Hitachi, Ltd.

Other

Hitachi Computer Engineering Co., Ltd.

Shigeki Morimoto

Hidehiro Fukushima

Masato Tsukakoshi

Masashi Fukuda

Yoshihito Sako

Tohru Setoyama

Hiroshi Sekino

Nagayuki Hirota

Takunori Yoneno

Kenichi Wada

Toshihiko Murakami

Toshiaki Koyama

Norihide Noyama

Shinya Ichinohe

Shinsuke Suzuki

Toshihiko Nakauchi

Seiichi Ozaki

Norikazu Endo

Hirpyuki Sakoda

Hideyuki Matsuo

Packets of mobile communication protocol which a mobile terminal sends and receives are monitored and when it is detected that a mobile terminal to which a multicast data packet is transferred moved to another network, a multicast gateway apparatus connected to the moving destination network makes a group attend request and transfers the multicast data packet to the moved mobile terminal.

Method, apparatus and system for distributing multicast data

A multicast communication device receives data packets multicast for receiving terminals which terminals do not support multicast communication and that are requesting multicast data packets. The multicast communication device then forwards the data packets to the receiving terminals. Communication from the receiving terminal accessing the sending terminal sending data packets to obtain information is monitored. Based on the access contents, a join group request is issued for the group address used by the multicast delivery. The multicast communication device stores service information such as the address of the sending terminal and the destination address of data packets sent by the sending terminal. If the service to be accessed by the receiving terminal is present, multicast delivery of data packets is requested. The multicast communication device forwards received multicast data packets to the receiving terminal.

Device and system for multicast communication

A packet switching is performed according to a routing information for relaying particular packets which is produced by the route computation based on the information of a received packet and the kept parts-of-routing-information useful as a basis for the route computation. At this time, the route through which the packet is relayed is determined on the basis of the kept parts-of-routing-information before the route computation. Then, the received packet is relayed according to the determined route. Next, a new routing information is produced by the route computation based on the information of the received packet and the parts-of-routing-information. Thereafter, the succeeding packets of the same route are relayed on the basis of the new routing information.

Packet switching method and apparatus thereof

A highly-expandable router configuration technology which flexibly meets the need to increase lines as a network grows. A network information sharing unit is provided in a route calculation unit of each router in a clustered router. The network information sharing unit receives an update notification of network information collected by routing protocol units and sends this update information to all other routers in the clustered router as a network information notification packet. The network information sharing units in the receiving router notifies the routing protocol units of the contents of the received updated information. The routing protocol unit updates the network information thereof based on the notified contents, thereby allowing the network information obtained from all routers outside the clustered router to be shared and the clustered router to be recognized externally as a single router.

Method for sharing network information and a router apparatus

A router device is provided with a plurality of router node devices interconnected via internal transmission lines, in which each of the plurality of router node devices comprises a unit for connecting to a plurality of networks; a routing table describing paths via which packets are forwarded; a forwarding unit for forwarding a packet between one network and another, and for forwarding the packet between the network connected to the router node device and the network connected to some other router node device of the router device via some other router node device, according to the routing table; a routing information collection unit for collecting routing information from each router device connected to the network, not via other router node devices, to the router node device to create a routing table in each router device, the routing information being information to be exchanged among router devices, a distribution unit for distributing the collected routing information to other router node devices via the internal transmission lines; and a routing table generation unit for generating the routing table based on the collected routing information and the routing information distributed from the other router node devices.

Scalable cluster-type router device and configuring method thereof

A multiplex router device, having a multiplex configuration, is instrumental in reducing internal and external traffic flows for a routing protocol process that occurs at a time of system switchover. A data base integration module, in a route calculation unit in the active mode, stores network link-state information collected by a routing protocol packet transmission-reception module in a link-state data base, and at the same time sends the information to a route calculation unit, but does not send routing protocol information collected. In the route calculation unit in the standby mode, a data base integration module that received the network link-state information stores its contents into its own link-state data base. When a failure occurs in the route calculation unit in the active mode, the route calculation unit performs the routing protocol process by using the stored link-state data base.

System and method for using active and standby routers wherein both routers have the same ID even before a failure occurs

In an internetwork apparatus for interconnecting a plurality of networks having a route calculating module for calculating routes and a management module for managing a whole operation of the internetwork apparatus, the management module substitutes for route calculation in place of the route calculating module, when a fault occurs in the route calculating module, and packets are repeated in accordance with route calculation results made by the management module.

Internetwork route calculation execution method and apparatus

Multiplex router device comprising a function for controlling a traffic

A multiprocessor bridge construction allows ports that are operable under a spanning tree protocol to coexist with ports that are inoperable under the spanning tree protocol, thus making it possible to improve the frame-repeating capability of the bridge, to equip the bridge with a large number of ports, and to divide the spanning tree topology into a plurality of portions to be managed.

Multiprocessor bridge having storage for spanning tree operation mode

A method is provided for controlling bus-using rights in a multi-bus system which has a plurality of buses and a plurality of units connected to each of the buses. A unit connected to one bus is accessible by another unit connected to another bus. When a first unit accesses either a second unit on the one bus or a third unit on another bus, two requests for use of the one and another buses are issued substantially at the same time, thereby reducing the time taken for acquiring a bus-using right of the another bus. As soon as it is found that access is directed to the second unit on the one bus, the request for using the another bus is canceled, thus reducing a bus occupation rate for the another bus.

Bus system wherein a bus-using request signal is issued in advance of a

A level machine information system is provided with an instruction register for storing an address of an instruction read out from an instruction memory, an instruction decoder for producing control signals complying with the instruction read out, a calculator for producing a new address of an instruction to be executed next on the basis of the address outputted from the instruction register, an instruction length code supplied from the decoder as the control signals, a plurality of first registers for saying the address outputted from the instruction register, a plurality of second registers for saving the new address, a controller and a selector for supplying the instruction register with the new address, the saved new address and fixed addresses each indicating the head of interruption programs in the instruction memory. The first and second registers correspond to all but the highest interruption priority level. Upon an acknowledged interruption request, the controller controls the first and second registers and selector to save the new address of the calculator and the old address of the instruction register in one of the first and second registers corresponding to the priority levels of an interrupted process, respectively. One of the fixed addresses corresponding to a process to be executed for the interruption request is transferred in the instruction register. If necessary, the contents of the first and second registers are referenced by the process to detect the reasons for the interruption.

Information processing system with instruction address saving function

In communications control unit for sequentially scanning a plurality of line sets to which full-duplex lines are connected, for reading out line control word provided in correspondence to the line from a memory when a data transmission/reception request exists in the line set, and for executing the data transmitting and receiving operations with the relevant line set, one line control word including both of transmission control information and reception control information is read out in the time slot assigned to one full-duplex line, and the data transmitting and receiving operations are simultaneously executed.

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Atsugi, Japan

Shigeki Morimoto