Hitachi, Ltd.

Yagi Antenna Co., Ltd.

Tetsuhiko Hirata

Mika Mizutani

Tatsuya Yokoyama

Susumu Matsui

Masashi Yano

Minoru Koizumi

Osamu Takada

Matsuaki Terada

Hiroaki Miyata

Koji Wakayama

Kazuho Miki

Norihisa Matsumoto

Hiroaki Nakazawa

Hiroshi Wataya

Shoji Fukuzawa

Emiko Yanagisawa

Kenichi Sakamoto

Toshiro Suzuki

Keisuke Takeuchi

Kenji Kataoka

Yoshiaki Adachi

Ken'ichi Sakamoto

Kazuo Yagyu

Ken Onuki

Motoyoshi Morito

Masaya Hayashi

Sinichi Kouyama

Hiroshi Nakase

Atsushi Teshima

Shigeru Oshima

Takahiko Nishizawa

Masayo Nagano

Hirashi Wataya

An access node run as a packet switching apparatus enables IP connection services for a plurality of access methods; e.g., relatively low-speed IP connection, high-speed IP connection, and mobile network IP connection. By using this apparatus of the present invention, cost can be reduced and upgrading to advanced access networks and access services is easily carried out. Provision of the above access nodes implements upgrade-type network services common for diverse protocols. Each access node retains a pathfinding table to which input port, input tunnel identifier and input session identifier entries in a set are registered per session. When routing a packet, by looking up the set of these entries matching with the packet, the associated output port, output tunnel identifier, and output session identifier are obtained. After processing for the packet, appropriate for one of the plurality of access methods and network services, the node forwards the packet over the routed path.

Packet switching apparatus

There is provided an address translator having the functions to prevent, in the communications via the address translation, transmission of packets having no correct destination and transmission source addresses which will cause troubles in the networks and to urge an administrator take adequate measures for reception of the relevant packets. This address translator stores discriminator to discriminate temporary addresses. Moreover, when the original address is registered as the temporary address at the time of assignment of the temporary address of the receiving side host started when the name solution is performed, assignment is rejected to prevent transmission of packet from the transmitting side host by returning a response for name solution error to the transmitting side host. In addition, when transmission source address before translation and destination address after translation are registered as the temporary address, the received packet is discarded. Moreover, assignment of the temporary address is rejected and the packet is discarded, a message is transmitted to an alarm device or external host to notifying the event to an administrator.

Address translator and method for management of address translation rules

A mobile data communication system capable of shortening the interruption time of communication includes an HA device, advertising routers, base stations, routers, and mobile terminal devices. Each base station advertises an address having '1' set in a different bit of an interface ID of a routing address. When a mobile terminal has received radio waves from a plurality of base stations in the vicinity of a boundary between cells, the mobile terminal combines a plurality of received routing addresses by logical summation and registers a resultant routing address with the HA device. As for a packet delivered from the HA device to the routing address and having '1' in a plurality of bits of the host section, a router resolves the address of the host section into destination addresses each having &#x201c;1&#x201d; in one bit, generates packets each having one of resultant addresses, and transmits the generated packets.

Mobile communication system

A mobile communication system with a packet switching function which enables sharing of radio resources among mobile stations, wherein a mobile station which has generated a request for communication quality assurance periodically sends a packet for requesting preferential use of a radio channel in order to prevent timeout of the state transition timer, timeout of which would cancel radio channel assignment to the mobile station and bring it into a dormant state if a certain period elapses without transmission or reception of a signal, so that it can remain in the active state and hold the radio channel continuously. In addition, when the mobile station requesting communication quality assurance moves from one cell to another or requests radio channel assignment, the base station controller controls the radio base station so that the mobile station can be assigned a radio channel by sending a priority request packet.

Mobile communication systems, mobile stations, base station controllers and packet data service nodes

In a mobile IP network system containing a plurality of radio access networksfor connecting with mobile stationsvia radio links and an IP networkconnected with a plurality of packet nodes for transferring IP packets, each of the radio access networks has at least one base station controllerand at least one radio base stationconnected to the base station controller. Each of the base station controllersin the radio access network is connected to the plurality of packet nodes to each other via a networkand selects one of the plurality of packet nodes in accordance with a state of each mobile station to establish a logical connection to be used in IP packet communication of the mobile station.

Mobile IP network system and connection switching method

A mobile communication system that can obtain mobile station location information repeatedly at short intervals, without depending on whether base stations are synchronous or asynchronous, with lower loads and suppressed use of radio resources. For obtaining location information, a mobile station receives a paging channel periodically sent from a base station (Step ), obtains the contents and the reception timing of this paging channel. Further, if it is necessary to obtain the transmission timing of the paging channel, that transmission timing is obtained (Steps ). The propagation delay of the paging channel or propagation delay differences between a plurality of periodic paging channels are calculated from the transmission timing and the reception timing of the paging channel (Step ). The mobile station location information is calculated from the propagation delay or propagation delay difference, and outputted (Steps ).

Mobile communication system, mobile station, and base station that calculates distance from mobile station

It is designed to connect a duplicated LAN to a network terminal such as a controller having a standard serial or parallel interface, a computer having only one LAN interface, or a computer having only one communication line interface. The network interface apparatus for connecting a network terminal and a duplicated LAN comprises a device for controlling interfaces with the network terminal and the LAN transmission line of each of the duplicated LAN, a buffer, and a sending device to both, and the data from the network terminal is buffered in the buffer, and when the buffered data reaches a fixed amount, the data is sent to both LANs of the duplicated LAN. On the other hand, with respect to the data received from each LAN transmission line of the duplicated LAN, only the data which is judged as earlier arrival data is sent to the network terminal.

