Nippon Telegraph and Telephone Corporation

Michihiro Aoki

Nobuaki Matsuura

Koji Sugisono

Shigeo Urushidani

Hideaki Iwata

Takashi Kurimoto

Takashi Miyamura

Keisuke Kabashima

Hisashi Kojima

Ichiro Inoue

Tomonori Takeda

Masahiro Goshima

A path calculation order determining method executed by a calculating apparatus for calculating a shortest path between a node pair in a network, using information on calculated shortest paths between other node pairs, the method including: a step storing calculated shortest path group information on shortest path groups each including calculated shortest paths from a starting node to one or more terminating nodes except the starting node, and topology information of the network, in a memory medium; and a calculation step of calculating shortest paths, starting from its starting node other than the starting node on the calculated shortest paths and having the most nodes that are located downstream therefrom, and terminating at nodes other than its starting node, using the calculated shortest path group information or the topology information for a path not included in the calculated shortest path group.

Path calculation order deciding method, program and calculating apparatus

A calculating apparatus calculates a shortest path connecting two nodes of a network. A shortest-path group, which is a set of shortest paths having node Y as their starting points, can be calculated at once by having calculated a shortest path having node Y as its starting point for each of other nodes. When the shortest-path group having node Y as the starting point is calculated and further if a group of shortest paths having node X as their starting points is stored beforehand in a storing unit, then path portions, which belong to the group of shortest paths having node X as the starting points and further which are paths extending from node Y to the nodes located downstream from node Y, are utilized as part of a result of calculation of the shortest path group having node Y as the starting point.

Path calculating method, program and calculating apparatus

An optical network has: sections for establishing optical paths; a plurality of optical edge routers for connecting external IP networks to the optical network (); and a plurality of optical cross connects, for connecting the optical edge routers by the optical paths, having switching sections with respect to an optical pulse unit. In the optical network, each of the optical edge routers has both of: (1) an optical network control instance (INSp) for maintaining topology information in the optical network and switching/signaling the optical paths; and (2) an IP network instance (INSi) for maintaining a routing table in each of the external IP networks and activating routing protocols between the external IP networks and the IP network instance. By doing this, it is possible to realize a multi-layer cooperative function and provide highly safe optical networks, etc.

Optical network, optical edge router, program thereof, cut through method, and edge router

A data transfer apparatus and a data transfer system are provided that can reduce the cost of installing communication equipment compatible with each of several dissimilar communication protocols in one exchange office and can reduce the cost of constructing the network. The data transfer apparatus includes a data reception device () that receives packets that comply with dissimilar communication protocols from upstream data transfer apparatuses (and); a content data extraction device () that extracts content data included in the packets; a line selection information storage device () that stores the line selection information for selecting communication lines that comply with dissimilar communication protocols; a line selection device () that selects the communication line compatible with content data based on the line selection information; and a data transfer device () that transfers data to downstream data transfer apparatuses (and) that are connected to the communication line that has been selected by the line selection device.

Data transfer apparatus and data transfer system

Growing community of inventors

Tokyo, Japan

Michihiro Aoki