapsulating part 34 encapsulates the flames adding a label corresponding to information including a predetermined transfer destination address and sends the encapsulated frames to a switching part 27. The switching part 27 outputs the encapsulated frames to an output port 29 corresponding to the output port information. The encapsulated frames output from the output port 29 are transferred to a measuring device in an operation center via a tunnel provided in advance in a network which includes a plurality of layer 2 switches.