Network interface apparatus

A network interface apparatus connected between a LAN adaptor possessed by a computer and a transceiver provided on a network includes a buffer memory for storing data, a first control circuit for communicating with the LAN adaptor, a second control circuit for communicating with the transceiver, and a processor for controlling the first and second control circuits to control the transfer of data between the LAN adaptor and the transceiver. The processor causes the buffer memory to store transmit data transmitted from the LAN adaptor and transmits the stored transmit data in the buffer memory to the transceiver in a transmission time zone which is allotted beforehand. The transmission time zone is determined by the processor on the basis of the reception of a synchronizing packet which is transferred on the network. Receive data received from the transceiver is selected by the processor so that only the selected receive data is sent to the LAN adaptor. A reference for the selection may include a protocol type, a port number on TCP/IP or the like.

Network interface apparatus and data transmission control method thereof

A distributed memory computer system periodically performs memory copy among a plurality of computers by using general-purpose communication control devices and a transmission line of the CSMA/CD type. A master computer periodically generates a synchronizing packet, and transmits data for memory copy and normal data in a time slot immediately after the transmission of the synchronizing packet. Each computer other than the master computer transmits the data for memory copy and the normal data in its own time slot after the elapse of a predetermined time. The respective computers complete their transmissions within predetermined times. Since the time slots are assigned to the respective computers, the number of computers which may compete with each other on a transmission line can be restricted and each computer can be assured a periodic opportunity to transmit data.

Method and system for sequentially broadcasting data according to

Communication control equipment for connecting a computer system to a network and supporting the computer system to set a plurality of connections on the network and perform parallel communication between computers. The communication control equipment includes an interface circuit for the computer system, a microprocessor for performing communication control processing, a local memory for storing programs and work data, a buffer memory for temporarily storing transmission and reception data, a DMA transfer unit for performing data transfer between a memory in the computer system and the buffer memory and protocol header transfer between the buffer memory and the local memory, a network controller for controlling transmission and reception of data to the network, and a header retrieval unit for predicting a protocol header of a frame to be next received in correspondence to each of a plurality of connections and retrieving a header corresponding to a protocol header of a received frame transferred by the DMA transfer unit.

System for executing high speed communication protocol processing by

In a communication control equipment for transmitting data in an external predetermined memory to a network, there are provided a buffer memory unit for temporarily holding the data transferred thereto, a data transfer unit for performing a data transfer between the predetermined memory and the buffer memory unit, a unit for executing a protocol processing with regard to data held in the buffer memory unit, a control unit for controlling a transmission of the data processed by the protocol processing to the network, and a unit for producing a transmission start instruction at a start time instant within a range defined from a time instant when 1-packet data transfer from the predetermined memory to the buffer memory unit is commenced until a time instant when this data transfer is completed. The transmission start instruction is produced under a condition that the lower a data transfer speed from the predetermined memory to the buffer memory unit is relative to a transmission speed of the network, the later the start time instant is. A unit is also provided for causing the control unit to commence the transmission of the data processed by the protocol processing to the network at a later time instant during the time instant when the transmission start instruction is produced and the time instant when the protocol processing is terminated.

Communication control method and apparatus for performing high speed

An arithmetic-logic unit ALU having three data input ports A, B and C, a modulo adder/subtracter for executing an arithmetic-logic operation of (A.+-.B) mod (C+1), a comparator for determining whether the input data A, B and C satisfy at least one of the relationship of A.ltoreq.B.ltoreq., A.ltoreq.B&lt;C, A&lt;B.ltoreq.C and A&lt;B&lt;C from a modulo operation viewpoint, and outputting a comparison judgment signal, a two-input ALU for executing an arithmetic-logic operation of two data, and one data output port for outputting operation results.

Arithmetic-logic unit with modulo addition/substraction function and

A communication control equipment connected between a computer and a network so as to perform protocol processing at a high speed, has a buffer memory connected between a computer interface circuit and a network interface circuit through a first path for data transfer, so as to temporarily store communication data, and a protocol processor connected between the computer interface circuit and the network interface circuit through a second path for control information transfer. The protocol processor is also connected to the buffer memory through a third path so as to effect protocol processing on the communication data within the buffer memory. The protocol processor includes a plurality of processor units connected in series in the second path so as to respond to control information received from the second path to make access to the buffer memory through the third path and to execute a first category of protocol processing necessary in normal data transfer on the communication data stored in the buffer memory. If protocol processing other than the first category of protocol processing on the communication data is necessary, the processor units supply the control information to the third path. The protocol processing also includes a second processor which operates as a backend processor for the processor units and which is connected to the third path so as to respond to the control information received from the third path to execute protocol processing other than the first category of protocol processing on the communication data stored in the buffer memory.

Protocol processing apparatus for use in interfacing network connected

A base-band and broad-band coexisting communication system comprises a transmission path, a plurality of first data terminal units outputting data to be transmitted in the form of pulse signals (base band signals), a plurality of second data terminal units for outputting data to be transmitted in the form of modulated signals (broad band signals) each having a center frequency within a predetermined frequency range, and a plurality of low-pass filters, each connected to each of the first data transmission units, for cutting off high frequency components of the base band signal outputted by the first data terminal device at a predetermined cut-off frequency which does not overlap with the broad band signals.

Growing community of inventors

Yokohama, Japan

Tetsuhiko Hirata