Abstract: A method is disclosed of detecting a failed link in a network over which nodes are interconnected via links. The nodes include an observer node and a managed node. This method, implemented for the observer node, includes: determining, for each of prefixes in receive route-update messages, a single normal-state path; determining, for each of the links (i.e.

Abstract: A method is disclosed of detecting a failed link in a network over which nodes are interconnected via links. The nodes include an observer node and a managed node. This method, implemented for the observer node, includes: determining, for each of prefixes in receive route-update messages, a single normal-state path; determining, for each of the links (i.e.

Abstract: A method and a management apparatus for classifying congestion paths based on packet delay in a plurality of paths between measurement nodes. The method and the apparatus specify the short-time congestions based on packet delay in Internet Protocol network.

Abstract: The present invention detects a failure location of network in the Internet. A pair of networks consists of an access network and an Internet service provider network, and a route consists of a source pair of networks and a destination pair of networks. The quality information values are inputted to elements in a matrix that all pairs of networks are put in same order as rows (or columns) of source pairs of networks and columns (or rows) of destination pairs of networks. If inferior quality values in the matrix line up in the row (or column), a failure is determined in a destination (or a source) pair of networks in column side (or row side) corresponding to a row (or a column). If inferior quality values line up in a slanting direction, a failure is determined in a route between the Internet service provider networks indicated to the slanting direction.

Abstract: A method for classifying congestion paths based on packet delay in a plurality of paths between measurement nodes, has the following steps. First, it receives a measurement data unit including an origin node, a destination node, and a sent time and a received time in a received packet from the measurement node. Then, it arranges the measurement data units of the same origin node in order of sent time, and extracts a pair of measurement data units of which an interval time between the sent times of adjacent measurement data units is less than the threshold time. Then, it arranges the measurement data units of the same destination node in order of the received time, and extracts a pair of measurement data units of which an interval time between the received times of adjacent measurement data units is less than the threshold time.

Abstract: The present invention detects a failure location of network in the Internet. A pair of networks consists of an access network and an Internet service provider network, and a route consists of a source pair of networks and a destination pair of networks. The quality information values are inputted to elements in a matrix that all pairs of networks are put in same order as rows (or columns) of source pairs of networks and columns (or rows) of destination pairs of networks. If inferior quality values in the matrix line up in the row (or column), a failure is determined in a destination (or a source) pair of networks in column side (or row side) corresponding to a row (or a column). If inferior quality values line up in a slanting direction, a failure is determined in a route between the Internet service provider networks indicated to the slanting direction.