Nippon Telegraph and Telephone Corporation

Disco Abrasive Systems, Ltd.

Masanori Uga

Seisho Yasukawa

Koji Sugisono

Kohei Shiomoto

Shinichi Tamura

A method of establishing a multicast transfer route is disclosed that can reduce the cost of entire route under a constraint on delay incurred between starting point and ending points. The method includes the steps of: computing the shortest route with respect to delay connecting the starting point and the plural ending points based on measurement result; computing delay from a node on the shortest route to each ending point and the greatest delay; removing, if the greatest delay satisfies a delay condition, the greatest-cost route from the shortest route in accordance with selection criteria effective for cost reduction; dividing the multicast transfer route into two route trees; and establishing separately computed route as a complementary route that complement the removed route for connecting the two route trees. A method of multicast label switching for realizing the above method is also disclosed. A multicast label switching route is established using hierarchical labels by establishing a common multicast label switching route using a first layer label and establishing plural partial multicast label switching routes for subgroup destinations using lower layer labels. A relay node recognizes the hierarchical labels thereby to label-switch using all hierarchical labels.

Method of setting multicast transfer route and method of multicast label switching for realizing the same

A multicast communication path calculation method is disclosed which includes the steps of: obtaining minimum delay paths from a source node to each destination node; selecting, as candidate nodes of a rendezvous point node, nodes on one of the obtained minimum delay paths; for each candidate node, calculating minimum delay paths from the candidate node to each destination node, and obtaining a difference between the maximum value and the minimum value among delays of the calculated minimum delay paths; selecting, as the rendezvous point node, a candidate node by which the difference is smallest; and outputting a minimum delay path from the source node to the rendezvous point node and minimum delay paths from the rendezvous point node to each destination node.

Multicast communication path calculation method and multicast communication path calculation apparatus

Multicast transfer route setting method, and multicast label switching method for implementing former method

A packet classification search device and method are implemented which are capable of searching rules of packet classification having very long search bit width at high speed while using a CAM which has a limited bit width. The fields of rules of packet classification are grouped into groups, and the grouped fields of each rule are stored along with search related information (except for the initial group) and number of searches information in a CAM. The next number of searches information (if further groups exist which must be searched), comparison related information, and actions related to packets (if further groups exist which must be searched, directing searching again, while if no further groups exist which must be searched, actions for packet classification) are stored in a search result storage device. By doing this it is made possible to search with the bit width of the group unit.

Packet classification search device and method

An automatic accurate alignment system for positioning an object to be worked which has a certain pattern on its surface at a required position. The system performs primary positioning of the object to be worked on the basis of low magnification pattern matching with respect to at least a part of the image of the object magnified at a relatively low magnification. Thereafter, the system performs secondary positioning of the object to be worked on the basis of high magnification pattern matching with respect to at least a part of the image of the object magnified at a relatively high magnification.

Automatic accurate alignment system

An automatic accurate alignment system for positioning at a required position an object to be worked which has a certain pattern on its surface. The system includes a key pattern memory, a pattern matching device and movement control device. The key pattern memory memorizes a first signal indicative of a key pattern existing in a specified area and its position when the object to be worked is positioned at a predetermined position, and memorizes a second signal indicative of the key pattern existing in the specified area and its position when the object to be worked is rotated through 90 degrees from the predetermined the second signal is determined from the first signal. The pattern matching device performs a first pattern matching on the basis of the first signal and a second pattern matching on the basis of the second signal. The movement control device performs a first positioning of the object to be worked on the basis of the first pattern matching, then, rotates the object to be worked through 90 degrees, and thereafter, performs a second positioning of the object to be worked on the basis of the second pattern matching.

An accurate alignment system for positioning at a required position an object to be worked which has on its surface straight-line areas whose image density changes relatively abruptly at their both side edges. The system comprises holding means for holding the object to be worked, moving means for moving the holding means, camera means for taking at least a part of the image of the surface of the object held on the holding means and outputting analog signals showing the densities of x-y matrix arrayed pixels, A/D converter means for converting the analog signals output by the camera means into multi-value digital signals, operation means for performing a mathematical operation on the multi-value digital signals to produce binary digital signals, detecting means for detecting the position of at least one side edge of each straight-line area and thus the position of the straight-line area on the basis of the binary digital signals, and movement control means for actuating the moving means according to the detected position of the straight-line area and thus positioning the object held on the holding means at the required position.

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Tokyo, Japan

Masanori Uga