Patent ID: 8064340

Claim:
A quality-degraded portion estimating apparatus, comprising: an information collection device for collecting quality information and flow rates of flows circulated in a network as well as structural information of the network; a quality-degraded flow/quality-non-degraded flow determining device for finding links through which the flows pass from the flow quality information and the network structural information collected by the information collection device, and determining quality-degraded flows and quality-non-degraded flows based on a degrading threshold value and a non-degrading threshold value determined in advance; and a quality-degraded portion estimating device for, from a set of the links through which the quality-degraded flows pass, outputting as quality-degraded portions, a subset having a minimum element number and including a link through which an arbitrary flow among the quality-degraded flows passes, which is among subsets of the link set from which the link having number of passing quality-non-degraded flows equal to or larger than a non-degraded flow number threshold value that is determined based on the degrading threshold value and the flow rate is eliminated, wherein the quality-degraded flow/quality-non-degraded flow determining device changes, for a set of the quality-degraded flows that pass a link through which a given quality-non-degraded flow passes, the non-degraded flow number threshold value depending on number of elements of a set configured with minimum number of links among link sets in which a set of flows configured with quality-degraded flows that pass any of links of a link set through which any of the flows in the quality-degraded flow set passes includes the set of the quality-degraded flows, and wherein, when the non-degraded flow number threshold value becomes high such that a link having more than a prescribed number of the non-degraded flow is eliminated, the quality-degraded portion estimating device finds the link as a non-degraded link with which a number of a link set through which the quality-degraded flows pass increases.