Hitachi, Ltd.

Other

Hajime Abe

Akihiko Takase

Atsushi Takai

Noboru Endo

Kazuho Miki

Yoshito Sakurai

Takahiko Kozaki

Kota Miyoshi

Yoshinao Kiuchi

Takaaki Higashi

Upon initialization, a VPC is set up between edge nodes. A control processor of each node creates an IP address/VPC mapping table using IP routing information and an address mapping table mapping correspondence between IP addresses and ATM addresses and supplied by a network management system. A gateway assigns a VCC to each packet input to the network. A sending-side edge node inputs the packet to the VPC corresponding to its destination by referring to the IP address/VPC mapping table. A transit node performs packet switching over VP. A receiving-side edge node transfers each packet to the gateway corresponding to its destination. If a series of packets meet a predetermined condition in a given edge node, its control processor sends VCC information to input interfaces of the edge node so that the packets are switched by an ATM switch in the edge node without intervention of the control processor.

Packet switching system, packet switching network and packet switching method

This invention provides a network management equipment and a packet switching equipment which eliminate a connection setup delay time, reduce a delay and a delay variation involved in data transfer, and effectively perform connectionless data flow processing in a large data network. The network is divided into a connection-oriented core network and a plurality of connectionless access networks connected to the core network where a plurality of connections (called permanent virtual route (PVR)) are set up among a plurality of edge nodes. The network management equipment selects one route from a plurality of PVRs for connectionless data flow received from one of the access networks and transfers data along the PVR.

Packet switching network, packet switching equipment and network management equipment

To detect network faults or congestion of traffic at an interface of a gateway system for connecting an IP network and a telephone network on the side of the IP network and to allow the IP network to control alternative routing at the telephone network, network faults and congestion of traffic on the side of the IP network are monitored by the gateway system having an interface function between the telephone network and the IP network. When a network fault or congestion of traffic is detected, the gateway system notifies the telephone network upstream thereof of the disabled line and instructs the same to perform alternative routing, which makes it possible to prevent the occurrence of a situation in which the quality of communication at the interface between the telephone network and IP network can not be maintained.

Gateway system having controller and signal processor for interconnecting IP network and telephone network and method for controlling alternative routing at the time of fault of gateway system

Packet switching network, packet switching equipment, and network management equipment

The cell output control apparatus includes a cell time slot allotment circuit for allotting, cells to be transmitted, to cell time slots with the cell transmission intervals changed, a first holder circuit for holding the value of ACR (Allowed Cell Rate), a first calculator circuit for calculating the ratio, LCR (Line Cell Rate)/ACR, a quantizer circuit for quantizing the ratio, LCR/ACR and controlling the allotment of cell time slots on the basis of the quantization error produced by the quantization, a counter for counting the values of cell time slots, a second calculator circuit for calculating the cell time slots for cells, and a second holder circuit for holding the calculated results, whereby it is possible to absorb the quantization error produced when the ratio, LCR/ACR is quantized into an integral value.

Cell output control apparatus and method

Packet switching network, packet switching equipment, and network

An optical transmission device which is used for a short range optical data link or an optical communication system for subscribers and more particularly requires no automatic optical power control minimizes the turn-on delay time of a laser diode and allows unformatted optical signal transmission by fixed level decision receiving system. By applying a fixed-bias electric current which is not more than the electric threshold current value of the laser diode to the laser diode, the turn-on delay time of the laser diode can be minimized, and the extinction level can be lowered by it, and the fixed level decision receiving system can be used, and the optical receiver circuit can be simplified more.

Driving circuit of laser diode and optical transmission device

A parallel optical transmission device is disclosed, which comprises a transmitter section having one or a plurality of transmitter modules converting one or a plurality of input electric signals into optical signals; a section consisting of bundles of optical waveguides 20i, j transmitting the optical signals; and a receiver section having one or a plurality of receiver modules reproducing the electric signals from the optical signals thus transmitted to output them; wherein all propagation delay times from the input electric signals to the output electric signals are set in predetermined regions.

Optical parallel transmission device

An optical transmission time measuring device for an optical transmission path includes an optical bidirectional coupler having at least two input ports and at least two output ports. A pulse light source is connected to one of the input ports of the coupler and photodetector is connected to another one of the input ports. A timing control unit is used to time the pulse light source and the photodetector. A first optical connector is connected to one of the output ports for connecting a reference optical waveguide thereto and a second optical connector is connected to another one of the output ports for connecting a measured optical waveguide thereto.

Growing community of inventors

Yokohama, Japan

Hajime Abe