Patent ID: 7587511

Claim:
A bandwidth monitoring device suitable for use in a network on which specific type of packets are transferred in preference to packets other than the specific type of packets, comprising: a receiving unit for receiving a packet from a specific source: a detecting unit for detecting flow of the received packet by judging whether the received packet coincides with a flow condition pre-defined with at least one of in-header information items other than priority information; a determining unit for determining whether the received packet is of the specific type or not based on the result of the detected flow; a monitoring unit for monitoring whether the received packet violates a contract bandwidth for the specific type of packets under a contract with the specific source; and a transmitting unit for transmitting the received packet after converting it to a packet having a specific value in its header that is indicative of the specific type of packets when the received packet does not violate the contract bandwidth for the specific type of packets and the received packet does not correspond to the specific type of packets.